Dissertation on “ANATOMICAL ANALYSIS OF ORIGIN, BRANCHING PATTERN AND VARIATIONS OF SUBCLAVIAN IN HUMAN CADAVERS’’

Submitted to

THE TAMILNADU Dr. M. G. R. MEDICAL UNIVERSITY Chennai – 600 032

In partial fulfillment of the requirement for the award of degree of

DOCTOR OF MEDICINE IN ANATOMY BRANCH - XXIII

Submitted by

Register Number: 201733351

KARPAGA VINAYAGA INSTITUTE OF MEDICAL SCIENCES AND RESEARCH CENTRE MADHURANTHAGAM TAMILNADU MAY 2020

1 CERTIFICATION

This is to certify that “ANATOMICAL ANALYSIS OF ORIGIN,

BRANCHING PATTEREN AND VARIATIONS of SUBCLAVIAN

ARTERIES IN HUMAN CADAVERS’’ is a bonafide work of

Dr. T.N.Pavazhakkurinji, in partial fulfillment of the requirements for the M.D

Anatomy (Branch-XXIII) examination of The Tamilnadu Dr. M.G.R Medical

University to be held on May 2020.

Dr. T.L.Anbumani., M.D., M.S Dr. Sufala Sunil Vishwas Rao., MD Vice Principal and Principal, Head of the Department, Karpaga Vinayaga Institute of Medical Department of Anatomy, Medical Sciences and Research Centre Karpaga Vinayaga Institute of Medical Madhuranthagam. Sciences and Research Centre Madhuranthagam.

2 CERTIFICATION

This is to certify that “ANATOMICAL ANALYSIS OF ORIGIN,

BRANCHING PATTEREN AND VARIATIONS of SUBCLAVIAN

ARTERIES IN HUMAN CADAVERS’’ is a bonafide work of

Dr.T.N.Pavazhakkurinji in partial fulfillment of the requirements for the M.D

Anatomy (Branch-XXIII) examination of The Tamilnadu Dr. M.G.R Medical

University to be held on May 2020.

Dr. T.L.Anbumani, M.D., M.S Head of the Department, Professor and Guide, Department of Anatomy, Karpaga Vinayaga Institute of Medical Sciences and Research Centre. Madhuranthagam.

3 DECLARATION

I, Dr.T.N.Pavazhakkurinji hereby declare that this dissertation

“ANATOMICAL ANALYSIS OF ORIGIN, BRANCHING PATTEREN

AND VARIATIONS OF SUBCLAVIAN ARTERIES IN HUMAN

CADAVERS’’ is a presentation of my own work and that it has not been submitted anywhere for any award. Wherever contributions of others are involved, every effort is made to indicate this clearly, with due reference to literature and discussions. This work was done under the guidance of

Professor Dr. T.L.Anbumani, MD., M.S., at Karpaga Vinayaga Institute of

Medical Sciences and Research Centre, Madhuranthagam.

Candidate’s Name: Dr. T.N.Pavazhakkurinji

Candidate’s signature:

Date: In the capacity as guide for the candidate’s dissertation work, I certify that the above statements are true to the best of my knowledge.

Dr.T.L.Anbumani. MD., M.S., Head of Department, Professor and Guide, Department of Anatomy, Karpaga Vinayaga Institute of Medical Sciences and Research Centre, Madhuranthagam

4 ACKNOWLEDGEMENT

First of all I would like to thank our beloved Professor T.L.Anbumani M.D, M.S., Vice principal and Head of the department for guiding and supporting me over the years. You have set an example of excellence as a Mentor, Instructor and Role model.

I would like to express my sincere and heartfelt Gratitude to respected Managing director Prof.Dr.R.Annamalai M.S. and Dr.Sufala Sunil Vishwas Rao M.D. for permitting and extending their valuable support in conducting the study.

I would like to thank Dr.A.Thamari selvi M.D. Assistant Professor for all of her guidance throughout this process; her discussions, ideas and feedback have been absolutely invaluable.

My sincere thanks to all the Faculty Members in the Department of anatomy for their valuable guidance and support during this study.

I would like to thank my Fellow graduate students, Technicians and supporting staffs who contributed to this study. I am very grateful to all of you.

My sincere thanks to my family members and friends for their moral support given in all the time in completing this dissertation.

5 CONTENTS

CHAPTER PAGE TITLE NO. NO. 1. INTRODUCTION 1 2. AIM AND OBJECTIVES 14 3. REVIEW OF LITERATURE 15 4. MATERIAL AND METHODS 43 5. OBSERVATION AND RESULTS 45 6. DISCUSSION 74 7. SUMMARY AND CONCLUSION 90 BIBLIOGRAPHY 95 ANNEXURES 110 a) PLAGIARISM ANALYSIS REPORT 111 b) PLAGIARISM SCREEN SHOT REPORT 112 c) DR.MGR MEDICAL UNIVERSITY 113 PLAGIARISM VERIFIED GUIDE CERTIFICATE d) INSTITUTIONAL ETHICAL COMMITTEE 114 APPROVAL CERTIFICATE e) ABBREVIATIONS 115

6

INDEX FOR TABLES

7 INDEX FOR TABLES

TABLE PAGE TITLE NO. NO. 1. NUMBER OF BRANCHES OF SUBCLAVIAN 45 2. NUMBER OF BRANCHES OF FIRST PART OF 46 3. ORIGIN OF 47 4. LEVEL OF VERTEBRAL ARTERY ENTREING 47 TRANSVERSE FORAMINA 5. ORIGIN OF INTERNAL THORACIC ARTERY 48 6. NUMBER OF BRANCHES OF THYROCERVICAL 52 TRUNK 7. ORIGIN OF 56 8. RELATION OF RECURRENT LARYNGEAL NERVE TO 57 INFERIOR THYROID ARTERY 9. PRESENCE /ABSENCE OF TRANSVERSE CERVICAL 59 ARTERY 10. ORIGIN OF 60 11. BRANCHES OF 64 12. PRESENCE/ABSENCE OF BRANCHES IN THIRD PART 65 OF SUBCLAVIAN ARTERY 13. ORIGIN OF DORSAL SCAPULAR ARTERY 65 14. RELATION OF DORSAL SCPAULAR ARTERY WITH 67 15. COMPARISON OF VERTEBRAL ARTERY ORIGIN 75

8

INDEX FOR CHARTS

FIGURE PAGE TITLE NO. NO 1 PERCENTAGE OF BRANCHES OF SUBCLAVIAN 46 ARETRY 2. PERCENTAGE OF BRANCHES OF THYROCERVICAL 52 TRUNK 3. PERCENTAGE OF RELATION OF RECURRENT 57 LARYNGEAL NERVE WITH INFERIOR THYROID ARTERY. 4. PERCENTAGE OF TRANSVERSE CERVICAL ARTERY 59 PRESENCE AND ABSENCE 5. ORIGIN OF SUPRASCAPULAR ARTERY 61 6. PERCENTAGE OF DORSAL SCAPULAR ARTERY 67 ORIGIN 7. RELATION OF DORSAL SCAPULAR ARTERY WITH 69 BRACHIAL PLEXUS 8. COMPARATIVE CHART OF VERTEBRAL ARTERY 76 ORIGIN 9. COMAPARTIVE CHART OF ORIGIN OF INTERNAL 78 THORACIC ARTERY FROM 10. COMPARATIVE CHART OF THYROCERVICAL 80 TRUNK HAVING TWO BRANCHES 11. COMPARATIVE CHART OF RELATION OF 82 RECURRENT LARYNGEAL NERVE WITH INFERIOR THYROID ARTERY

9 FIGURE PAGE TITLE NO. NO 12. COMPARATIVE CHART ON ORIGIN OF 83 TRANSVERSE CERVICAL ARTERY FROM THYROCERVICAL TRUNK 13. COMPARATIVE CHART FOR VARIOUS ORIGIN OF 85 SUPRASCAPULAR ARTERY 14. COMPARATIVE CHART FOR ABSENCE OF DEEP 86 CERVICAL ARTERY 15. COMPARATIVE CHART OF ORIGIN OF DORSAL 88 SCAPULAR ARTERY 16 MASTER CHART 70-73

10 INDEX FOR FIGURES

FIGURE PAGE TITLE NO. NO 1. ORIGIN OF VERTEBRAL ARTERY FROM ARCH OF 49 2. INTERNAL THORACIC ARTERY ORIGIN FROM 50 THYROCERVICAL TRUNK 3. THYROCERVICAL TRUNK WITH TWO BRANCHES 53 4. THYROCREVICAL TRUNK WITH FIVE BRANCHES 54 5. ABSENCE OF THYROCERVICAL TRUNK 55 6. RECURRENT LARYNGEAL NERVE BETWEEN THE 58 BRANCHES OF INFERIOR THYROID ARTERY 7. SUPRASCAPULAR ARTERY ORIGINATING FROM 62 THIRD PART OF SUBCLAVIAN ARTERY 8. SUPRASCAPULAR ARTERY FROM AXILLARY 63 ARTERY 9. DORSAL SCAPULAR ARTERY FROM CERVICO 66 SCAPULAR TRUNK 10. DORSAL SCAPULAR ARTERY BELOW THE TRUNKS 68 OF BRACHIAL PLEXUS

11 CHAPTER – I

INTRODUCTION

SUBCLAVIAN ARTERY AND ITS BRANCHES

12

INTRODUCTION

The human body itself have countless difference in structure and many of these variations have been documented in anatomical literature. One such structure is subclavian artery and its arterial branches originating from it.

Subclavian artery and its branches reside in compact and complex anatomical space. Subclavian artery’s such location makes it difficult exposure during surgery. Also there is much uncertainty and variability in literature of subclavian artery.

With recent increase in the use of CT, MRI and angiography it has been pointed that accurate understanding of morphology of normal subclavian artery, and its ramifications are essential for accurate diaganosis1. Sternocleidomastoid and muscle are frequently used as musculocutaneous flap in reconstructive surgery. These muscles are supplied by branches of subclavian artery, but the literatures on these arteries are limited2.For these purpose a study is conducted for origin, ramification of subclavian artery.

In the root of the key orienting structure is Scalenus anterior muscle.

It arises from anterior Tubercles of C3-C6 and inserted into scalene tubercle on superior aspect of first rib. The main vascular trunks to head and neck and upper extremity enter root of neck.

13 The aorta is largest artery in human body. The aorta arises from left ventricle of heart to deliver oxygenated blood. It is divided into , arch of aorta, and . The ascending aorta runs superiorly from its origin to the arch of aorta at the level of T4-T5. The arch of aorta is located in superior mediastinum, progressing posterior to posterior mediastinum as descending aorta.

The common branching pattern of aortic arch in human consists of three vessels, Brachiocephalic trunk, left and subclavian artery.

Vascular anomalies occur as a failure in the congenital development of primordial aortic arch3. These aortic vessels are important in providing vascularisation to the head and neck region. Occlusion of these vessels may lead to impairment of neurological functioning.

Origin of Subclavian artery

On right side subclavian artery arise from brachiocephalic trunk behind right sternoclavicular joint. On left side it arises from arch of aorta. Each subclavian artery divided into three parts by scalenus anterior muscle. Scalenus anterior muscle originates from C3 to C6 vertebrae, inserted into scalene tubercle present in first rib positioned anterior to subclavian artery. Scalenus anterior muscle divides the artery into three parts. First part extends from origin to medial border of scalenus anterior. Second part behind the muscle. Third part extends from lateral border of scalenus anterior to outer border of first rib. First part of

14 both side have separate description and relation .C5 –T1 nerve roots of brachial plexus originate from cervical transverse foramina of C5-C7 and T1,anterior primary rami of these roots unite to form upper, middle and lower trunks. Lower trunks is closely associated with Subclavian artery.4

First part:

Right subclavian artery arises from right brachiocephalic trunk. The relation are in front by superficial fascia, platysma, deep fascia, clavicular origin of sternocleido mastoid, sternohyoid, sterno thyroid.Subclavian artery crossed by internal jugular , vagus nerve, subclavian loop of sympathetic trunk. Below and behind the artery is pleura separating it from apex of lung. Right recurrent laryngeal nerve wind around lower part of artery.

Left subclavian artery.:

First part arise from arch of aorta behind left common carotid artery at the level of fourth thoracic Vertebra. It ascends in superior mediastinum to root of neck, arches lateral to medial border of scalenus anterior.

The relations of subclavian artery in front are vagus nerve, cardiac phrenic nerves. It is also covered by sternothyroid, sternohyoid, sternocleido mastoid in front. Behind it is related with oesophagus, thoracic duct, left recurrent laryngeal nerve, inferior cervical ganglion of sympathetic trunk.

