Cubital Fossa

The cubital fossa is a triangular depression located anterior to the elbow joint, representing an important zone of transition between the arm and forearm.

Boundaries

Boundary	Structure
Superior (base)	Imaginary line between the medial and lateral epicondyles of the humerus
Lateral border	Brachioradialis muscle (origin: lateral supraepicondylar ridge)
Medial border	Pronator teres muscle (origin: medial epicondyle)
Floor (bed)	Brachialis muscle (mainly) + supinator (laterally)
Roof	Superficial fascia + skin (with median cubital vein in the roof)

Contents (Lateral to Medial)

Mnemonic: T-A-N (Tendon - Artery - Nerve)

Biceps brachii tendon - easily palpable; gives off the bicipital aponeurosis medially
Brachial artery - bifurcates at the apex into the radial and ulnar arteries (though this bifurcation can occur much higher, even in the axilla)
Median nerve - lies immediately medial to the brachial artery; exits by passing between the two heads of pronator teres

Radial nerve: lies just under the lip of the brachioradialis (forming the lateral margin) - it is NOT a true content of the fossa but is closely related. It divides here into its superficial branch (continues deep to brachioradialis) and deep branch (pierces supinator to reach the posterior compartment).

Ulnar nerve: does NOT pass through the cubital fossa. It passes posterior to the medial epicondyle.

Key Structures in the Roof

Median cubital vein - crosses diagonally in the subcutaneous fascia over the roof; it is the standard site for venepuncture
Cephalic vein (lateral), basilic vein (medial), and lateral/medial cutaneous nerves of the forearm also traverse the roof

Bicipital Aponeurosis

A flat connective tissue membrane that passes from the medial side of the biceps tendon into the deep fascia of the forearm. It covers and protects the brachial artery and median nerve in the distal part of the fossa - clinically important because it separates the median cubital vein (used for venepuncture) from these deeper structures.

Diagrams

Fig. 7.77 - Gray's Anatomy for Students (Margins, Contents, Radial Nerve Position, Superficial Structures):

Cubital fossa - margins, contents, radial nerve, and superficial structures

Fig. 7.121 - Gray's Anatomy for Students (Anterior view with surface anatomy):

Cubital fossa anterior view with surface anatomy

THIEME Atlas - Deep dissection showing radial nerve, deep branch, and all neurovascular structures:

Cubital fossa deep dissection - THIEME Atlas

Clinical Significance

Application	Relevance
Venepuncture / IV cannula	Median cubital vein in the roof - most common site for blood draw
Brachial pulse / BP measurement	Brachial artery palpable here; stethoscope placed here for Korotkoff sounds
Brachial artery injury	Supracondylar fracture in children can injure the brachial artery within the fossa
Anterior interosseous nerve	Arises from the median nerve near the fossa
Drug injection track marks	Pigmented "rail-road track" scars in the cubital fossa are a forensic sign of intravenous drug use

Sources: Gray's Anatomy for Students, pp. 889-890, 944; THIEME Atlas of Anatomy - General Anatomy and Musculoskeletal System

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