VARIATIONS in the BRANCHING PATTERN of the CORDS of the BRACHIAL PLEXUS Prashant Moolya *
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International Journal of Anatomy and Research, Int J Anat Res 2018, Vol 6(4.1):5803-10. ISSN 2321-4287 Original Research Article DOI: https://dx.doi.org/10.16965/ijar.2018.346 VARIATIONS IN THE BRANCHING PATTERN OF THE CORDS OF THE BRACHIAL PLEXUS Prashant Moolya *. * Assistant Professor, Department of Anatomy, B.K.L.Walawalkar Rural Medical College, Savarde, Maharashtra, India. ABSTRACT Introduction: Brachial plexus has been the subject of various studies as it is an important nerve plexus at the junction of neck and upper limb. For procedures like neurotisation, nerve grafting and shoulder joint surgery by anterior approach, knowledge of brachial plexus and its variation will be helpful to prevent any iatrogenic trauma to the nerves. Aim of this study was to find out about the variation in the branching pattern of the cords of brachial plexus. Methods: The present study was carried out by dissection of 120 (60 right and 60 left) upper limbs in 60 embalmed cadavers that were available in the department of Anatomy of Seth G. S. Medical College and KEM hospital Mumbai. Result: Variations were encountered in the branching pattern of lateral and posterior cord, while medial cord branches did not show any variation. Conclusion: Knowledge pertaining to the variation in the branching pattern of the cords of brachial plexus will guide the operating surgeon to prevent any iatrogenic trauma. KEY WORDS: Lateral Cord, Posterior Cord, Medial Cord. Address for Correspondence: Dr. Prashant Moolya, 217/1/2,Sumohan niwas,behind hotel Janata, budhuwarpeth, Madhavnagar, Sangli- 416406, , Maharashtra, India. Phone : 8087014123 E-Mail: [email protected]; [email protected] Access this Article online Journal Information Quick Response code International Journal of Anatomy and Research ICV for 2016 ISSN (E) 2321-4287 | ISSN (P) 2321-8967 90.30 https://www.ijmhr.org/ijar.htm DOI-Prefix: https://dx.doi.org/10.16965/ijar Article Information Received: 06 Aug 2018 Accepted: 06 Sep 2018 Peer Review: 06 Aug 2018 Published (O): 10 Oct 2018 DOI: 10.16965/ijar.2018.346 Revised: None Published (P): 10 Oct 2018 INTRODUCTION to form upper trunk at the lateral border of scalenus medius; the seventh cervical ramus Brachial plexus is the important nerve plexus at forms the middle trunk; the eight cervical and the junction of neck and upper limb hence it is first thoracic rami unite to form lower trunk widely used in different studies. Sushruta, has behind scalenus anterior. The three trunks described the function of many components of projects laterally, and behind the clavicle. Each peripheral nervous system by examining of these trunks bifurcates into anterior and different injuries. Galen has contributed by posterior divisions. The lateral cord is formed differentiating nerves from tendon and by by the union of anterior divisions of upper and reporting the successful repair of nerves by other middle trunks. The medial cord is formed by the physicians [1]. anterior division of the lower trunk, which often The most common arrangement of brachial receives a branch from the seventh cervical plexus is as follows, the fifth and sixth rami unite ramus. Posterior cord is formed by the union of Int J Anat Res 2018, 6(4.1):5803-10. ISSN 2321-4287 5803 Prashant Moolya . VARIATIONS IN THE BRANCHING PATTERN OF THE CORDS OF THE BRACHIAL PLEXUS. posterior divisions of all the three trunks [2]. The infraclavicular part of the brachial plexus For procedures like neurotisation [3], nerve graft- was dissected and exposed. The three cords of ing [3], shoulder joint surgery by anterior the brachial plexus (lateral, medial and poste- approach [4], knowledge of brachial plexus and rior) were identified. Variation in the branching any variation will be helpful to prevent any pattern of the brachial plexus was noted. The iatrogenic trauma to the nerves. Internal dissected specimens were numbered; photo- fixation of a humeral fracture by the common graphs were taken and the observations were anterior approach and during other orthopaedic tabulated and statistically analysed. and neurosurgical procedures on cervical spine RESULTS and prosthetic implant placements, knowledge of brachial plexus and its variations, is of 114 upper limbs were dissected of which 58 were utmost importance. of a right side and 56 were of the left side. A Aim: Aim of this study was to find out about the hundred limbs belonged to male cadavers and variation in the branching pattern of the cords fourteen limbs belonged to female cadavers. The of the brachial plexus. ages of cadavers, at the time of death, ranged Objectives: between 18 to 90 years. 