15 Branches of First part: Vertebral artery:

Vertebral artery is the first branch of subclavian artery. Following its origin it runs cranially in transverse foramina of all cervical vertebrae except seventh vertebra and enters cranial cavity through foramen magnum5 and forms basilar artery with its contralateral vertebral artery. Vertebral artery is of its great importance because of its contribution to posterior brain circulation through

Vertebro-basilar system. Various anomalous origin of vertebral artery from Arch of aorta and common carotid artery were reported in literature.

Internal thoracic artery:

The internal thoracic artery arises on anteroinferior aspect of subclavian artery. It passes downwards and medially infront of pleura. The artery enters behind sternoclavicular-joint, it runs caudally behind ribs giving anterior intercostal branches.

Thyrocervical trunk:

The branches of thyro cervical trunk are inferior thyroid artery, suprascapular artery and superficial cervical artery. Normally it arises from anterosuperior side of subclavian artery, proximal to medial border of scalenus anterior muscle.

16 1. Inferior thyroid artery:

It ascends in front of medial border of scalenus anterior and arches medially at the level of C7 vertebra. On reaching lower pole of thyroid gland, the artery divides into ascending and descending branches. The ascending branch anastomose with and supply parathyroid glands. Thyroid gland is highly vascular gland.it receives rich blood supply through superior and inferior thyroid artery. To keep morbidity minimum during thyroid surgery, surgeons should have exact knowledge of topographic anatomy and its variations.

2. Superficial cervical artery:

It passes laterally and upward in front of , scalenus anterior and appears in posterior triangle, in front of trunks of brachial plexus and levator scapulae. The artery descends beneath trapezius and anastomoses with superficial division of descending branch of .

3. Suprascapular artery:

The artery runs behind the , subclavius, and inferior belly of omohyoid and runs above Suprascapular ligament. On reaching dorsal surface of , it forms scapular plexus by anastomosing with circumflex and dorsal scapular arteries.

17 In about one third, dorsal scapular and superficial cervical take a common origin from Thyrocervical trunk in the name of Transverse cervical artery.

Second part:

Second part of subclavian artery lies behind scalenus anterior. On Right side phrenic nerve separated from Second part by scalenus anterior, while on left side phrenic nerve crosses first part of artery close to medial border of scalenus anterior muscle. Behind the vessels it is related to pleura and scalenus medius.

From the second part on the right side, arises costo cervical trunk (CCT)

.The branches of costocervical trunk are highest intercostal artery, and . On the left side costo cervical trunk arises from first part. These arteries supply deep neck muscles and first two intercostal space. It has also been reported that accessory ascending cervical artery also arise from subclavian artery in the absence of CCT .6

Third part:

It extends from lateral border of scalenus anterior to outer border of first rib, then it continuous as . It is covered in front by skin, superficial fascia, platysma, . Behind the third part of subclavian artery is related to nerve to subclavius. Branches of third part of subclavian artery are,

Dorsal scapular artery which passes backwards to supply levator scapulae, rhomboids and contribute to anastomoses of .

18 The subclavian artery and its branches have variations in origin, course and its branches. The variations have greater importance in blood vessels surgery and angiographic investigations. The branches of this artery are important in conducting blood to spinal cord, thyroid gland, thoracic wall.

Internal thoracic artery is routinely used in coronary artery bypass grafting7.So the study on variations of these vessels will be helpful.

Developmental anatomy:

During the development of pharyngeal arches in fourth and fifth weeks, each arch will have its own Cranial nerve and artery. These arteries are aortic arches from aortic sac. These aortic arches embedded in mesenchyme of pharyngeal arches.

The left and right subclavian artery have different embryological origins.

Blood vessels develop from mesoderm.

Pharyngeal artery and their fate:

First artery to appear in embryo is right and left primitive aorta. They are continuous with two Endocardial heart tubes. Each primitive aorta consists of portion lying ventral to foregut called Ventral aorta and portion lying dorsal to gut is dorsal aorta. After fusion of two endocardial tubes two ventral aorta fuse to form aortic sac. Unfused part remains as right and left horns. Now successive arterial arches appear, which is being connected ventrally to right and left horn of

19 aortic Sac and dorsally to dorsal aorta. Greater part of first and second aortic arch disappears. Fifth arch Artery also disappears. Aortic sac is now connected with

3rd, 4th and 6th arches. 3rd and 4th opens into ventral part, 6th arch opens into dorsal aorta.

Spiral septum formed in truncus arteriosus extends into aortic sac and fuse with posterior wall in such a way that blood from pulmonary trunk passes only to sixth arch artery. From ascending aorta blood passes to 3rd and 4th arch arteries.

Several changes now take part in aortic arches to produce adult pattern.

1) Two dorsal aorta grow cranially beyond first arch artery

2) Portion of dorsal aorta which lies between attachment of 3rd and 4th arch

artery disappears on both sides.

3) Each 6th artery gives off artery to lung bud. on right side portion of sixth

arch artery between this bud and dorsal aorta disappears. On left side this

20 part remains patent and forms ductus arteriosus, carrying most of blood

from right ventricle to dorsal aorta.

Dorsal aorta gives off a series of lateral intersegmental branches to body wall.7th cervical Intersegmental lies near the attachment of fourth aortic arch

Ascending aorta and pulmonary trunk is formed from Truncus arteriosus. Arch of aorta formed from ventral part of aortic sac and left 4th arch artery.

Descending aorta from left dorsal aorta below the attachment of 4th arch artery.

Brachiocephalic artery is formed from right horn of aortic sac. Right subclavian artery is formed from proximal part from right fourth arch artery .

Remaining part of right subclavian artery is from seventh intersegmental artery.

Common variant of aortic arch anomaly cause arteria lusoria8.

Left subclavian artery arises from 7 the intersegmental artery. It is known that genetic mutation (22q11 deletion syndrome) can influence development of aortic arch through TBX1 and fibroblast growth factor genes9.

Abnormal origin of right subclavian artery:

Sometimes right subclavian artery arises from descending aorta and courses upwards to right, behind Trachea and oesophagus which causes difficulty in swallowing. This condition is called as Dysphagia Lusoria.

21 This anomaly is caused by degeneration of right fourth aortic arch, right seventh intersegmental artery and dorsal aorta caudal to it is continued as right subclavian artery.

Development of vertebral artery:

Primitive dorsal aorta gives three groups of branches.

1) Ventral splanchnic arteries supplying gut

2) Lateral or intermediate splanchnic arteries supplying structures

developing from intermediate Mesoderm.

3) Dorsolateral or somatic intersegmental arteries, which divides into

dorsal and ventral division.

Dorsal division supply muscles of back gives spinal branch, medially to supply spinal cord. In neck dorsal branch are connected by anastomoses.

Precostal anastomoses occurs in front of neck of ribs, Post costal anstomoses between costal elements and transverse process. Post Transverse anastomoses behind transverse process.

Precostal anastomoses forms thyrocervical trunk, ascending cervical artery, superior intercostal Artery.

Post costal anastomoses forms greater part of vertebral artery.

Post transverse anastomoses forms deep cervical artery.

22 First part of artery is i.e. from its origin to point of entry into foramen transversorium of C6 is formed by dorsal division of seventh cervical intersegmental artery.

Second part lying in transversorium is formed from post costal anastomoses between C1 to C6 intersegmental arteries.

Third part running transversely on arch of atlas is derived from spinal division of dorsal branch of Somatic intersegmental artery.

The ventral division of somatic intersegmental arteries are interconnected by anastomoses and forms internal thoracic artery on ventral aspect near midline

Abnormal origin of vertebral artery:

Origin of vertebral artery from aortic arch is because of degeneration of normal origin from seventh Intersegmental artery with persistence of higher intersegmental artery such as sixth10.

Development of internal thoracic artery

Main stem of the internal thoracic artery is formed by ventral divisions of the seventh cervical intersegmental artery. Vertical part of the artery is derived from the ventral anastomoses between divisions of thoracic Intersegmental arteries.

23 Applied Anatomy

Subclavian Steal Syndrome:

It is a condition in which the subclavian artery proximal to the origin of the vertebral artery is affected with stenosis or blockage. The blockage causes the reverse blood flow in the vertebral artery which is termed the "steal", because it steals blood from the cerebral circulation. Blood is drawn from the contralateral vertebral, basilar or carotid artery regions into the low-pressure ipsilateral upper limb vessels. The term subclavian steal syndrome is applied when reversed vertebral artery flow causes cerebral ischemia with associated symptoms of vertebrobasilar hypo perfusion and/or symptoms of brainstem or arm ischemia. This syndrome exists as an important consideration in the differential diagnosis of cerebral and brachial ischemia.

Cervical rib

At the exit from neck, the brachial plexus and subclavian artery pass through a narrow triangle bounded by two scalene muscle and first rib. Cervical rib is an additional rib which arises from 7th cervical vertebra, which is usually attached to 1st rib close to insertion of scalenus anterior. This cervical rib may compress the subclavian artery, this compression may result in aneurysm. This is a potential source of emboli to hand which may cause gangrene to hands.

24 Coronary artery bypass surgery:

Internal thoracic artery is commonly used as a conduit to bypass coronary artery stenosis and have shown long term patency and survival rate compared to saphenous vein grafts.

Aberrant retro oesophageal subclavian artery:

In this condition right subclavian artery arise as a separate branch from arch of aorta, instead of brachiocephalic artery. The subclavian artery arises from descending aorta and courses upwards behind trachea and oesophagus. This causes compression of oesophagus which causes difficulty in swallowing. This condition is called as dysphagia lusoria.

25 CHAPTER – II AIMS & OBJECTIVES

26

AIMS AND OBJECTIVES

To study the origin course and branching pattern of subclavian artery

Parameters chosen for Observation in this study are

1 Origin of Subclavian artery 2 No.of branches of Subclavian artery 3 No. of branches in first part 4 Origin of Vertebral artery 5 Length of Prevertebral segment of Vertebral artery 6 Origin of Internal thoracic artery 7 Origin and branches of Thyrocervical trunk 8 Site of origin of Inferior thyroid artery 9 Relation of Inferior thyroid artery to recurrent laryngeal nerve 10 Origin of Transverse cervical artery 11 Origin of Suprascapular artery 12 Branches of second part of Subclavian artery 13 Branches of Costocervical trunk 14 Branches of third part of subclavian artery. 15 Origin of Dorsal scapular artery 16 Relation of Dorsal scapular artery to brachial plexus

27 CHAPTER - III

REVIEW OF

LITER ATURE

28

REVIEW OF LITERATURE

1. Origin of subclavian artery and length:

In the study done by Poonam etal11 on variations of subclavian artery, right subclavian artery arises from aortic arch instead of brachiocephalic trunk in one of limbs out of 59 limbs.

In this study, left subclavian artery originated from usual level between

T3 and T4.

Normal level of origin right subclavian artery behind sternoclavicular joint was seen in 58 limbs, in one limb originated below sterno clavicular joint, another one above and lateral to sternoclavicular joint.

In this study length of right subclavian artery was measured which is 7.8 cm and length of left subclavian artery is 9.5cm. The anomalous right subclavian artery arising directly from aorta was abnormally long-length12.3 cm.

Subclavian artery is different on right and left side. the right side subclavian arises from right brachiocephalic trunk behind right sterno clavicular joint. Left side subclavian arises from aortic arch in superior mediastinum and passes into root of neck.

In a report by Anthony Ocaya12 Stated that retro oesophageal right subclavian artery was seen originating as last branch from postero lateral aspect

29 of thoracic aorta at the level of T4. The vessel passed anterolaterally to right, posterior to oesophagus and trachea to reach right axilla. Right vertebral and internal thoracic arteries arise normally from this vessel.

In the study done by Valeria Paula et al13 found that during routine dissections an unusual origin of carotid artery and subclavian artery was observed. Right subclavian artery was found as last branch of arch of aorta. This artery is known as retroesophageal subclavian artery.

2. Subclavian artery branching pattern

According to Henry Gray14 branching pattern of subclavian artery on the first part are three branches namely vertebral artery, Internal thoracic artery, thyrocervical trunk, on the left side four branches additionally costocervical trunk. From the second part on the right side costocervical trunk arises. Left side of second part have no branches. third part on the right and left have dorsal scapular artery.

In the study done by Toyaharu et al15 classified the subclavian ramification into three types.

In Type 1,(82.6%) with thyrocervical trunk formed by ascending cervical,

Transverse cervical Artery and inferior thyroid artery and suprascapular artery, other branches vertebral artery and internal thoracic artery separately from first part of subclavian artery, Costocervical Trunk from second part.

30 In Type 2, the transverse cervical artery with internal thoracic artery forms a common trunk.

In Type 3, the ascending cervical and inferior thyroid artery as a separate trunk.

