Pectoral Region and Axilla

Musculoskeletal block- Anatomy-lecture 5

Editing file Color guide : Objectives Only in boys slides in Blue Only in girls slides in Purple important in Red ✓ By the end of the lecture the students should be able to : Doctor note in Green ✓ Identify and describe the muscles of the pectoral region. Extra information in Grey I. . II. . III. Subclavius. IV. Serratus anterior. ✓ Describe and demonstrate the boundaries and contents of the axilla. ✓ Describe the formation of the brachial plexus and its branches. Type of muscle Origin Insertion Nerve Supply Action Picture

2 heads Lateral lip of Medial & lateral -Adduction and Clavicular head: From bicipital groove pectoral nerves. medial rotation of Medial ½ (humerus) the arm.

of the front of the . -clavicular head helps in flexion of Sternocostal head: From; arm (shoulder) Pectoralis Sternum Upper 6 costal -Also help in Major cartilages. climbing Aponeurosis of the external oblique muscle

-Depression of the shoulder. Pectoralis -Draw the ribs upward and Minor rd th th From 3 ,4 , & 5 ribs close Medial pectoral outwards during

Deep to to their costal cartilages (scapula) nerve. deep inspiration. pectoralis major Type of muscles Origin Insertion Nerve Supply Action Picture

From 1st rib and its Subclavian groove in Nerve to Fixes the clavicle costal cartilage( the 1st the middle 1/3 of the subclavius from during movement of Subclavius costochondral junction) inferior surface of upper trunk of shoulder joint. clavicle. brachial plexus

Upper eight ribs. anterior aspect of the Long thoracic -Draws the scapula medial border and nerve (nerve to forward in boxing, inferior angle of serratus (protrusion or scapula anterior). protraction). "boxer's Serratus muscle" anterior -Rotates scapula outwards in raising the arm above 90 degree (Abduction above 90) with . Clavipectoral ➢ It is thickened membrane of deep fascia between subclavius and & pectoralis minor below). ➢ It is pierced by : 1- . 2- . 3- Cephalic vein. 4- lymph vessels. Axilla

A 4 sided pyramid-shaped space between the upper part of the arm and the side of the chest It’s the space through which major neurovascular structures pass between neck & and upper limbs. The Axilla has: 1.-Apex 2-Base 3- Four Walls: Anterior, Posterior, Medial ,Lateral walls

Apex Base (floor)

It's called Cervicoaxillary canal formed by skin stretching between the anterior and posterior walls. It is directed upwards and medially into the root of the The base is bounded: neck. 1- In front by the anterior axillary fold (formed by the lower border of The Apex is bounded by 3 bones: the Pectoralis major). 2- Behind by the posterior axillary 1- Clavicle anteriorly. fold (formed by the tendons of 2- Upper border of the scapula latissimus dorsi and teres major posteriorly muscles). 3- Outer border of the first rib 3- Medially by upper 4 or 5 ribs and medially. the chest wall. Anterior wall Boundaries of axilla

Four wall Lateral wall Medial wall

Anterior Posterior Medial Lateral it is formed by: It is formed by: It is formed by: It is formed by: Posterior wall 1) Pectoralis major 1) Subscapularis 1) Serratus 1)Coracobrachialis 2) Pectoralis minor 2) Latissimus anterior 2) Biceps brachii 3) Subclavius dorsi 2) Upper 4-5 ribs 3) intertubercular 4) Clavipectoral 3) Teres major and intercostal groove of the fascia muscles muscle humerus Contents of The Axilla

❖ Cords and branches of brachial plexus ❖ and its branches ❖ and its tributaries ❖ Axillary lymph nodes ❖ Axillary fat ❖ Loose connective tissue

➢ The neurovascular bundle is enclosed in loose connective tissue sheath, called axillary sheath Brachial Plexus Brachial Plexus

Location & Formation:

It is present in the is a network of nerves that posterior triangle of the present at the root of the neck & axilla. neck to enter the upper limb. It is formed by the union of the anterior Rami of the C 5th, 6th, 7th, 8th, T 1st spinal nerve.

• The first 2 stages lie in the posterior triangle, while the last 2 sages lie in the axilla. Remember in the spine we only have 7 cervical vertebra BUT there are 8 cervical spinal nerves. Brachial Plexus

Roots and trunk Division and cords

Roots of C5 & C6 unite to form Superior trunk The anterior divisions of the upper and middle trunks unite to form the Lateral cord. Roots of C7 continues as the Middle trunk -The anterior division of the lower trunk continues as the Roots of C8 & T1 unite to form Inferior trunk Medial cord.

