The Cubital Fossa

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Original Author(s): Oliver Jones
Last updated: November 8, 2020
Revisions: 44

Original Author(s): Oliver Jones
Last updated: November 8, 2020
Revisions: 44

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The cubital (anticubital) fossa is a triangular-shaped depression over the anterior aspect 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.

In this article, we shall look at the anatomy of the cubital fossa – its borders, contents and clinical relevance.

Fig 1 – The cubital fossa is a triangular-shaped depression over the anterior aspect of the elbow.

Borders

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).

Fig 2 – The medial and lateral borders of the cubital fossa are formed by the muscles of the anterior forearm.

Contents

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

Its contents are (lateral to medial):

  • Radial nerve – travels along the lateral border of the cubital fossa and divides into superficial and deep branches.
    • It has a motor and sensory function in the posterior forearm and hand.
  • Biceps tendon – passes centrally through the cubital fossa and attaches the radial tuberosity (immediately distal to the radial neck).
    • It gives rise to the bicipital aponeurosis which contributes to the roof of the cubital fossa.
  • 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
  • Median nerve travels medially through the cubital fossa, exiting by passing between the two heads of the pronator teres.
    • It has a motor and 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 accessed easily –  a common site for venepuncture.

Mnemonic for contents of the cubital fossa – Really Need (radial nerve) Beer To (biceps tendon) Be At (brachial artery) My Nicest (median nerve).

Fig 3 – Contents of the cubital fossa

Clinical Relevance: Supracondylar Fracture

supracondylar fracture 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 repaired, can cause Volkmann’s 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:

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

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

Fig 1.7 - A supracondylar fracture of the humerus

Fig 4 – A supracondylar fracture of the humerus