3. Variations of subclavian arterial branching pattern:

In this study done by Juwan Ryu16 found that normal branching pattern which is in Medical curriculum is only 12.9% rest all are different. The order of arteries arranged is Vertebral artery 1st in 80.2%, with Internal thoracic artery arising 2nd (41.3%), Thyro cervical trunk as third branch(47.3%), costo cervical trunk as fourth branch in (56.9%).

In the study done by Janani Maheshwari vyas et al17 thirty-two arteries were classified based on Ramification of thyrocervical trunk into three types. In type 1: typical branching of thyrocervical trunk in 20 arteries. Type 2:Ascending cervical artery arises from TCT as one of the branch in 11 arteries .In Type

3,TCT is absent and its branches directly arise from first segment of subclavian in one artery.

4. Variations of parts of subclavian artery:

In a case study by Perumal et al18 there was a rare variations of Right scalenus anterior muscle having two heads of origin, one head from C3,

C4,another head from C5, C6, inserted separately into scalene tubercle. In this

31 article they also find a common trunk for internal thoracic artery and thyrocervical trunk. This common trunk runs between two heads of scalenus anterior. Left side branches were normal.

In the case study done by Uemura M 19found that bilateral subclavian artery passing in front of scalenus anterior muscle in cadaver. Bilaterally scalenus anterior originated from anterior tubercle of transverse process of fifth and sixth cervical vertebra and inserted in scalene tubercle of first rib.

In the study by Toyaharu Takafugi15 in Japanese populations 142/144 subclavian artery was posterior to scalenus anterior, in one case on left side subclavian artery transfixed to scalenus anterior. In another case on left side subclavian artery is anterior to scalenus muscle.

5. Vertebral artery

In the study by Neelesh Kanasker20 origin of vertebral artery was studied in 30 formalin fixed cadavers, origin of left vertebral artery from arch of aorta between left common carotid artery and left subclavian artery in 5 specimens. In one specimen it is seen as a branch near root of subclavian artery.

In the study by Luctly shields 21 observed in aortic arch there are three branches, if the branch is more vertebral artery is suspected.

In the study bilateral variations of vertebral artery Hadimani et al22 was seen which is not common.

32 Left vertebral artery arise between left common carotid artery and left subclavian artery. Prevertebral segment was measured which is 89 mm.

On Right side -right brachiocephalic trunk terminates into three divisions namely, right common carotid artery, vertebral artery and right subclavian artery.

Length of prevertebral segment was 57mm.

In the study done by Raveendranath Veeramani23 origin of vertebral artery from first part of subclavian artery in 96% (64 of 67). Most common site of origin of vertebral artery was from cranial aspect of subclavian artery. Much less common site of origin of vertebral artery was from dorsal aspect of subclavian artery.

In two cases from arch of aorta .vertebral artery origin was between left common carotid artery and left subclavian artery and in another it was from thyrocervical trunk on right-side.

Three arteries had stenotic segment within 1cm origin., while one artery had a dilatation close to origin.

In the study done by Dr. Manjappa24 on Anatomical variations in branching pattern of aortic arch, he observed 4 types of variations in aortic arch branches. In the second type —in 3 specimens out of 100 he observed aortic arch branches to be four ,namely brachiocephalic trunk, left common carotid artery, left vertebral artery, left subclavian artery.

33 In another type 2/100 aortic arch gives three branches.one common stem for brachiocephalic and left common carotid artery, left vertebral artery and left subclavian artery. An average distance between mid-vertebral line and point of origin of left subclavian artery is 25.04mm. Average distance of midvertebral line and point of origin of left vertebral artery is 24.98mm.

In the study by Durai pandian et al25 branching pattern aortic arch was studied. In 19 cases /30 cases normal branching pattern. In 10/30 left common carotid in common trunk with brachiocephalic trunk. In one cadaver, left vertebral artery arising directly from aorta.

In anatomical study of aortic arch variations by Alsaif et al26 mentioned that Aortic arch variations mean, number of branches of aortic arches. In this study distance from origin to mid vertebral line, were measured. In 27/36 specimens it had three branches, brachicephalic trunk, subclavian artery left common carotid artery. In 2 cadavers aortic arch had 4 branches, the fourth branch is left vertebral artery origin. In 6 specimens, only 2 great branches were seen, common trunk which incorporates brachiocephalic trunk and left common carotid artery. In one cadaver left vertebral artery arose with left subclavian artery from a common trunk.

In the study done by Toyaharu et al15 found that vertebral artery branch independently from first part of subclavian artery in 129/144 arteries, vertebral

34 artery branching directly from arch of aorta in 5 cases. He also found vertebral artery in common trunk with inferior thyroid artery in 2 cases.

In the study done by Yamaki et al27 examined origin of right and left vertebral arteries in their entrance point to cervical transverse foramen. It was dissected in 515 Japanese Cadavers.5.8% (30 cadavers) of vertebral arteries arise from arch of aorta between left common carotid and subclavian artery.

Among 30 arteries 20 arteries entered cervical foramen transversorium at a level higher than C6.

In the study done by Tardieu et al28 they found that vertebral artery from aortic arch ascends more medially prone for iatrogenic injury. They also enter foramen more cranially than the usual c6 vertebra. Spine surgeons approaching anterior aspect of cervical spine should be aware of aortic origin of vertebral artery.

In the study done by Shylaja et al29 found vertebral artery having aortic origin in 2 cadavers out of 15 cadavers on left side. Right side there was no variation, they were arising from subclavian artery.

Nurcan Imre et al30 observed, left vertebral artery originated from aortic arch between origin of left common carotid artery and left subclavian artery.

In the study by Adachi 31 also observed that origin of vertebral artery of aortic origin in 5.4%.

35 In the study by Dasler Anson32 on subclavian arteries the incidence of vertebral artery from subclavian artery is 1-3%.

6. INTERNAL THORACIC ARTERY:

In the study done by Jorge. Henrique Pino etal33 found that the origin of left internal thoracic artery from subclavian artery in 70%,common trunk with other arteries in 30%.Right internal thoracic artery of about 95% arises from subclavian artery;5% of internal thoracic artery in common trunk with other arteries.

In the study by Tanvaa Tansatit34 in Thai populations he did study on variations of branches of subclavian artery found internal thoracic artery from first part in 97%, from third part of subclavian artery in 3%.

In the study done by Nidhi Puri35 found that 15% of internal thoracic artery was in common trunk with other branches of subclavian artery. Phrenic nerve lies in close relation to internal thoracic artery and crossed the artery from lateral to medial side.

In the study done by Delmotra36 on 60 internal thoracic arteries, 55 arteries having origin from first part of Subclavian artery as a separate branch.

Five internal thoracic arteries from common trunk of Thyrocervical trunk.

36 In this study done by Murray etal37 Preoperative imaging of internal thoracic artery prior to breast reconstruction was done. Internal thoracic artery present in 100%. Duplicate internal thoracic artery is observed in two cases.

In a case report by Babu BP38 found that normally internal thoracic artery arises from inferior aspect of first part of Subclavian artery, but in this case study internal thoracic artery was found to arise from Thyocervical trunk.

In the study done by Toyaharu et al15 found Internal thoracic artery from first part of subclavian artery in 87.5%. In 3.5% it was found to be arising from

Thyrocervical trunk.

Study done by Andreas39 observed that variation on internal thoracic artery will have common impact on surgical results. The internal thoracic artery usually arises from first part of subclavian artery, also from third part with reported incidence of 0.5 to 1.0%.Such a case was reported in this study that is from third part. Then the artery descends posterior to first rib and enters thorax.

In the study done by Alice .A.C.Murray40 found that internal thoracic artery was present in 100%. Duplicate internal thoracic artery is seen in two cases (1%).Position of internal thoracic artery was between two internal thoracic most frequently (71.5%), and lateral to veins less frequently(6%).

Study done by George Parsakewas41 showed that internal thoracic artery from Thyrocervical Trunk (TCT) was detected during routine dissection. Internal

37 thoracic artery from Thyrocervical trunk making its dissection and preparation during CABG difficult.

In the study by Lischka42 reinvestigated the origin of thyrocervical trunk and its branches. He found that internal thoracic artery, a branch of thyrocervical trunk in 10%.

In the study by Nizanowski43 found in his study that 11.1% of internal thoracic arteries were abnormal origin i.e. from thyrocervical trunk or other parts of subclavain artery.

In the study by Umeura44 also found the abnormal origin of internal thoracic artery from thyrocervical trunk.

7. THYROCERVICAL TRUNK:

Humberto45 did the study on variations in patterns of branching of thyrocervical trunk. In 88.47% inferior thyroid artery is constituent of

Thyrocervical trunk, in 11.53% inferior thyroid artery arises directly from

Subclavian artery. Among the 88.47% ascending cervical artery arises from inferior thyroid artery in 7.69%. In 3.8% it is in common trunk with

Suprascapular artery and transverse cervical artery.

In the study done by Lokanayagi et al46 on branching pattern of thyrocervical trunk classified the trunk according to its number of branches.

38 Three branches from Thyrocervical trunk namely inferior thyroid artery, transverse cervical artery, suprascapular artery was found in 56.5%.

Thyrocervical trunk having four branches are inferior thyroid artery,

Transverse cervical artery, suprascapular artery and ascending cervical artery arise directly from Thyrocervical trunk in 2 cadavers both right and left (5%).

Three branches from thyrocervical trunk, inferior thyroid artery, transverse cervical artery, common stem for supra scapular and dorsal scapular is seen in 20/40(50%) on right side. Similar pattern is seen in left side in

3/40(7.5%).Two branches from thyrocervical trunk, internal thoracic artery, and common stem for suprascapular and dorsal scapular artery in 2/40 (5%).

Only one branch, inferior thyroid artery from thyrocervical trunk is seen in 2/40(5%).

In the study done by Janani Maheshwari Vyas et al17 subclavian artery branching was studied in 16 cadavers.32 arteries were classified according to ramification of thyrocervical trunk into three types.

Type one of this study is typical branching pattern of Thyrocervical trunk.20 arteries found of this type out of 32 .In Type 2, ascending cervical artery arising from Thyrocervical trunk is seen in 11 arteries. In Type 3

Thyrocervical trunk is absent, branches directly arising from first segment of subclavian artery, found in one artery

39 In the study by Elissa et al47 reports the classification of Thyrocervical trunk branching pattern from 64 subclavian arteries. In all the cadavers that had a

Thyrocervical trunk it was arising from subclavian artery distal to vertebral artery, medial to scalenus anterior.

The first common pattern observed is branching of suprascapular artery, transverse cervical artery, inferior thyroid artery in 64.1%.

The second common pattern observed was origin of Inferior thyroid artery and suprascapular artery from common trunk , Transverse Cervical artery separately from subclavian artery is seen in 21.9%. Third common pattern was internal thoracic artery from thyrocervical trunk with inferior thyroid artery,

Suprascapular and Transverse cervical artery. Few cadavers didn’t have

Thyrocervical trunk exhibited. Inferior thyroid artery, transverse cervical artery and suprascapular artery arises separately from subclavian artery.

Maria Bartanuszova48 reported a case of bilateral passage of thyrocervical trunk through anterior scalene muscle, bilaterally internal thoracic artery from thyrocervical trunk. The thyrocervical trunk after giving internal thoracic artery it ended by trifurcating into suprascapular artery, transverse cervical and ascending cervical artery.

In a study by Lopez et al49 40 subclavian artery were studied.

Thyrocervical trunk was present in 38/40,4 of which had four branches, 12 has three branches,22 specimen had two branches. In two cases Thyrocervical trunk

40 was absent. Of the infrequent branches subject to variation in thyro cervical trunk, is internal thoracic artery. In this study infundibular dilatation were seen in six specimens.

Infundibular dilatation is an alteration of the development of a vessel defined as a disproportion of diameter of artery, excessively large in relations to the number of branches . Internal thoracic artery from thyrocervical trunk in

38/40, from subclavian artery in 2/40.In this study they found that two branches were more frequent than 3 or more.

PhilManyacka MA Nyemippe50 did work on branching pattern of collateral branches of subclavian artery. In this study common branching pattern was type D – cervical scapular trunk (suprascapular and superficial cervical artery) from thyrocervical trunk in 16 specimens (28%).

Next common type is 11specimens (19%) which had separate origin for superficial Cervical artery, dorsal scapular and suprascapular artery, next common type is C found in 9 specimens (15%) the cervical dorsal trunk( superficial cervical artery and dorsal scapular artery) from subclavian artery.

In the case report by Keko Ogami51 found that right Thyrocervical trunk arising from third part of subclavian artery lateral to scalenus anterior.

In a case report by Hassan Hassami et al52 observed right side absence of thyro cervical trunk. He observed origin of inferior thyroid artery arising directly from subclavian artery. Other two branches which normally originate

41 from Thyrocervical trunk had different origin, superficial cervical and uprascapular artery from antero inferior aspect of first part of subclavian artery.