-All the posterior divisions of three trunks join to form the Each trunk will branch into anterior and posterior division Posterior cord. Cords are named according to their relation to the 2nd part of the axillary artery. Summary from our reference Brachial Plexus

Branches

From Cords From From Roots Trunks Lateral cord (3) Medial Cord (5) Posterior Cord (5)

Dorsal Suprascap 1-Lateral pectoral 1-Medial pectoral nerve 1-. scapular ular nerve nerve 2-Ulnar nerve 2-Radial nerve nerve (C5) (C5,C6) 2-Musculocutaneous 3-Median nerve (medial 3-Upper subscapular Long thoracic Nerve to nerve root) nerve nerve (C5,6,7) subclavius 3-Median nerve 4-Medial cutaneous 4-lower-subscapular muscle (lateral root). nerve of arm nerves (C5,C6) 5- Medial cutaneous 5-Thoracodorsal or N. nerve of arm forearm to latissimus dorsi

Mnemonic (Team 433) - Lateral Cord Branches: LLM "Lucy Loves Me“ Lateral pectoral, Lateral root of the median nerve, Musculocutaneous. -Medial Cord Branches: MMUM "Most Men Use Morphine“ Medial pectoral, Medial cutaneous nerve of arm and forearm, Ulnar, Medial root of the median nerve. - Posterior cord branches STAR Subscapular (upper and lower), Thoracodorsal, Axillary, Radial Applied Anatomy

● Lesion of long thoracic nerve (C5,6,7) causes backward projection of medial border of scapula This deformity is called Winging of Scapula.

● Caused Paralysis in MCQs Question 5: Which wall is formed (partly) by the clavipectoral Question 1: Which of the following statements is NOT correct: fasica? A- The base of axilla is bounded posteriorly by the pectoralis A- Anterior major. B- Posterior B- The base of axilla is bounded medially by the 4 or 5th rib. C- Medial C- The apex of the axilla is bounded by 3 bones (clavicle, D- Lateral scapula and the 1st rib). D- The apex is called cervicoaxillary canal Question 6: In the brachial plexus all the posterior divisions of the three trunks join to form ______. Question 2: The lateral wall of the axilla does not contain: A- Lateral cord A- biceps brachii B- Posterior cord C- Lateral root B- upper 4-5 ribs and D- Posterior root C- bicipital groove of the humerus D- coracobrachialis Question 7: Which cord gives rise to the musculocutaneous nerve? A- Anterior cord Question 3: Which of the following is located between subclavius B- Posterior cord and pectoralis minor? C- Medial cord D- Lateral cord A- Serratus anterior

B- Axilla Question 8: A patient presents to the ER with inability to depress C- Clavipectoral Fascia D- Brachial Plexus his shoulders. The physician suspects nerve involvement ,which nerve is most likely damaged? Question 4: What is the nerve supply of Serratus anterior? A- Medial pectoral nerve A- Lateral pectoral nerve. B- Lateral pectoral nerve B- Long thoracic nerve. C- Anterior pectoral nerve C- Musculocutaneous nerve. D- Posterior pectoral nerve D- Ulnar nerve. Answers: Q1.A- Q2.B -Q3.C -Q4.B- Q5.A- Q6.B-Q7.D- Q8.R Team members

Girls team : Boys team:

● Ajeed Al Rashoud ● Khalid AL-Dossari ● Taif Alotaibi ● Naif Al-Dossari ● Noura Al Turki ● Faisal Alqifari ● Amirah Al-Zahrani ● Salman Alagla ● Alhanouf Al-haluli Special thank for ● Ziyad Al-jofan ● Sara Al-Abdulkarem ● Suhail Basuhail ● Rawan Al Zayed Anatomy team 436 ● Ali Aldawood ● Reema Al Masoud ● Khalid Nagshabandi ● Renad Al Haqbani ● Mohammed Al-huqbani ● Nouf Al Humaidhi ● Jehad Alorainy ● Fay Al Buqami ● Khalid AlKhani ● Jude Al Khalifah ● Omar Alammari ● Nouf Al Hussaini ● Alwateen Al Balawi ● Rahaf Al Shabri ● Danah Al Halees Team leaders ● Haifa Al Waily ● Rema Al Mutawa ● Abdulrahman Shadid ● Amirah Al Dakhilallah Good luck ● Ateen Almutairi ● Maha Al Nahdi ● Renad Al Mutawa Give us your feedback: ● Ghaida Al Braithen ● Reham Yousef =This lecture done by