MSK The axilla region & cubital fossa

Question 1

Briefly describe the location of the axilla region

Answer 1

Lies underneath the glenohumeral joint, and allows structures such as vessels and nerves to enter and leave the upper limb

Question 2

What are the borders of the axilla?

Answer 2

Lateral wall - intertubecular groove of humerus
Medial wall - serrates anterior and thoracic wall
Anterior wall - pec maj+min, and subclavius muscle
Posterior wall - Subscapularis, teres maj, latissimus dorsi

Apex - the axillary inlet, formed by lateral border of 1st rib, superior border of scapula, posterior border of clavicle

Question 3

What are the routes in which structures leave the axilla?

Answer 3

Main route of exit in inferiorly and laterally into the upper limb. (majority leave by this method)

Via the quadrangular space which is a gap in the posterior wall of the axilla allowing access to posterior arm and shoulder. Axillary nerve and posterior circumflex humeral artery pass through this space

Via the clavipectoral triangle, an opening in the anterior wall of the axilla. Bounded by pec maj, deltoid and clavicle. the cephalic vein enters through this triangle and the med and lat pectoral nerves leave

Question 4

What are the contents of the axilla?

Answer 4

The axillary artery - main artery supplying upper limb. Has 3 parts: medial, posterior and lateral to pec minor. (medial and posterior travel in the axilla)

The axillary vein - main vein draining the upper limb, largest tributaries are cephalic and basilic veins

Brachial plexus - spinal nerves forming peripheral nerves of upper limb

Biceps brachii and coracobrachialis - muscle tendons move through axilla where they attach to coracoid process

Axillary lymph nodes - filter lymph from upper limb and pec region (enlargement in women indicator of breast cancer)

Question 5

In what situation would a lymph node biopsy be required and what are the potential complications?

Answer 5

Biopsies if breast cancer suspected
If cancer confirmed the nodes may be removed to prevent cancer spreading (known as axillary clearance)

The long thoracic nerve may be damaged resulting in winging of scapula (supplies serratus anterior)

Question 6

What is the name of the condition in which vessels and nerves are compressed between the bones in the apex of the axilla?

Answer 6

Thoracic outlet syndrome
Common causes: trauma e.g. fractured clavicle, repetitive movement e.g. lifting of arms
Symtoms are pain in the limb, tingling, muscle weakness, discolouration

Question 7

What are the borders of the cubital fossa, and the floor and roof?

Answer 7

Lateral border - medial border of brachioradialis
Medial border - lateral border of pronator teres
Superior border - imaginary line between epicondyles of humerus

Floor - proximally is the brachialis and distally is the supinator
Roof - skin and fascia reinforced by bicipital aponeurosis

Question 8

What are the contents of the cubital fossa?

Answer 8

Lateral to medial: (nerve sandwich)

Radial nerve-which then divides into deep and superficial
Biceps tendon-runs through and attaches to radial tuberosity
Brachial artery-bifurcates at apex of cubital fossa into radial and ulnar arteries
Median nerve-supplies flexors

Question 9

Which vein is used for venepuncture?

Answer 9

Medial cubital vein - superficial to cubital fossa

connects the cephalic and basilic veins

Question 10

What is vulnerable to damage in a supracondylar fracture of the humerus?

Answer 10

Displaced fragments may damage contents of the cubital fossa
Direct damage or post fracture swelling may interfere blood supply to forearm from the brachial artery
This can cause VOLKMANNS CONTRACTURE - flexion of hand because flexors become fibrotic and short due to ischameia
Also may be damage to radial and median nerves