In the study done by Toyaharu15 most common pattern observed in 45 cases 31.9% is common trunk for inferior thyroid artery, transverse cervical artery, supra scapular artery and ascending cervical artery. Another pattern of high occurrence 18.8% is in that a branching pattern suprascapular artery is absent.

8. INFERIOR THYROID ARTERY

In the study by Roshan et al53 inferior thyroid artery from thyrocervical trunk was found in all the cadavers on left side. Right side inferior thyroid artery from subclavian artery is seen in 2 cadavers. Mean length of inferior thyroid artery was more on left side.

Knowledge of variation of ramification of artery is essential important for surgical and diagnostic procedure in region of neck. Inferior thyroid artery is more variable than superior thyroid artery.

In the study done by Rajamadhava et al54, he found in all the specimens inferior thyroid artery arises from thyroid cervical trunk. It was ascending anteriorly to medial border of scalenus anterior, runs behind carotid sheath to reach inferior pole of thyroid gland. In all the 55 specimens recurrent laryngeal nerve is a branch of vagus at the level of right subclavian artery. It loops subclavian artery and ascends upwards.

42 In right side inferior thyroid artery is anteriorly related to nerve in 40%, posterior to nerve in 55%. inferior thyroid artery divides into branches on either side of nerve in 5%. Left recurrent laryngeal nerve hooks arch of aorta. Inferior thyroid artery related anterior to the nerve in 20%. artery related posterior to the nerve in 70%. divided into branches on either side of nerve in 7.5%. Inferior thyroid artery absent in left side in 2.5%.

The study done by Thilagavathi et al55 has illustrated about relation of inferior thyroid artery to recurrent laryngeal nerve. In the right side Recurrent laryngeal nerve was found in between branches of inferior thyroid artery in 51%.

Recurrent laryngeal nerve was found posterior to inferior thyroid artery in 37%. recurrent laryngeal nerve was found anterior to inferior thyroid artery in 11%.

In the left recurrent laryngeal nerve was found posterior to inferior thyroid artery in 51.4%,Recurrent laryngeal nerve was found in between branches of inferior thyroid artery in 28.6%. Recurrent laryngeal nerve was found anterior to inferior thyroid artery in 20%.

To avoid injury to recurrent laryngeal nerve in during thyroid surgery thorough knowledge of recurrent laryngeal nerve and it relation with inferior thyroid artery is essential. In the study by T.K. Kumari56 study recurrent laryngeal nerve is superficial to artery in 5/50.deep to artery in 45/50.

43 In the study done by Abhijeet Joshi et al57 inferior thyroid artery was found to be anterior to recurrent laryngeal nerve in 88%. inferior thyroid artery posterior to recurrent laryngeal nerve in 12%.

In the case report by Jhanshahi Mehrdad et al58 found that all the branches of subclavian arise from first part ,none of the artery goes to thyroid gland. Infreior thyroid artery is absent in this case study.

In the case report by Elissa47 found that thyrocervical is absent, and the inferior thyroid artery arise directly from subclavian artery.

9. TRANSVERSE CERVICAL ARTERIES

Ten cadavers were studied by Mary Hurley59 for source and length of transverse cervical artery. In 2/10 arteries it was a direct branch of thyrocervical trunk. In other two cadavers suprascapular artery is a direct branch of transverse cervical artery. In two cadavers it is also a direct branch of subclavian artery.

Avergage length of transvserse cervical artery is 5.875 cm.

In the study by Ronald A Bergman60 found that Transverse cervical artery from subclavian Artery in 61%, from Thyrocervical trunk in 38%.He also stated that if Transverse cervical Artery is absent it is compensated by the branches of Dorsal scapular artery or costocervical trunk.

Study by Toyaharu15 found transverse cervical artery in 122/ 144.Among these 122 in 93 cases Transverse cervical artery arise from thyrocervical trunk.

44 In other cases they found origin of transverse cervical artery from second and third parts also.

In the study by Humberto et al45 found that 92.3% Transverse cervical artery from common trunk with suprascapular trunk. In 3.84% direct branch of inferior thyroid artery.In 3.84% it is a direct branch of thyrocervical trunk.

In the study done Tesler oren61 found transverse cervical artery is an optimal second line Recipient artery in head and neck reconstruction.

Anatomical locations, diameter and length of transverse cervical artery is found.

It arises from Thyrocervical trunk at an average distance of 17mm superior to clavicle. The mean length of artery is 4 to 7cm. In a clinical follow up in 19 cases, transverse cervical artery is recipient artery and no flap loss occurred in any of 19 cases.

In the study by Loganayagi et al46 found that Transverse cervical artery originating from Thyrocervical trunk in 59%.

In the study study by Benny Jose Panakkal et al62 observed in a patient while evaluating for chest pain. He observed bilateral variation of subclavian artery.

On left side internal Thoracic artery arose from common trunk. The common trunk also gave rise to transverse cervical artery and suprascapular artery. Inferior thyroid artery arose directly from subclavian artery. On right side

Internal thoracic artery arose from common trunk which gave branch to

45 suprascapular artery. Thyro cervical trunk had only two branches, inferior thyroid artery and transverse cervical artery.

In the study by Lopez et al49 transverse cervical artery was found in

40/40. Origin of transverse cervical artery from thyrocervical trunk in 32/40, from supra scapular artery in 6/40, directly from subclavian artery in 2/40.

In the study by Donald a Heulke63 transverse cervical artery from

Thyrocervical trunk in 77.5%.

In the study by Thompson64 transverse cervical artery from Thyrocervical trunk is seen in 86.9%.

10. SUPRASCAPULAR ARTERY

Naidoo et al65 did study on suprascapular artery. He observed that 80% of SSA passes over superior transverse Ligament. In 20% SSA passes inferior to

Transverse ligament. In that 20% classical origin of Suprascapular artery from thyrocervical trunk was recorded in 7% specimen. Rest 4% from third part of subclavian artery, first part of axillary artery 2%, second part of axillary artery

5%, from 2%.

Generally, arise from thyrocervical trunk that is branch of first part of subclavian artery. It provides muscular branches to subscapularis, sternocleidomastoid, and subclavius.80% of suprascapular artery pass over superior. Transverse scapular ligament.

46 In the study by Havet et al66 did study on vascular anatomical basis for clavicular non-union. In his study he found that Suprascapular artery gives off nutrient branches to clavicle. They have reported that suprascapular artery responsible for exclusive blood supply of middle third of clavicle.So knowledge of origin and its branches of suprascapular artery provides clinical knowledge for clavicular fracture.

In the study done by Toyaharu et al15 observed in 55cases Suprascapular artery branching from thyrocervical trunk with transverse cervical artery. In few cases from second, third part and even from axillary artery

N. Naidoo et al67 did study on variations of subclavian, axillary arterial

Tree. Naidoo et al found suprascapular artery from thyrocervical trunk in the first part of subclavian artery in 53%. suprascapular artery from third part of subclavian artery in 19%, from axillary artery in 17%.

In the study done by Adel k Afifi et al68 observed that suprascapular artery arise from Thyrocervical trunk in 92%, from Internal thoracic artery in

4.1%,from transverse cervical Artery, from subclavian artery in 2%.In rest suprascapular artery arise from Thyrocervical Trunk with Transverse cervical artery.

In the study A common trunk providing the suprascapular and the superficial cervical (also known as transverse cervical) artery has been described in 30% of the individuals, whereas in 28% of the cases both arteries arise directly

47 from the thyrocervical trunk (the transverse cervical artery, whenever it exists, provides both the superficial cervical and the dorsal Scapular artery.

According to classic anatomical textbooks, the suprascapular artery is the first (lower) branch of the thyrocervical trunk and runs transversely in the posterior cervical triangle, parallel, behind, and above the clavicle. The artery first courses laterally, in front of the scalene anterior muscle and the phrenic nerve and then crosses anterior to the third part of the subclavian artery and the primary cords of the brachial plexus Then, it continues backward ,reach the superior border of the scapula, where it normally passes over the superior transverse scapular ligament (STSL).By this way, it reaches the supraspinous fossa and continues to the infraspinous fossa through the spinoglenoid notch. At the dorsal scapula, it creates an important anastomotic network with the dorsal scapular artery (also known as deep branch of the transverse cervical artery) and the circumflex scapular branch of the subscapular artery. Normally, the suprascapular artery joins the suprascapular nerve near the middle half of the superior border of the scapula. The nerve passes under the STSL and through the , before entering the supraspinous fossa. At the dorsal scapula the suprascapular artery and nerve run together supplying the same targets (supraspinatus and infraspinatus muscles).The suprascapular notch is located at the superior border of the scapula, medial to the base of the coracoid process, and is converted into a foramen by the STSL.

48 The result of this study is origin of Suprascapular artery from thyrocervical trunk in all cases except one which had origin from First part of axillary artery.

In the study done by Lopez49 found that suprascapular artery from thyrocervical trunk in 24/40.Suprascapular artery arising from subclavian artery in 12/40 cadavers.

Study done by Mishra69 observed supra scapular artery usually a branch of thyrocervical Trunk. It passes across transversely over scalenus anterior

Muscle, brachial plexus and third part of subclavian artery. On reaching superior border of scapula it passes above superior Transverse ligament while nerve passes below ligament. In this study right side Suprascapular artery is branch of

Thyrocervical trunk. Left side Suprascapular artery is a branch of axillary artery.

He also compared the studies done by Bean (1905)-22% of suprascapular artery from third part of subclavian artery, REED and TROTT (1941)-28% of

Suprascapular artery from third part of Subclavian artery., majority from thyrocervical trunk. Left Suprascapular artery from axillary artery.

In the study done by Humberto et al45 found that 92.3% Suprascapular artery origin is from common trunk with Transvserse cervical artery. In 3.84% directly origin from Inferior thyroid artery. In 3.84% double Suprascapular artery was found.( one common trunk with DSA) .

49 In the study of Rajani singh70 found that suprascapular artery arises from first part of axillary Artery in one out of 28 limbs.

Lovesh shukla71 found bilateral variation in suprascapular artery.

Bilaterally suprascapular Artery arise from first part of axillary artery. SSA on both sides ascend for about 1cm above medial third of clavicle and passes obliquely behind clavicle. It also passes below trunks of brachial plexus to reach suprascapular notch accompanied by supra scapular nerve.

In a case report by Niladri72 found that suprascapular artery bilaterally a branch of third part of axillary artery.

Study done by Pyrgakis et al73 illustrated that suprascapular artery originated from third part of subclavian artery on right side in 1/62.

Jaishree H et al74 observed in a case suprascapular artery from first part of axillary artery. Unusual origin of suprascapular artery and piercing lateral cord of brachial plexus passing between Transverse scapular ligament cause compression of artery. Hence understanding of origin and branching pattern of suprascapular artery helps in management of cervical and shoulder region that could be due to vascular origin.

Dasler Anson75 did the study on branching pattern of subclavian arteries, he found that suprascapular artery from first part of subclavian artery in

81.5%,from third part of subclavian artery in 13.15%,from axillary artery is rare.

50 11. COSTO CERVICAL TRUNK

Study by Jhanshahi Mehrdad et al58 found that all the arteries arise from first part of subclavian Artery. Costocervical artery from a dorsal scapular artery, which is from a common trunk with transverse cervical artery.

In the study done by Toyaharu et al15 found in 65.3% costocervical trunk arises as a common branch for highest intercostal and deep cervical artery.

In 27.8% it arises as a separate branch for highest intercostal artery and deep cervical artery.

In the edition of latest term Philippe76 Costocervical artery arise as a short branch from subclavian artery giving two branches deep cervical artery and supreme intercostals artery.

In the study by Tanvaa Tansatit34 reported that costocervical trunk is seen in 92%. He also recorded a trunk having deep cervical artery and dorsal scapular artery in 1.6%.

12. DEEP CERVICAL ARTERY

In the study done by koizumi77 stated that small twig arise from second part of subclavian artery giving spinal branches and muscular branches to prevertebral muscles in 77% of Cases. The authors therefore propose the name deep ascending cervical artery. In this study in 22 cases the deep cervical artery

51 or costocervical trunk from first part had disappeared and was compensated by a branch of this deep ascending cervical artery.

In the study by Juwan Ryu16 found that deep cervical artery is present as separate branch from subclavian artery in 9% apart from deep cervical artery with highest intercostals artery. In his study he recorded that deep cervical artery is absent in 13%.

In the study done by Mehmapet Arslan et al78, observed that Ascending cervical artery typically arose from thyrocervical trunk, In this study mean diameter of these artery was measured. The deep cervical artery generally arose as one or more branches from costocervical trunk. In this study one from costocervical trunk and other directly from subclavian artery.

