Axilla & Brachial Plexus PDF - Gulf Medical University

Axilla & Brachial Plexus October 6, 2024 www.gmu.ac.ae I. The axilla: − Is the gateway to the upper limb, providing an area of transition between the neck and the arm. − It is pyramidal in shape. − It has 4 walls, inlet and base. 1. The axillary inlet (...

Axilla & Brachial Plexus October 6, 2024 www.gmu.ac.ae I. The axilla: − Is the gateway to the upper limb, providing an area of transition between the neck and the arm. − It is pyramidal in shape. − It has 4 walls, inlet and base. 1. The axillary inlet (apex): – Is continuous superiorly with the neck. Boundaries: It’s anteriorly formed of clavicle, Posteriorly scapula and Medially the first rib. 2. The floor (base): − It is formed of skin of arm pit. II. Contents Of Axilla: 1. Brachial plexus. 2. Axillary artery. 3. Axillary vein. 4. Axillary lymph nodes. 5. Tail of the breast in females. 10/6/2024 5 1. Brachial plexus: 1. The brachial plexus is formed by the anterior rami of C5 ,C 6,C7,C8, and most of the anterior ramus of T1. 2. It originates in the neck, passes laterally and inferiorly over rib 1, and enters the axilla. 3. It has 5 stages, it started with roots , trunks in the neck, then divisions behind the clavicle, cords in the axilla and finally terminal branches.  C5 A. Division U. Trunk C5,6 L. Cord, C5,6,7 C6 A. Division P. Cord,C5,6,7,8,T1 C7 M. Trunk C7 P. Division C8 M. Cord, C8,T1 A. Division L. Trunk C8,T1 T1 Ventral rami of spinal nerves = Roots of the plexus A. Roots : 5 − The roots of the brachial plexus are the anterior rami of C5 to C8, and most of T1. B. Trunks: 3 – The 3 trunks of the brachial plexus originate from the roots, pass laterally over rib 1, and enter the axilla. The superior trunk is formed by the union of C5 and C6 roots. The middle trunk is a continuation of the C7 root. The inferior trunk is formed by the union of the C8 and T1 roots C. Divisions: 6 − Each of the 3 trunks of the brachial plexus divides into an anterior and a posterior division. − The 3 anterior divisions form parts of the brachial plexus that give rise to nerves of the anterior compartments of the arm and forearm. − The 3 posterior divisions combine to form parts of the brachial plexus that give rise to nerves of the posterior compartments. D. Cords : 3 – The 3 cords of the brachial plexus originate from the divisions and are related to the second part of the artery axillary. 1. The lateral cord results from the union of the anterior divisions of the upper and middle trunks and therefore has contributions from C5 to C7. It is positioned lateral to the second part of the axillary artery. 2. The medial cord is continuation of the anterior division of the inferior trunk and therefore has contributions from C8 and T1. It is positioned medial to the second part of the axillary artery. 3. The posterior cord is the union of all 3 posterior divisions; therefore has contributions from all roots of the brachial plexus. It is positioned posterior to the second part of the axillary artery. Branches from the roots: 1. Long thoracic nerve (nerve to serratus anterior) (C5,6,7). 2. Dorsal scapular nerve (nerve to rhomboids) (C5). 3. Rootlets of the phrenic nerve (C5). Branches from the upper trunk (2S): 1. Suprascapular nerve (C5,6). 2. Nerve to subclavius (C5,6). Branches of the lateral cord (3): LML 1. Lateral pectoral nerve (C5,6,7). 2. Musclo -cutaneous nerve (C5,6,7). 3. Lateral root of median nerve (C5,6,7). Branches of the medial cord : M4U : 1. Medial root of median nerve (C8,T1). 2. Medial cutaneous nerve of the forearm 3. Medial cutaneous nerve of the arm (C8,T1). 4. Medial pectoral nerve (C8,T1). 5. Ulnar nerve (C8,T1). Branches of the posterior cord : ULNAR/ULTRA 1. Upper subscapular nerve (C5,6). 2. Lower subscapular nerve (C5,6). 3. Nerve to latissimus dorsi (thoraco – dorsal) (C6,7,8) 4. Radial nerve (C5,6,7,8,T1). 5. Axillary nerve (C5,6). 2. Axillary artery: – It is the main blood supply of the upper limb. – It starts at the lateral border of the first rib as continuation of the subclavian artery. – It ends at the lower border of teres major muscle ,then becomes brachial artery. Branches: ✓ Anterior circumflex humeral artery passes anterior to the surgical neck of the humerus ✓ Posterior circumflex humeral artery passes posterior to the surgical neck. Axillary nerve: ▪ It originates from the posterior cord of the brachial plexus. ▪ It exits the axilla by passing through the quadrangular space & enters the posterior scapular region. ▪ Together with the posterior circumflex humeral vessels , related to the posterior surface of the surgical neck of the humerus. ▪ It innervates the deltoid and teres minor muscles. ▪ It gives superior lateral cutaneous nerve of the arm, which carries sensation from the skin over the deltoid muscle. Objectives: 1. Describe the boundaries, contents of axilla 2. Explain the formation and the branches of the brachial plexus Reference: Netter's Clinical Anatomy. Hansen, John T. Elsevier; 2019 4th Edition. ISBN: 978-0-323- 53188-7 https://www.clinicalkey.com/#!/content/bo ok/3-s2.0-B978032353188700007X Pectoral region Dr. Sapna Shevade Assistant Professor of Anatomy October 6, 2024 www.gmu.ac.ae Serratus Anterior Winging of scapula : Caused by paralysis of serratus anterior muscle Scapular region October 6, 2024 www.gmu.ac.ae Muscles of the scapular region 1. Supraspinatus 2. Infraspinatus 3. Teres minor 4. Teres major Muscles of the scapular region 1. Subscapularis  Deltoid Spaces of scapular region Posterior quadrangular space Superiorly: teres minor Inferiorly: teres major Laterally: humerus. Medially: long head of triceps brachii Contents: Axillary nerve Posterior circumflex humeral vessels The upper triangular space Superiorly: teres minor. Inferiorly: teres major. Laterally: long head of triceps brachii. Contents : circumflex scapular vessels The lower triangular interval Medially: long head of triceps brachii. Laterally: the shaft of the humerus. Superiorly: teres major. Contents: radial nerve, the profunda brachii artery Contents  Back muscles Dr. Sapna Shevade Assistant Professor of Anatomy October 6, 2024 www.gmu.ac.ae  Superficial muscles of the back Trapezius From medial border of scapula Levator scapulae : Nerve supply: Rhomboidus major: Rhomboidus minor: Latissimus dorsi Action: extends & rotates the humerus medially Powerful adductor Climbing,swimming