Areas - Cubital Fossa

Question 1

What is the cubital fossa?

Answer 1

It is a triangular-shaped depression over the anterior aspectr of the elbow joint.

It represents an area of transition between the anatomical arm and the forearm, and conveys several important structures between these two areas.

Question 2

Borders?

Answer 2

The cubital fossa is triangular in shape and consists of three borders, a roof and a floor:

Lateral border - medial border of the brachioradialis muscle.

Medial border - lateral border of the pronator teres muscle.

Superior border - horizontal line drawn between the epicondyles of the humerus.

Roof - bicipital aponeurosis, fascia, subcutaneous fat and skin.

Floor - brachialis (proximally) and supinator (distally)

Question 3

Contents?

Answer 3

The cubital fossa is a passageway for structures to pass between the upper arm and forearm.

Its contents are (lateral to medial:

1) Radial nerve - travels along the lateral border of the cubital fossa and divides into superficial and deep branches.
- It has motor and sensory function in the posterior forearm and hand.
2) Biceps tendon - passes centrally through the cubital fossa and attaches to the radial tuberosity (immediatly distal to the radial neck).
- It gives rise to the bicipital aponeurosis which contribues to the roof of the cubital fossa.
3) Brachial artery - bifurcates into the radial and ulnar arteries at the apex of the cubital fossa.
- The brachial pulse can be felt in the cubital fossa by palpating medial to the biceps tendon.
4) Median nerve - travels medially through the cubital fossa, exiting by passing between the two heads of the pronator teres.
- It has a motor and a sensory function in the anterior forearm and hand.

The roof of the cubital fossa also contains several superficial veins. Notably, the median cubital vein, which connects the basilic and cephalic veins and can be easily accessed - a common site for venepuncture.

Mnemonic:
Really Need (radial nerve)

Beer To (biceps tendon)

Be At (brachial artery)

My Nicest (median nerve)

Question 4

Clinical relevance - supracondylar fracture?

Answer 4

This is a fracture of the distal humerus. The fracture is typically transverse or oblique, and the most common mechanism of injury is falling on an outstretched hand. It is more common in children than adults.

In this type of injury, the contents of the cubital fossa can be damaged - either directly, or by soft tissue swelling following the trauma. Damage to the brachial artery, if not reparied, can cause Volkmanns ischaemic contracture (uncontrolled flexion of the hand) as the forearm flexor muscles become fibrotic and short.

There also can be damage to the anterior interosseous nerve (branch of the median nerve), ulnar nerve or radial nerve. The anterior interosseous nerve can be tested by asking the patient to make an ‘OK’ sign, testing for weakness of flexor pollicis longus.

The Gartland classification is used for these fractures:

1) Type 1 is minimally displaced
2) Type 2 is displaced with but an intact posterior cortex
3) Type 3 is completely off-ended

Type 1 can be managed conservatively with an above elbow case whereas types 2 and 3 typically require surgical fixation with crossed, bi-cortical k-wires.