Accessory ascending artery was studied by Su Wd.Ohtsuka6 in 87

Japanese cadavers (174 sides). In 154 sides (88.5%), the accessory ascending cervical artery was found to originate from the subclavian artery behind the scalenus anterior muscle. This artery arose independently in 105 sides, accessory ascending cervical artery issued off or formed in a common trunk with the transverse cervical artery and/or costocervical trunk in 49 sides. In cases lacking the accessory ascending cervical artery, it was usually compensated by the costocervical trunk or transverse cervical artery (18 sides). Common trunk formation with the vertebral, internal thoracic, or suprascapular arteries was not observed. The authors suggest that the accessory ascending cervical artery, the

52 transverse cervical artery, and the costocervical trunk should be grouped into one arterial system, a system that may be a remnant of the precostal longitudinal anastomoses of intersegmental arteries of the dorsal aorta behind the scalenus anterior muscle.

In the study done by Ronald Bergman et al79 found that highest intercostal artery arises from internal thoracic artery in one case.

Dorsal scapular artery

In the study done by Lischka MF et al80 dorsal scapular artery is a direct branch of subclavian artery in 75%. In remaining dorsal scapular artery arise from thyrocervical trunk directly or via transverse cervical artery. According to them they stated that subclavian artery is most common site of origin of dorsal scapular artery.

In the study by Tanvaa Tansatit34 in Thai populations recorded that

Dorsal scapular artery from first part of subclavian artery in 55%, from costocervical trunk in 1.2%, from third part of subclavian artery in 30.86%.

In the study done by Chaijaroon khanarak Wunne81 studied about the dorsal scapular artery and its relation to brachial plexus in 252 side. The results are most commonly from TCA in 69%, followed by direct branching from second part of SCA in 2.8% or third part in 28.2%. When DSA is a branch of

TCA it passes above or posterior to brachial plexus. When it is from second or

53 third part it passes between trunks of brachial plexus. Most frequent course was to pass between upper and middle trunks (63.2%)

It arises from third part of subclavian artery. It passes between upper and middle trunks.

In the study done by Anne Marie et al82 observed that unusual dorsal scapular artery compresses the lower trunk which cause intermittent pain. Dorsal scapular artery originates from subclavian artery directly in 71%, from thyrocervical trunk in 35%. Typical dorsal scapular artery path is origin from subclavian artery passing between upper and middle brachial plexus (40%), between middle and lower trunks (23%), inferior or superior to brachial plexus

(1%).

Variability in relation between dorsal scapular artery and trunks of brachial plexus has surgical and clinical implications such as diagnostic of thoracic outlet syndrome.

In the study done by Anton Reiner83 said that dorsal scapular artery is subject to variation in their origin. Their study sought to clarify which is the common origin of dorsal Scapular artery. They found that dorsal scapular artery from subclavian in 75% and from transverse Cervical artery in 25%. Dorsal scapular artery from subclavian artery passes between upper and middle or middle and lower trunks. Those from transverse cervical artery course through levator scapulae before passing through rhomboid.

54 Study done by Ikka et al84 found that dorsal scapular artery either a direct branch of Subclavian artery or a branch of transverse cervical artery. He did both dissection and radiological study. In radiologic study found that Dorsal scapular artery and TCA had common origin from SCA in 57/93(type1), DSA direct branch of SCA in 22/93(type2), DSA and TCA common origin from TCT in

14/93(type3).

In the study done by Philip Manyacka85 did dissection in 58 regions. In

21 region dorsal scapular artery in common trunk with transverse cervical artery from first part of Subclavian artery. In 27 regions dorsal scapular artery arise directly from subclavian artery whereas transverse cervical Artery from thyrocervical trunk.

In the study done by Angirgani86 did the study on DSA on 28 cadavers and 32 clinical cases, the most common origin was dorsal scapular artery from

Transverse cervical artery .

In the study by Juwan Ryu16 recorded that dorsal scapular artery from third part in 57.2%.

In the study by Degaris87 found that Dorsal scapular artery from first part of subclavian artery in 45%, from costocervical trunk in 2.2% and from third part of subclavian artery in 52.1%

In the study done by Keith N. Bishop et al88 observed that Dorsal scapular artery follows to provide blood to trapezius,

55 levator scapulae and rhomboid muscles. Dorsal scapular artery spirals around dorsal scapular nerve as it runs medial to scapula and anterior to rhomoids.

Variation studied is dorsal scapular artery from subclavian artery is common

(75%), followed by indirect dorsal scapular artery from Thyrocervical trunk.

Course of artery also varies ,if it is a direct branch it passes between upper and middle trunks of brachial plexus. Indirect branch means passes above brachial plexus.

In the study done by Chaijaroonkhanarak Wunnee et al81 found dorsal scapular artery from three sites, from common trunk with transverse cervical artery in 69%, directly from second part -2.8%,third part 28%.dorsal scapular artery from transverse cervical artery always run posterior or above brachial plexus. Dorsal scapular artery from second or third part runs in branches of brachial plexus.

56 CHAPTER – IV MATERIALS AND METHODS

57

MATERIALS AND METHODS

Thirty embalmed cadavers from our institution in the Department of

Anatomy over the course of study, from October 2017 to May 2019,were dissected for the study purpose.

Study type: Dissection and Observation in human cadavers.

MATERIALS USED:

Materials, Instruments and Other accessories used:

• Stainless steel scalpel • Stainless steel long and short forceps—toothed and non-toothed. • Stainless steel straight and curved scissors. • Protective gadgets--Gloves and Apron and face mask • Digital camera. • Vernier callipers • Paint

Method used:

The procedure is done by following CUNNINGAM’S manual of Practical

Anatomy, Volume Three, Head and Neck and Brain, G.J.ROMANES, Oxford

Medical Publications, Fifteenth Edition, 1986, Reprinted, 2011.

58 DISSECTION PROCEDURE:

Dissection of superior mediastinum was done in cadavers in whom thoracic cavity not opened. Transverse incision through manubrium sternum just below level of first intercostal space. Ribs from 2-9 were cut at costochondral junction. Sternum was turned to upper part of abdominal wall. Fat tissue and pericardial covering over arch of aorta and great vessels were removed. Right and left brachiocephalic veins were gently cut.

Supra clavicular region was dissected. Skin and subcutaneous tissue was cut. superficial fascia reached, under superficial fascia, investing layer of deep cervical fascia was found .sternocleidomastoid, sternothyroid and sternohyoid muscles are exposed ,cut and reflected superiorly .

Fascial sling of intermediate tendon of was cut and reflected. Clavicle was cut at its length. Blood vessels are exposed, internal jugular vein (IJV) was identified and traced till its opening in subclavian vein.

Internal jugular vein was displaced medially to expose subclavian artery which was identified as a branch of brachiocephalic trunk on right side and from arch of aorta on left side. Branches of subclavian artery were identified.

59 CHAPTER - V OBSERVATIONS & RESULTS

60

OBSERVATIONS

1. Origin of subclavian artery:

Subclavian artery origin in the right and left from brachiocephalic trunk and arch of aorta respectively.

2. No of branches of Subclavian artery:

The usual branching pattern of subclavian artery is vertebral artery, internal thoracic artery, Thyrocervical trunk, Costocervical trunk, Dorsal scapular artery, totally five branches.

The five branching patterns of Subclavian artery was observed in nineteen subclavian arteries in right side.

In left five branches of Subclavian artery was observed in eighteen out of thirty Subclavian arteries. Four branches of subclavian artery were observed in

10 Subclavian arteries out of 30 arteries in right side. In left 11 Subclavian arteries were having four branches. (CHART1 ,TABLE1)

Table 1 : No of branches of Subclavian artery (SCA)

No of branches Right SCA Left SCA

Five branches 19(63.3%) 18(60%)

Four branches 10(33.3%) 11(36.6%)

61 Three branches 1(3.3%) 1(3.3%)

70%

60%

50%

40% Right SCA 30% Left SCA 20%

10%

0% 5 branches 4 branches 3branches

Chart1: Percentage of branches of subclavian artery

3. First part of subclavian artery:

From the first part of subclavian artery on the right side give rise to three branches namely vertebral artery, Internal thoracic artery, Thyrocervical trunk. the left side of Subclavian arteries give rise to four branches namely vertebral artery, Internal thoracic artery, Thyrocervical trunk, Costocervical trunk.

(Table 2)

Table 2: Branches of first part

No of branches Right Left

Three 30 1(3%)

Four - 29(97%)

62

In the present study thirty subclavian artery on right side have three branches. The left subclavian artery which is having four branches were seen on

29 Arteries (97%). One artery on the left side having three branches (3%), vertebral artery was not present in the first part of subclavian artery.

Vertebral artery

4. Origin of Vertebral artery:

In right 30 vertebral artery originated from right brachiocephalic trunk. In left 29 (97%) vertebral artery arises from left subclavian artery, one artery (3%) arise from arch of aorta. (Figure 1, Table 3)

Table 3 : Origin of vertebral artery

Side Origin from subclavian Origin from AOA

Right Thirty - Left Twenty-nine (97%) One (3%)

5. Length of prevertebral segment of vertebral artery:

The mean length of 30 vertebral artery on right side is 4.1cm, the mean length of 30 vertebral artery on left side is 3.8cm.one of the left vertebral artery which arise from arch of aorta is longest which is 8.8cm.

63 Table 4 : Level of vertebral artery entering transverse foramina

Vertebral artery entry level Right Left

At C6 level 30 29(97%) At higher level(C4) - 1(3%)

In the vertebral arteries of right side 30 entered the normal C6 foramen transversorium. On the left side 29 vertebral arteries entered C6 foramen transversorium (97%). One artery (3%) which arises from Arch of aorta entered at higher level C4 vertebra..(Table 4)

Internal Thoracic artery:

5. Origin of internal thoracic artery: Origin of 29 internal thoracic artery of right side arise from first part. It arises from inferior aspect of subclavian artery. 30 internal thoracic arteries from left side arise from first part of subclavian artery. One artery from right side arose from a common trunk with

Thyrocervical trunk. (Fig 2, Table 5)

Table 5: Origin of internal thoracic artery

Origin of internal thoracic Artery Subclavian artery Other source

Right 29(97%) 1(3%) Common trunk with TCT

Left 30 -

64

Fig 1: Vertebral artery from Arch of Aorta(SCA-Subclavian artery)

65

Fig 2: Internal Thoracic artery from thyrocervical trunk TCT

66 6. Thyro-cervical trunk:

Branches of thyro-cervical trunk is three namely, inferior thyroid artery, transverse cervical artery (TCA), suprascapular artery. Three branching patterns on right side was present in 23/30 subclavian arteries. (Table 6, Chart 2)

One of the usual branches suprascapular artery (SSA) is absent in 9/30

Thyrocervical trunk (TCT) (third branch was ascending cervical artery).

In left side 22/30 Thyrocervical trunk are having three branches, of these

22 Thyrocervical trunk, in four Thyrocervical trunk –suprascapular artery is absent (third branch was ascending cervical artery).

The next type was Thyrocervical trunk having two branches from common stem namely inferior thyroid artery and ascending cervical artery was seen in 6/30 on right side and 4/30 on left side. (Figure 3)

Four branches of Thyrocervical trunk was found in 1/30 on right side and

2/30 on left side. Four branches found was Inferior Thyroid Artery, ascending cervical artery, Transverse cervical artery and Suprascapular artery.

Five branches of Thyrocervical trunk was found in 1/30 on left side. Five branches are namely inferior thyroid artery, ascending cervical artery, transverse cervical artery, uprascapular artery, internal thoracic artery. No such number of branches were present in right side. (figure 4)

67 In one Subclavian artery on left side Thyrocervical trunk is absent but the branches Inferior thyroid artery, arise as direct branch from Subclavian artery.

(Figure 5) Infundibular dilatation is seen in 1/30 thyrocervicalt trunk on left side which is having five branches.

Table 6: No of branches of Thyrocervical trunk

Left (out of 30, in one No of branches of TCT Right TCT is absent)

Two 6/30(21%) 4/30(13%) Three 23/30(76%) 22/30(71%) Four 1/30(3%) 2/30(6%) Five - 1/30(3%)

80%

70%

60%

50%

40% right left 30%

20%

10%

0% Two branches Three branches Four branches five branches

Chart 2: Percentage of branches of Thyrocervical trunk

68

Figure 3: Thyro cervical trunk with two branches

69

Figure 4 : Thyrocervical trunk with five branches

70

Figure 5: Inferior Thyroid artery from Subclavian artery, Thyrocervical trunk absent.