1. To note any variation in the branching Amongst the branches given by the lateral cord pattern of the lateral cord of the brachial plexus, the lateral pectoral nerve 2. To note any variation in the branching did not show any variations. The musculocuta- pattern of the medial cord neous nerve was totally absent bilaterally in 4 limbs (2 right and 2 left) and in 5 limbs even 3. To note any variation in the branching though the musculocutaneous nerve was pattern of the posterior cord present, it was not piercing the coracobrachia- MATERIALS AND METHODS lis muscle, such variation was present bilater- ally in 2 cadavers (3 right and 2 left). Communi- cation between musculocutaneous nerve and The present study was carried out in the median nerve were noted in 23 upper limbs, in Department of Anatomy of Seth G. S. Medical one limb (right side) communication was seen College and KEM hospital Mumbai by dissec- after piercing the coracobrachialis muscle and tion of 120 (60 right and 60 left) upper limbs in remaining 22 limbs (12 right and 10 left)showed 60 embalmed cadavers that were available over communication before piercing the muscle, with a period of 2 years i.e. from 2012- 2014. All bilateral distribution in 2 cadavers. cadavers of both sexes available during the study period were included. In this study, 6 limbs Variations in the branching pattern of the (4 left and 2 right) were excluded because of posterior cord of brachial plexus were as damaged nerves and a fractured humerus. follows, the appearance of two upper subscapu- Dissection was done on the upper arm and lar nerves was seen in five upper limbs (2 right axilla as per Cunningham’s manual of practical and 3 left) with bilateral distribution in two Anatomy [5], using forceps, scalpel, and cadavers. Common trunk for USN, TN, LSN, and scissors. The skin, superficial fascia and deep AN was seen in only one right limb. Common fascia were dissected and the pectoralis major trunk for TN, LSN, and AN was seen in 7 upper and pectoralis minor muscles were cut and limbs (4 right and 3 left) with bilateral distribu- reflected. The skin over the axillary region was tion in two cadavers. Common trunk for TN and incised and the fascia was reflected to uncover LSN was seen in 3 upper limbs (1 right and 2 the axillary sheath, which surrounds the axillary left) with bilateral distribution in one cadaver. vessels and brachial plexus. The axillary vein Common trunk for LSN and AN was seen in 10 and its tributaries were identified and separated upper limbs (5 right and 5 left) with bilateral from the underlying axillary artery and brachial distribution in 2 cadavers. plexus. Then the axillary vein was cut along with Branches of medial cord did not show any the associated lymph nodes. variation pattern. Int J Anat Res 2018, 6(4.1):5803-10. ISSN 2321-4287 5804 Prashant Moolya . VARIATIONS IN THE BRANCHING PATTERN OF THE CORDS OF THE BRACHIAL PLEXUS. Fig. 1: Absence of musculocutaneous nerve Fig. 5: Common trunk of thoracodorsal nerve, lower sub- scapular nerve and axillary nerve S= Superior I= Inferior M= Medial L=Lateral Fig. 6: Common trunk for upper subscapular nerve, S= Superior I= Inferior M= Medial L=Lateral thoracodorsal nerve, lower subscapular nerve, axillary BB= Biceps brachii nerve Fig. 2: Musculocutaneous nerve not piercing coraco- brachialis muscle S= Superior I= Inferior M= Medial L=Lateral S= Superior I= Inferior M= Medial L=Lateral Fig. 7: Variation in the branches of posterior cord Fig. 3: Communicating branch of musculocutaneous showing common trunk for thoracodorsal nerve and nerve with median nerve after piercing coracobrachialis lower subscapular nerve muscle S= Superior I= Inferior M= Medial L=Lateral S= Superior I= Inferior M= Medial L=Lateral Fig. 4: Two upper subscapular nerves, axillary nerve and Fig. 8: Superior and inferior division of posterior cord lower subscapular nerve arising as a common trunk. and axillary arch muscles passing between two divisions S= Superior I= Inferior M= Medial L=Lateral Int J Anat Res 2018, 6(4.1):5803-10. ISSN 2321-4287 5805 Prashant Moolya . VARIATIONS IN THE BRANCHING PATTERN OF THE CORDS OF THE BRACHIAL PLEXUS. Table 1: Absence of musculocutaneous nerve. DISCUSSION Percentage of absence of Authors musculocutaneous nerve Absent musculocutaneous nerve: Le minor Prasad rao P.V.V.(2001) 8.33% (1990) has reported an absence of musculocu- Badawoud MH (2003) 1.90% taneous nerve and the lateral cord of brachial Beheiry EE (2004) 1.70% plexus gave muscular branches to coracobra- Arora L, Dhingra (2005) 15% chialis and biceps brachi [6]. Guttenberg et al. (2009) 3.60% Hollinshead (1982) [7] has stated that rarely the Present study 3.51% musculocutaneous nerve is not found and its Table 2: Musculocutaneous nerve not piercing various branches arise from the median nerve. coracobrachialis. The absence of musculocutaneous nerve was Authors Pecentage noted by Sud M and Sharma A (2000) [8], Le Rao H. (1955) 9.33% Minor (1990) [6], Nakata et.al (1997) [9] and Bergman R.A. (1988) 22% Gumusburn (2000) [10].