Axilla Flashcards
What is the axilla?
The name given to an area that lies underneath the glenohumeral joint, at the junction of the upper limb and thorax
What is the function of the axilla?
It’s a passageway by which structures such as vessels and nerves can enter and leave the upper limb
What is the overall 3D shape of the axilla?
Looks slightly like a pyramid
What do the borders of the axilla consist of?
Four sides, and a base with an opening at the apex
What are the walls of the axilla?
Apex Lateral wall Medial wall Anterior wall Posterior wall
What is the apex of the axilla also known as?
The axillary inlet
What forms the apex of the axilla?
The lateral border of the first rib, superior border of the scapula, and the posterior border of the clavicle
What forms the lateral wall of the axilla?
The intertubecular groove of the humerus
What forms the medial wall of the axilla?
The serratus anterior and thoracic wall (ribs and intercostal muscles)
What forms the anterior wall of the axilla?
Pectoralis major and underlying pectoralis minor and subclavius muscles
What forms the posterior wall of the axilla?
Subscapularis, teres major, latissimus dorsi
How does the size and shape of the axilla vary?
With arm abuductio
When does the size of the axilla decrease most markedly?
When the arm is fully abducted
What is true of the axilla when the arm is fully abducted?
The contents of the axilla are at most risk of injury
How many routes are there by which structures leave the axilla?
Three
What is the main route of exit from the axilla?
Immediately inferiorly and laterally, into the upper limb
What are the other routes of exit from the axilla?
Via the quadrangular space
Via the clavipectoral triangle
What is the quadrangular space?
A gap in the posterior wall of the axilla
What does the quadrangular space allow?
Access to the posterior arm and shoulder
What structures pass through the quadrangular space?
Axillary nerve
Posterior circumflex humeral artery
What is the clavipectoral triangle?
An opening in the anterior wall of the axilla
What is the clavipectoral triangle bound by?
The pectoralis major, deltoid and clavicle
What travels through the clavipectoral triangle?
The cephalic vein enters the axilla
The medial and lateral pectoral nerves leave the axilla
What are the clinically important contents of the axilla region?
Axillary artery Axillary vein
Brachial plexus
Biceps brachii and coracobrachialis tendons
Axillary lymph nodes
What is the axillary artery?
The main artery supplying the upper limb
What is the axillary artery commonly referred to having?
Three parts, one medial to the pectoralis minor, one posterior to the pectoralis minor, and one lateral to the pectoralis minor
What parts of the axillary artery travel in the axilla?
The medial and posterior parts
What is the axillary vein?
The main vein draining the upper limb
What are the axillary veins largest tributaries?
The cephalic and basilic veins
What is the brachial plexus?
A collection of spinal nerves that form peripheral nerves of the upper limb
What happens to the biceps brachii and coracobrachialis tendons when they move through the axilla?
They attach to the coracoid process of the scapula
What do the axillary lymph nodes do?
Filter lymph that has drained from the upper limb and pectoral region
What does axillary lymph node enlargement mean in women?
It is a non-specific indicator of breast cancer
What is the apex of the axilla?
An opening between the clavicle, first rib and the scapula
What can happen in the apex of the axilla?
The vessels and nerves may become compressed between the bones, called thoracic outlet syndrome
What are the common causes of TOS?
Trauma, e.g. fractured clavicle
Repetitive movements
How does TOS often present?
Pain in the affected limb, tingling, muscle weakness and discolouration
What does where the pain in TOS is felt depend on?
What nerves are affected
Why can lymph nodes be biopsied if breast cancer is suspected?
Approx. 75% of lymph from the breast drains into the axilla lymph nodes
What may happen if breast cancer is confirmed?
The axillary nodes may need to be removed to prevent the cancer spreading, a procedure called axillary clearance
What may happen during axillary clearance?
The long thoracic nerve may become damaged, resulting in winged scapula