71 7. Inferior thyroid artery:

Inferior thyroid artery in all the 30 subclavian arteries right and left arise from first part of subclavian artery. Inferior thyroid artery arises from

Thyrocervical trunk in all 30 arteries on right side. In left side 29 inferior thyroid arteries from Thyrocervical trunk, one directly from Subclavian artery. (Figure

5, Table 7)

Table 7: Origin of inferior thyroid artery

Origin of inferior thyroid artery TCT Other source

Right 30 - Left 29(97%) 1 Directly from first part of SCA (3%)

8. Relation of inferior thyroid artery with recurrent laryngeal nerve:

Relation of inferior thyroid artery with Recurrent laryngeal nerve in 30 subclavian arteries, in right side is 12 artery was anterior to Recurrent laryngeal nerve, 4 arteries deep to Recurrent laryngeal nerve, 15 arteries were giving branches, in-between branches of Inferior thyroid artery, Recurrent laryngeal nerve Present.(Figure 6.Table 8)

In 30 subclavian arteries on left side,16 arteries were anterior to Recurrent laryngeal nerve,6 arteries were deep to Recurrent laryngeal nerve, in-between the branches of 8 inferior thyroid artery Recurrent laryngeal nerve is present.

72 Table 8 : Relation of Recurrent laryngeal nerve to Inferior Thyroid Artery

Relation of RLN to Inferior thyroid artery Right Left

Superior to Inferior thyroid artery 4(12%) 6(21%)

Deep to inferior thyroid aretery 12(37%) 16(51%)

Between branches of inferior thyroid artery 14(51%) 8(28%)

60%

50%

40%

30% Right left 20%

10%

0% RLN superior to ITA RLN Inferior to ITA RLN btw branches of ITA

Chart 3: Relation of recurrent laryngeal nerve with Inferior thyroid artery.

RLN -Recurrent laryngeal nerve, ITA-Inferior thyroid artery

On both side relation of recurrent laryngeal superior to inferior thyroid artery in 16%, deep to inferior thyroid artery in 46%, between the branches of inferior thyroid artery in 36%.(chart 3)

73

Figure 6 : Relation of Recurrent laryngeal nerve between the branches of Inferior thyroid artery

74 9. TRANSVERSE CERVICAL ARTERY:

Transverse cervical artery is one of the branches of Thyrocervical trunk.

Transverse cervical artery one of the branches of Thyrocervical trunk in 24 arteries on right side, absent in six arteries. (Table 9)

In left side Transverse cervical artery is present in Thyrocervical trunk of subclavian arteries in 25 arteries, absent in five Thyrocervical trunk. (chart 4)

Table 9: Presence / absence of Transverse cervical artery

Transverse cervical artery Right Left

Present 24(80%) 25(83%)

Absent 6(20%) 5(17%)

90% 80% 70% 60% 50% right 40% left 30% 20% 10% 0% present Absent

Chart 4: Transverse cervical artery Presence / Absence

75 10. Suprascapular artery:

Suprascapular artery is one of the branches of Thyrocervical trunk.It arises from first part of Subclavian arteries in 18 Thyrocervical trunk on the right side. Nine Suprascapular artery also arise from third part of Subclavian artery.

(Figure 7, Table 10)

In one Subclavian artery, Suprascapular artery is absent, but it is seen in first part of axillary artery in right side (Figure8).

On the left side 21 Suprascapular artery is from Thyrocervical trunk. 4

Suprascapular artery arise from third part of Subclavian artery, five

Suprascapular artery was seen to be originating from first part of axillary artery.(Chart 5)

Table 10 : Origin of Suprascapular artery

Suprascapular artery Right Left Percentage

First part 18(60%) 21(70%) 65 Third part 9(30%) 4(13.3%) 21.6

Axillary a. 3(10%) 5(16.6%) 13.3

76 80%

70%

60%

50%

40% Right Left 30%

20%

10%

0% Firstpart third part Axillary artery

Chart 5: Origin of suprascapular artery

11. Second part of Subclavian artery:

Costo cervical trunk arises from first part in left side and from second part in right side.

12. Costo cervical trunk:

The branches of Costocervical trunk are deep cervical artery and highest intercostal artery.

77

Figure 7: Supra Scapular artery from third part of Subclavian artery. (SSN-Suprascapular Nerve)

78

Figure 8: Supra Scapular Artery from Axillary Artery(a-Artery)

79 Table 11: Branches of Costocervical trunk

DCA from trunk DCA direct branch DCA absent SCA Right Left Right left Right Left First part - 19(63.3%) - 7(23.3%) - 4(13.3%) Second 20(66.6%) - 4(13.3%) - 6(20%) part DCA-Deep cervical artery

In 30 Subclavian arteries on the right side 20 deep cervical artery is seen in the trunk. Among 20, 19 deep cervical artery is present along with highest intercostal artery. One trunk with Dorsal scapular artery. Four Deep cervical artery (DCA) as a single branch directly from Subclavian artery, Deep cervical artery is absent in six Subclavian arteries. (Table 11)

Totally 19 trunks are seen on the left Subclavian artery, On the left Deep cervical artery is present as a trunk with highest intercostal artery in 18 trunks. In one trunk ,Deep cervical artery is forming trunk with dorsal scapular artery

(DSA). Seven Deep cervical artery, arise as a direct branch of Subclavian artery.

In four Subclavian arteries, deep cervical artery is absent.

13. Third part of Subclavian artery:

The Branches of third part of Subclavian artery is either Dorsal scapular artery or Suprascapular artery in 80% of arteries. In the remaining 20% third part does not have arteries. (Table 12)

80 Table 12 : Presence/Absence of branches in third part of subclavian artery

Third part Right Left Percentage

Br. Present 26 22 80% Br. Absent 4 8 20%

14. Dorsal Scapular artery:

Dorsal scapular artery arise from third part of Subclavian artery, also it arises from first part and sometimes from second part.

Table 13: Origin of Dorsal scapular artery

DSA origin Right Left Percentage

Thyrocervical trunk 11 9 33.3%

Costo cervical trunk 1 1 3.3%%

Third part 17 18 58.3% Axillary artery 1 2 5%

On right side Dorsal scapular artery arise from Thyrocervical trunk of

Subclavian artery in 11 arteries. It also arose from costocervical trunk in one subclavian artery.

On the right side from third part, in 17 Subclavian artery, absent in one

Subclavian artery but present in axillary artery. (Table 13,Chart 6)

In the left side 10 Dorsal scapular artery from first part i.e. 9 arteries from

Thyrocervical trunk and one from Costocervical trunk (Figure 9). From third part of subclavian artery in 18 arteries.Dorsal scapular artery absent in 2 Subclavian arteries but present in axillary arteries.

81

Figure 9: Dorsal Scapular artery from cervico scapular trunk

82 70.00%

60.00%

50.00%

40.00%

30.00% DSA origin 20.00%

10.00%

0.00% Thyrocervical CCT third part Axillary artery trunk

Chart 6: Percentage of Dorsal scapular artery (DSA) origin

15. Relation of Dorsal scapular artery to Brachial plexus:

Relation of Dorsal scapular artery to brachial plexus is, artery from third part or axillary artery runs between trunks of brachial plexus or below the trunks of brachial plexus. (Figure 10 Table 14)

Dorsal scapular artery from first part runs above brachial plexus.

Table 14: Relation of dorsal scapular artery to brachial plexus

Relation of dorsal scapular artery Right Left

Above brachial plexus 12(40%) 9(30%)

Between /below trunks of Brachial plexus 18(60%) 21(70%)

83

Figure 10 : Dorsal scapular artery (DSA) running below trunks of brachial plexus

84 80%

70%

60%

50%

40% Right 30% Left 20%

10%

0% Abv Brachial plexus Btw or Blw Brachial plexus

Chart 7: Relation of dorsal scapular artery with Brachial plexus. DSA-Dorsal scapular artery;btw-between Blw-Below.

85 MASTER CHART

Origin Vertebral artery TCT Inferior thyroid A DSA Length Internal Deep- of sub Asc.cervical Rltn to S. of SCA thoracic NO. of Rltn of TCA SSA cervical clavian Origin Length Origin Origin A Origin brachial NO (cm) artery branches RLN artery artery plexsus Rt Lt Rt Lt Rt Lt Rt Lt Rt Lt Rt Lt Rt Lt Rt Lt Rt Lt Rt Lt Rt Lt Rt Lt Rt Lt Rt Lt Rt Lt B A S S S T T A A T T 1st 1st Abv Abv 1 C O 6.1 8.1 C C 4.8 4.1 SCA C 2br 2br C C Sup Sup P P X X A A P P C C part part Trunk trunk T A A A A T T A A T T B A S S S T T A T T 1st 1st 3rd Abv Abv 2 C O 6.2 8.3 C C 4.7 4.2 SCA C 3br 3br C C Deep Deep P P X A A P P C C part part part trunk trunk T A A A A T T A T T B A S S S T T A T 1st 1st 3rd Abv Btw 3 C O 6.3 8.5 C C 4.8 4.1 SCA C 3br 3br C C Deep Deep A P X P P A A C 3rd part part part trunk trunk T A A A A T T A T B A S S S T T T T 1st 1st Btw Btw 4 C O 5.9 8.7 C C 4.7 4.1 SCA C 3br 3br C C Deep Deep P P C C A A P P 3rd 3rd part part trunk trunk T A A A A T T T T B A S S S T T T T 1st 1st Btw Btw 5 C O 5.6 8.1 C C 4.9 4.2 SCA C 3br 3br C C Sup Btwbr P P C C P P A A 3rd 3rd part part trunk trunk T A A A A T T T T B A S S S T T T T 1st 1st 3rd 3rd Abv Abv 6 C O 6.2 8.4 C C 4.5 4.8 SCA C 3br 3br C C Btwbr Sup P P A A P P C C part part part part trunk trunk T A A A A T T T T B A S S Common S T T T T 1st 1st Btw Btw 7 C O 5.6 8.3 C C 4.8 4.2 trunk C 3br 4br C C Btwbr Btwbr A A C C A A P P 3rd 3rd part part trunk trunk T A A A with TCT A T T T T

86 Origin Vertebral artery TCT Inferior thyroid A DSA Length Internal Deep- of sub Asc.cervical Rltn to S. of SCA thoracic NO. of Rltn of TCA SSA cervical clavian Origin Length Origin Origin A Origin brachial NO (cm) artery branches RLN artery artery plexsus Rt Lt Rt Lt Rt Lt Rt Lt Rt Lt Rt Lt Rt Lt Rt Lt Rt Lt Rt Lt Rt Lt Rt Lt Rt Lt Rt Lt Rt Lt B A S S S T S A A C C 1st 1st 8 C O 6.1 8.7 C C 4.7 4.1 SCA C 2br absent C C Deep Deep P P X X A A P P C C Blw Blw part part T A A A A T A A A T T B A S S S T T T T 1st 1st Btw Btw 9 C O 6.2 8.1 C C 4.5 3.9 SCA C 4br 4br C C Btwbr Deep P P C C p P A A 3rd 3rd part part trunk Trunk T A A A A T T T T B A S A S T T T T 1st 1st Btw Btw 10 C O 6.3 8.2 C O 4.4 8.8 SCA C 3br 3br C C Btwbr Deep A A C C A A P P 3rd 3rd part part trunk Trunk T A A A A T T T T B A S S S T T T T T 1st 1st Abv Abv 11 C O 6.4 8.4 C C 4.8 4.5 SCA C 3br 3br C C Sup Sup P P 3rd C p P A A C C part part trunk Trunk T A A A A T T T T T B A S S S T T T T 1st 1st Btw Btw 12 C O 6.1 7.7 C C 4.7 4.2 SCA C 3br 5br C C Btwbr Deep P P C C A A P P 3rd 3rd part part trunk Trunk T A A A A T T T T B A S S S T T T T 1st 1st 3rd 3rd Abv Abv 13 C O 6.2 8.2 C C 4.8 3.9 SCA C 3br 3br C C Btwbr Deep P P P P A P C C part part part part trunk Trunk T A A A A T T T T B A S S S T T T T 1st 1st 3rd Abv Btw 14 C O 6.3 8.3 C C 4.6 4.6 SCA C 3br 2br C C Deep Btwbr A A C A A P P C 3rd part part part trunk Trunk T A A A A T T T T B A S S S T T T T 1st 1st Btw Btw 15 C O 6.1 8.1 C C 4.5 4.7 SCA C 3br 3br C C Btwbr Deep A A C C A A P P 3rd 3rd part part trunk Trunk T A A A A T T T T

