Axilla Anatomy PDF

Axilla CHAPTERS I LOs: By the end of the lectures, the student should be able to: Describe the site and boundaries of the axilla. List contents of the axilla Determine the site of brachial plexus. Describe the stages of the brachial plexus Enumerate branches of brachial ple...

Axilla CHAPTERS I LOs: By the end of the lectures, the student should be able to: Describe the site and boundaries of the axilla. List contents of the axilla Determine the site of brachial plexus. Describe the stages of the brachial plexus Enumerate branches of brachial plexus AXILLA - Site: it is a pyramidal region, situated between the upper part of the side of the chest wa ll and the upper part of the medial side of the arm. - Boundaries (Figs. 53- a, b, 54): it is a four sided pyramid having an apex, a base (or floor) and four walls (anterior, posterior, lateral and medial). ! Apex {cervico-axillary canal): it is a triangular interval directed upwards and medially towards the root of the neck communicating it with the axilla and through it the axillary vessels and nerves enter the axilla from the neck. The apex is bounded by: Danie rib- Outer border of the first rib, medially. Superior border of scapula, posteriorly. first Posterior surface of the clavicle, anteriorly. ! Anterior {pectoral) wall: formed of two layers: 1. Superficial layer: is formed by pectoralis major muscle. 2. Deep layer (the axillary septum), formed from above downwards by: stapula Subclavius muscle Clavi-pectoral fascia Pectoralis minor muscle Suspensory ligament of the axilla, attached below to the axillary fascia (deep fascia in the base of axilla) Anterior fold of axilla: is the lower border of the anterior wall and is formed by the twisted lower border ofpectoralis major ! Posterior {subscapular) wall: is formed from above downwards by: Subscapularis (its lateral part) Teres major Latissimus dorsi muscle.  Axilla ! Posterior fold of axilla: is the lower border of the posterior wall and is formed by teres major and latissimus dorsi muscles.It lies at lower level than the anterior fold as the anterior wall is longer than posterior wall. ! Lateral (humeral) wall: is the narrowest wall. It is formed by: Bicipital groove of humerus Short head of biceps muscle. coracobrachialis muscles. ! Medial (costal) wall: is formed by: The upper four ribs and their corresponding intercostal muscles. The upper part of serratus anterior muscle. ! Base (floor): looks downwards and is formed by: Skin (rich in hairs, sweat and sebaceous glands). Superficial fascia. Deep (axillary) fascia: Receives the attachment of suspensory ligament of the axilla. -Contents of axilla: 1- Vessels: Axillary artery and its branches. Axillary vein and its tributaries. 2- Nerves: cords of brachial plexus and their branches, the long thoracic nerve and the intercostobrachial nerve ( lateral cutaneous branch of the 2 nct thoracic nerve). 3- Lymph Nodes: five groups of axillary lymph nodes (anterior, posterior, lateral, central and apical). 4- Special contents: Tail of mammary gland. Axillary fat and loose areolar tissue N.B. The axillary artery begins at the outer border of the first rib as the continuation of the subclavian artery and ends at the lower border of the teres major muscle (lower limit of axilla) where it becomes the brachial artery. The axillary vessels and brachial plexus run from the apex to the base along the lateral wall of axilla nearer to the anterior than the posterior wall.  Axilla Apex of axilla Cervicoaxillary canal - - - -------.... Base of axilla (A) Anterior view (a) Anterior wa ll: Is formed by Pectoralis major Pectoralis minor Subclavius Clavipectoral fascia: lis pectoralis major (b) Fig. 53a & b: Boundaries of axilla (Anterior views)  Axilla pectoralis subscapularis subclavius major clavipectoral fascia lfJ__ axillary artery pectoralis minor suspensory ligament deep fascia of armpit anterior wall posterior wall pectoralis major long thoracic nerve pectoralis minor bicipital groove of humerus serratus anterior anterior medial wall lateral wall Fig. 54: Walls of axilla