Axilla Flashcards
What are the borders?
Apex – Also known as the axillary inlet, this is formed by lateral border of the first rib, superior border of scapula, and the posterior border of the clavicle.
Lateral wall – Formed by intertubercular groove of the humerus.
Medial wall – Consists of the serratus anterior and the thoracic wall (ribs and intercostal muscles).
Anterior wall – Contains the pectoralis major and the underlying pectoralis minor and the subclavius muscles.
Posterior wall – Formed by the subscapularis, teres major and latissimus dorsi.
What are the contents?
Axillary artery – It is the main artery supplying the upper limb. It is commonly referred as having three parts, one medial to the pectoralis minor, one posterior to pectoralis minor, and one lateral to pectoralis minor. The medial and posterior parts travel in the axilla.
Axillary vein – The main vein draining the upper limb, its two largest tributaries are the cephalic and basilic veins.
Brachial plexus – A collection of spinal nerves that form the peripheral nerves of the upper limb.
Biceps brachii and coracobrachialis – These muscle tendons move through the axilla, where they attach to the coracoid process of the scapula.
Axillary Lymph nodes – The axillary lymph nodes filter lymph that has drained from the upper limb and pectoral region. In women, axillary lymph node enlargement is a non-specific indicator of breast cancer.
What are the routes of exit?
The main route of exit is immediately inferiorly and laterally, into the upper limb. The majority of contents of the axilla region leave by this method.
Another pathway is via the quadrangular space. This is a gap in the posterior wall of the axilla, allowing access to the posterior arm and shoulder area. Structures passing through include the axillary nerve and posterior circumflex humeral artery (a branch of the axillary artery.
The last passageway is the clavipectoral triangle, which is an opening in the anterior wall of the axilla. It is bounded by the pectoralis major, deltoid, and clavicle. The cephalic vein enters the axilla via this triangle, while the medial and lateral pectoral nerves leave.