87 Origin Vertebral artery TCT Inferior thyroid A DSA Length Internal Deep- of sub Asc.cervical Rltn to S. of SCA thoracic NO. of Rltn of TCA SSA cervical clavian Origin Length Origin Origin A Origin brachial NO (cm) artery branches RLN artery artery plexsus Rt Lt Rt Lt Rt Lt Rt Lt Rt Lt Rt Lt Rt Lt Rt Lt Rt Lt Rt Lt Rt Lt Rt Lt Rt Lt Rt Lt Rt Lt B A S S S T T T T 1st 1st Btw Btw 16 C O 6.2 7.7 C C 4.8 4.8 SCA C 3br 3br C C Btwbr Sup P P C C p P A P 3rd 3rd part part trunk Trunk T A A A A T T T T B A S S S T T T T 1st 1st Btw Btw 17 C O 6.3 8.1 C C 4.4 4.7 SCA C 3br 3br C C Btwbr Btwbr P P C C A A P P 3rd 3rd part part Trunk trunk T A A A A T T T T B A S S S T T T T 1st 1st Btw Btw 18 C O 5.9 8.2 C C 4.5 4.5 SCA C 3br 3br C C Btwbr Deep P P C C A A P P 3rd 3rd part part Trunk trunk T A A A A T T T T B A S S S T T T T 1st 1st Btw Btw 19 C O 6.1 8.3 C C 4.8 4.4 SCA C 3br 3br C C Btwbr Deep P P C C A A P P 3rd 3rd part part Trunk trunk T A A A A T T T T B A S S S T T T T 1st 1st 3rd 3rd Abv Abv 20 C O 5.9 7.7 C C 4.5 4.5 SCA C 3br 3br C C Deep Sup P P A A P P C C part part part part Trunk trunk T A A A A T T T T B A S S S T T T T 1st 1st Btw Btw 21 C O 6.1 7.9 C C 4.5 4.6 SCA C 3br 3br C C Deep Deep P P C C A A P P 3rd 3rd part part Trunk trunk T A A A A T T T T B A S S S T T T T 1st 1st Btw Btw 22 C O 6.2 8.1 C C 4.8 4.8 SCA C 3br 3br C C Sup Sup A A C C A A P P 3rd 3rd part part Trunk trunk T A A A A T T T T B A S S S T T T T 1st 1st Btw Btw 23 C O 6.3 8.2 C C 4.7 4.7 SCA C 3br 3br C C Btwbr Deep P P C C A A P P 3rd 3rd part part Trunk trunk T A A A A T T T T

88 Origin Vertebral artery TCT Inferior thyroid A DSA Length Internal Deep- of sub Asc.cervical Rltn to S. of SCA thoracic NO. of Rltn of TCA SSA cervical clavian Origin Length Origin Origin A Origin brachial NO (cm) artery branches RLN artery artery plexsus Rt Lt Rt Lt Rt Lt Rt Lt Rt Lt Rt Lt Rt Lt Rt Lt Rt Lt Rt Lt Rt Lt Rt Lt Rt Lt Rt Lt Rt Lt B A S S S T T T T A A 1st 1st Btw Btw 24 C O 5.9 8.3 C C 4.6 4.5 SCA C 2br 3br C C Btwbr Deep P P C C A A P P X X part part Tunk tunk T A A A A T T T T A A B A S S S T T T T T 1st 1st 3rd Abv Abv 25 C O 6.1 8.3 C C 4.8 4.5 SCA C 2br 3br C C Deep Deep P P C A A P P C C part part part Trunk trunk T A A A A T T T T T

B A S S S T T A T 1st 1st A Abv Btw 26 C O 6.2 8.2 C C 4.8 4.5 SCA C 3br 2br C C Deep Deep P P X A A P P C 3rd part part X Trunk trunk T A A A A T T A T A B A S S S T T T T T 1st 1st Btw Abv 27 C O 6.3 8.1 C C 4.8 4.6 SCA C 2br 3br C C Deep Btwbr P P C C A A P P 3rd C part part Trunk trunk T A A A A T T T T T B A S S S T T T T 1st 1st Btw Btw 28 C O 6.3 8.1 C C 4.7 4.1 SCA C 3br 3br C C Deep Btwbr P P C C A A P P 3rd 3rd part part Trunk trunk T A A A A T T T T B A S S S T T T T 1st 1st 3rd 3rd Abv Abv 29 C O 6.2 8.3 C C 4.6 3.7 SCA C 3br 2br C C Deep Btwbr P P A A P P C C part part part part Trunk trunk T A A A A T T T T B A S S S T T T T A 1st 1st Btw Btw 30 C O 6.1 8.3 C C 4.7 3.8 SCA C 2br 3br C C Btwbr Btwbr P P C C A A P P 3rd X part part Trunk tunk T A A A A T T T T A BCT-Brachiocephalic trunk,AOA-arch of aorta,SCA-subclavin artery,Btw-between,Blw-Below,Abv-above,A-absent,P-Present, AX.A.-axillary artery.

89 CHAPTER - VI

DISCUSSION

90 DISCUSSION

1. Origin of subclavian artery:

Subclavian artery origin is from right brachiocephalic on the right and from arch of aorta in the left side. In the current study there was no abnormality in the origin in 30 subclavian arteries on the right and left.

2. Number of branches of subclavian artery:

The number of branches originating from Subclavian artery on each side is categorised. According to Henry Gray14 the number of branches from first part on the right side is three branches namely vertebral artery, internal thoracic artery, from second part Costo cervical trunk and from third part Dorsal scapular artery. So totally five branches were observed.

In the study by Juwan Ryu16 also found the arteries having five branches were more compared to four number of branches. The number of branches in the present study is shown in (Chart 1, Table 1) .

In the current study five branches of Subclavian artery was seen in nineteen arteries on the right side and eighteen arteries on the left side. In 62.6% five branching pattern was seen. Remaining were four branching pattern in 35%, three branching pattern in 3%.

91 3. Vertebral artery:

Dasler Anson32 also have reported the incidence of vertebral artery from aorta 1 to 3%. In the study done by Adachi and Yamaki31, the origin of vertebral artery from Arch of aorta is 5.4% and 5.8%.

Origin of vertebral artery from aortic origin have been documented by different authors with range of 3.1%-8.3%. No variants were observed in origin of right vertebral artery.

In the present study 60 vertebral arteries of right and left, 30 arteries on right and 29(97%) arteries on left, originate from subclavian artery. One vertebral artery (3%) from left side arise from aortic arch (Table 15 chart 8).The current study correlates with the study by DASLER.

Table 15: Comparison of vertebral artery origin

Aortic origin of vertebral artery Percentage Adachi 1928 5.4% ASSON 1932 3.2 Lippat 3 Vorstan 3 Yamaki 5.8% Present study 3%

92 6.00%

5.00%

4.00%

3.00% VA aortic origin

2.00%

1.00%

0.00% Adachi ASSON vorsatan Present study

VA-vertebral artery Chart 8: Comparison of study of vertebral artery origin.

Left vertebral artery from aortic origin may be because of persistence of dorsal division of left sixth intersegmental artery which continues as first part of vertebral artery, instead of left 7th intersegmental artery.

The embryological reason is persistence of the sixth intersegmental artery which links the longitudinal channel of left vertebral artery with aortic arch leads to the left vertebral artery arising from the aortic arch. Variant origin should be considered before misinterpreting non visualisation of Vertebral artery from its usual Location during investigation.

4. Length of prevertebral segment of vertebral artery:

In the study done by Tardiue et al28 found that vertebral artery arising from arch of aorta ascends more medially prone for iatrogenic injury. He also

93 stated that those arteries enter more cranially than usual c6 vertebrae. So surgeons should be aware of aortic origin of vertebral artery.

In the retrospective study done Chian Ling yung89 found that vertebral having aortic origin there is significance higher rate of anomalous entrance level.

In the current study all the vertebral arteries, the prevertebral segment was between the range of 3.3cm to 4.5cm but in the cadaver from aortic origin it was 8.8cm which is the longest and the course is also superficial.

The artery does not enter normalC6 vertebra, it enters much higher level at C4.

5. Internal thoracic artery (ITA):

Internal thoracic artery is widely used as a coronary artery bypass graft.

Internal Thoracic artery location such as distinct intrathoracic course, anatomical vicinity within heart, long term patency, good survival rate renders it as excellent graft for myocardial revascularisation.

A case study done by George Parsekavaos41 showed that left internal thoracic artery from Thyrocervical trunk was detected.

In the study done by Toyaharu et al15 found internal thoracic artery from

Thyrocervical trunk in 3.5%. In the current study Internal thoracic artery from

Thyrocervical trunk is found to be around 5% (Table 5).

94 The study done Lischka42 found that Internal thoracic artery from

Thyrocervical trunk around 10%.

The study done by Umeura44 and Nizamawaski43 also found the abnormal origin of Internal thoracic artery from Thyrocervical trunk.

The present study correlates well with the study by Toyaharu15. (Chart 9)

12%

10%

8%

6% ITA from TCT

4%

2%

0% Lischka Toyaharu current study

Chart 9: Comparative chart of origin of Internal Thoracic artery from Thyrocervical trunk.

In the present study abnormal Internal thoracic artery was seen in left side, it is risky in that severe blood flow diversion can occur resulting in coronary steal phenomena, leading to pain and restricted shoulder movements.

The awareness of such Internal thoracic artery origin is essential for thoracic and cardiovascular surgeons in order to avoid postoperative discomfort.

95 6. Thyrocervical trunk:

In the study done by Loganayagi et al46 the incidence percentage of 3 branches of first pattern is 61.5%, in the same study two branch pattern is seen in

5%, Thyrocervical trunk absent in 5%. In the study by Toyaharu15 two branching pattern is seen in 11.1%.

Five branch patterns were reported in a case study by Mariana

Branatuszowa.48 In the study done by Lopez 49three branch pattern is seen in

40%, four branching patterns were seen in 14.5%.two branch pattern seen in

50%, absence of TCT in 9%.

The study done by Lopez49 states that two branching patterns is more whereas Dasler Anson32 stated that 3 branching patterns is more.

In the current study three branches of Thyrocervical trunk was seen in

56.6%. The next pattern was Thyrocervical trunk having two branches are seen in 16.6%. Four branches of Thyrocervical trunk was also seen one on the right and two on the left. The percentage of incidence is 5%.

Five branches of Thyrocervical trunk was seen in one TCT on the left.

(1.6%). In one (1.6%) of the Subclavian artery on the left side Thyrocervical trunk is absent, branches arise directly.

96 This current study correlates well with the study of Loganayaki46 in three branching patterns. In two branching patterns the present study correlates well with the study by Toyaaharu15. (Chart 10)

Of all the branches inferior thyroid artery from thyrocervical trunk is the least to show the variability in its origin.

18%

16%

14%

12%

10%

8%

6%

4%

2%

0% Loganayagi Toyaharu present study

Chart 10: Comparative study of Thyrocervical trunk having two branches.

7. Inferior Thyroid Artery:

Inferior thyroid artery is one of the branches of Thyrocervical trunk. In the study by Elissa47 found that thyrocervical trunk is absent but the branches, inferior thyroid artery arise directly from subclavian artery of this type.

In the study done by Loganaygi46 Inferior thyroid artery as a direct branch in 5%. Similar to the above study, in the current study Inferior thyroid artery as a direct branch in 1.6%.

97 To avoid injury to recurrent laryngeal nerve during thyroid surgery thorough knowledge of recurrent laryngeal nerve and its relations with inferior thyroid artery is needed.

In the study done by Thilagavathi et al55 recurrent laryngeal nerve posterior to artery is 37%.

Recurrent laryngeal nerve anterior to artery is 11%. Recurrent laryngeal nerve between branches of Inferior thyroid artery is 51%.

In the study by Kumari et al56 10% Recurrent laryngeal nerve superior to artery, 80% Recurrent laryngeal nerve deep to artery. Recurrent laryngeal nerve between branches of inferior thyroid artery in 10%.

In the PRESENT study Recurrent laryngeal nerve between branches of

Inferior thyroid artery is 51%, posterior to Inferior thyroid artery is 29%.

Recurrent laryngeal nerve anterior ton Inferior thyroid artery is 21%. (Table 8)

This study correlates well with the study of Thilagavathi et al55.

(Chart11)

Inferior thyroid artery is one of the important source of blood supply to thyroid gland. Knowledge about origin and any accessory branches of

INFERIOR THYROID ARTERY will be definitely helpful to surgeons while performing thyroid surgeries.

98

90%

80%

70%

60%

50% thilagavathi 40% kumari present study 30%

20%

10%

0% RLN post to a. RLN ant to a. RLN btw br

Chart11: Relation of Recurrent laryngeal nerve with inferior thyroid artery

8. Transverse cervical artery (TCA):

Transverse cervical artery one of the branches of Thyrocervical trunk.

Many head and neck reconstruction surgery occur in patients with extensive history of surgery and radiations. For these flap reconstructions is needed. For the Flap reconstructions Transverse cervical artery is used as a recipient vessel.

In the study done by Ronald A Bergman60 observed if Transverse cervical artery is absent, it is compensated by the branches of Dorsal scapular artery and Cost cervical trunk.

In the study done by Donald Heulke63 it is found that transverse cervical artery from thyrocervical trunk is seen in 77.5%, and in the study by Thomson64 transverse cervical artery from thyrocervical trunk is seen in 86.9%.

99 The study done by Loganayaki et al46 found to Transverse cervical artery from Thyrocervical trunk in in 59%.

In the present study Transverse cervical artery from Thyrocervical trunk is seen in 81%. (Table 9)

The current study correlates well with the study done by Thomson64

(chart 12) transverse cervical artery can be easily accessed safely and efficiently as transverse cervical artery at the junction of upper limb and thorax, so it is used as a recipient vessel, for flap reconstructions.

100.00% 90.00% 80.00% 70.00% 60.00% 50.00% TCA from TCT 40.00% 30.00% 20.00% 10.00% 0.00% Donald Heulke Thomson Loganaygi Present study

Chart 12: Comparative chart on origin of Transverse cervical artery from Thyrocervical Trunk.

100 9. Suprascapular Artery (SSA):

Suprascapular artery is one of the branches of Thyrocervical trunk.

Suprascapular artery irrigates tendinous cuff of . Suprascapular artery irrigated middle third of clavicle (Havet66 clavicle non-union).

In the study done by Dasler Anson75 found that suprascapular artery from first part in 81.5%, suprascapular artery from third part of Subclavian artery in

13.15% and branching of suprascapular artery from Axillary artery is rare.

In the study done by Mishra69 branching of suprascapular artery from axillary artery is 1.6%.

In the study done by N Naidoo67 et al on variations of subclavian axillary

Arterial tree found that suprascapular artery from Thyrocervical trunk is found from first part of Subclavian artery in 53%, from third part of Subclavian artery in 19%, from axillary artery in 17%.

In the current study suprascapular artery from Thyrocervical trunk is 65%, from third part of Subclavian artery is 26%, from Axillary artery in 13%.

The present study correlates well with the study done by Naidoo67.

(chart13) Suprascapular artery is the main arterial supply for muscle, so the study on variations of suprascapular artery will help in the management of diseases from cervical and shoulder region.

101 70.00%

60.00%

50.00%

40.00% first part SCA third part SCA 30.00% Axillary a. 20.00%

10.00%

0.00% Naidoo presentstudy

SCA-Subclavian artery Chart 13: Comparative chart for various sites for origin of suprascapular artery

10. Costo cervical trunk:

In the study by Toyaharu15 Costo cervical artery is present in 66.7%, deep cervical artery arises as a separate branch in 27.8%.

In the study by Tanvaa Tansatit34 in Thai population reported Costo cervical artery in92%

In the study done by Koizumi77 said that 22 out of 130 Subclavian arteries (16.9%) deep cervical, artery is absent compensated by ascending cervical artery.

In the study done Juwan Ryu16 deep cervical artery is present as a separate branch from Subclavian artery in 9%, apart from common trunk with highest intercostal artery which is 78%. Deep cervical artery is absent in 13%.

102 In the current study on the right and left side deep cervical artery, along with highest intercostal artery seen as a trunk in 61.67%. (Table 11)

Deep cervical artery along with Dorsal scapular artery seen as a trunk in

3.3%, deep cervical artery as direct branch of SCA is seen in 18.3% and deep cervical artery absent in 16.6%.(chart7)

The current study correlates well with the study by Toyaharu

Takafugi15, deep cervical artery along with Dorsal scapular artery as a trunk is reported in a study by Tanvaa Tansatit34 (Thai) in 1.6% .

In the aspect of absence of Deep cervical artery, the current study correlates with study done by Koizumi 77 (chart 14)

18.00%

16.00%

14.00%

12.00%

10.00%

8.00% absence of DCA

6.00%

4.00%

2.00%

0.00% koizumi Juwan ryu present study

Chart 14: Comparative chart for absence of Deep cervical artery

103 11. Third part of subclavian artery:

Normally from third part of Subclavian artery, dorsal scapular artery arises, sometimes Suprascapular artery also arise.

In the present study 80% Subclavian artery has branch in third part. In

20% of subclavian artery third part does not have any branch.

In a case report by Jahanshahi Mehrdad58 there was no artery from third part of Subclavian artery.

12. Dorsal scapular artery (DSA):

Dorsal scapular artery arises from third part of subclavian artery. Dorsal scapular artery supplies levator scapulae and rhomboidus muscle, contribute to arterial anastomoses around scapula.

In the study done by Tanvaa Tansatit34 in Thai population Dorsal scapular artery from first part of subclavian artery in 55%, from Costo cervical trunk in 1.2%, from third part of subclavian artery in 30.86%.

In the study by Juwan Ryu16 Dorsal scapular artery from third part in

57.2%. In the study done by Degaris87 it is found that Dorsal scapular artery from first part of Subclavian artery in 45%, from Costo cervical trunk in 2.2% and from third part of Subclavian artery in 52.1%.

104 In the current study Dorsal scapular artery from first part of subclavian artery in 33.3%, from Costo cervical trunk in 3.3%, from third part of subclavian artery in 58.3% and from axillary artery in 5%. (Table 13)

The current study correlates with the study done by Juwan Ryu16 and

Degaris87. (chart 15).

70%

60%

50%

40% first part SCA 30% Axis Title Axis CCT 20% Third part

10%

0% Degaris TanvaTansatit Present study Axis Title

Chart 15: Origin of Dorsal Scapular Artery

Dorsal scapular artery provides reliable blood supply for the skin of back making it as a versatile flap to be used as an island flap. A flap raised on Dorsal scapular artery can be harvested with long pedicle and can be rotated to reach anterior region of head and neck.

So, the variation in origin of Dorsal scapular artery will be helpful for plastic surgeons.

105 Dorsal scapular artery relation to brachial plexus, Dorsal scapular artery arising from first part runs above or below the brachial plexus in 37%.

Dorsal scapular artery from third part 58.5% runs between the trunks of brachial plexus.

When Dorsal scapular artery runs above trunks of brachial plexus it cause compression of cords resulting in intermittent neurological radiating pain when the patient raises his hand is observed by the study done by Anne Marie.82

106 CHAPTER - VII

SUMMARY & CONCLUSION

107 SUMMARY AND CONCLUSIONS

The branching pattern of subclavian artery has been studied and the observed results lead to the following conclusions.

1) The five branches of subclavian artery 37/60 arteries (63%), four

branching pattern is seen in 21/60(35%), three branching pattern is seen

2/60 (3.3%) arteries.

2) The vertebral artery origin from subclavian artery is seen in 59/69 (97%)

arteries. Vertebral artery from arch of aorta is seen in 1/60 arteries

(3%).

3) The prevertebral segment of vertebral artery is the range of 3.5 to 3.9 cm,

but one artery was observed to be lengthier of 8.8cm.

4) The vertebral arteries 59/60 entered at the level of C6 foramen

Transversorium, but one vertebral artery which is lengthier entered the

foramen transversorium at the level of C4.

5) Internal thoracic artery origin from first part of Subclavian artery is seen

in 59/60 Arteries. One internal thoracic artery have common origin

with Thyrocervical trunk. (3%).

6) In the branching pattern of Thyrocervical trunk, Two branching pattern

is seen in 10/60(16.6%).Three branching pattern was seen in 45/60

(75%) arteries. Four Branching pattern was seen in 3/60 (5%) arteries,

108 five branching pattern of Thyrocervical trunk is seen in 1/60 (3%).In one

subclavian arteries Thyrocervical Trunk is absent. (3%)

7) Inferior thyroid artery originating from subclavian artery is seen in 59/60

Arteries (97%). One inferior thyroid artery arises directly from

subclavian artery.

8) The Recurrent laryngeal nerve is superior to Inferior thyroid artery in

10/60 (16.5%), recurrent laryngeal nerve deep to Inferior thyroid artery in

28/60 (14%), between the branches of Inferior thyroid artery in 22/60

(39.1%).

9) Transverse cervical artery a branch of Thyrocervical trunk is present in

49/60 arteries (81.5%).In 11/60 subclavian arteries transverse cervical

artery is absent (18.5%).

10) Origin of Suprascapular artery from first part of Subclavian artery in

39/60(65%), From third part of subclavian artery in 13/60(21.6%), from

axillary artery in 8/60 arteries (13.3%).

11) Deep cervical artery is present along with highest intercostal artery in a

trunk in 39/60(65%).Among 39 Deep cervical artery, two deep cervical

artery (3.3%) with Dorsal scapular artery as a trunk. Deep cervical

artery as a direct branch in 11 subclavian arteries (18.3%). Deep cervical

artery is absent in 10/60 (16.6%).

109 12) In 80% of subclavian arteries third part has branches either Dorsal

scapular artery or suprascapular artery. In 20% third part doesn’t have

arteries.

13) Dorsal scapular artery from Thyrocervical trunk in 20/60 arteries

(35.3%). Dorsal Scapular artery along with deep cervical artery from a

common trunk in two artery (3.3%).Dorsal scapular artery from third part

of Subclavian artery in 35/60(58.3%).

14) The Dorsal scapular artery was running above brachial plexus in 21/60

(35%), Dorsal scapular artery running between or below the trunks of

brachial plexus in 39/60 arteries, one Dorsal scapular artery from a trunk

with Deep cervical artery is not Closely related to brachial plexus.

SIGNIFICANCE OF THE STUDY:

In the current study all the subclavian arteries are having normal origin and termination. Anatomical knowledge of origin, branching pattern and termination will be helpful for the surgeons.

Anomalous origin of vertebral artery is potential pitfall at diagnostic cerebrovascular imaging. Vertebral arteries are may be assumed to be occluded or missing in Doppler sonography, CT angiography. The knowledge of variations of vertebral artery will be helpful for the physicians and surgeons to avoid damage to vertebral artery during any procedures.

110 It is obvious that Internal thoracic artery from Thyrocervical trunk may complicate surgical grafting procedure. Internal thoracic artery is great conduit for myocardial revascularisation and its variations in origin will be helpful for cardiothoracic surgeons.

Thyrocervical trunk is present in all subclavian arteries except one on the left. As inferior thyroid artery is one of the important source of blood supply to the thyroid gland and related to recurrent laryngeal nerve .so variations in origin of inferior thyroid artery will be helpful to surgeons.

Orthopaedic surgeons while removing cervical rib care should be taken to avoid damage to subclavian artery and its branches like transverse cervical artery.

Plastic surgeons while doing head and neck reconstructive surgeries they have to take trapezius musculo cutaneous flap which is supplied by Dorsal scapular artery.

The normal suprascapular artery is from thyrocervical trunk, but in this study from third part and also from axillary artery is reported.

Any clavicular fracture will cause damage to suprascapular artery of anomalous origin.

Surgeries in the anterior neck and supraclavicular regions such as radical and modified neck dissections in controlling lymphogenous spread of head and

111 neck cancer, may require ligation of suprascapular artery. So thorough knowledge of variations of suprascapular artery will be helpful for orthopaedicians and surgeons.

During any vascular surgery of triangle region of the neck, these anatomical variations must be taken into account in order to limit circulatory complications.

In this study subclavian artery showed variations in its branches, comparison and analysis of results with previous literature showed that subclavian artery has variations subject to its branches. This information will aid anatomists, vascular surgeons and Head and neck surgeons.

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127

ANNEXURES

S. No. CONTENTS

1. PLAGIARISM ANALYSIS REPORT

2. PLAGIARISM SCREEN SHOT REPORT

3. DR.MGR MEDICAL UNIVERSITY PLAGIARISM VERIFIED GUIDE CERTIFICATE

4. INSTITUTIONAL ETHICAL COMMITTEE APPROVAL CERTIFICATE

5. ABBREVIATIONS

128

129

130 PLAGIARISM CERTIFICATE

This is to certify that this dissertation work titled “ANATOMICAL

ANALYSIS OF ORIGIN , BRANCHING PATTERN AND VARIATIONS

OF SUBCLAVIAN ARTERIES IN HUMAN CADAVERS” of the candidate

Dr.T.N.Pavazhakkurinji with Registration Number 201733351 for the award of

M.D. in the branch of ANATOMY. I personally verified the urkund.com website for the purpose of plagiarism check. I found that the uploaded thesis file contains from Introduction to conclusion pages and result shows 4% of

Plagiarism in the dissertation.

Guide and Supervisor sign with Seal

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ABBREVATIONS

SCA - subclavian artery

BCT - Brachiocephalic trunk

AOA - Arch of aorta

VA - Vertebral artery

ITA - Inferior thyroid artery

TCT - Thyrocervical trunk

TCA - Transverse cervical artery

SSA - Suprascapular artery

DSA - Dorsal scapular artery

RLN - Recurrent laryngeal nerve

CCT - Costocervical trunk

DCA - Deep cervical artery

Rltn - Relation

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