Cubital fossa

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Here is a complete overview of the cubital fossa from Gray's Anatomy for Students and the Thieme Atlas of Anatomy.

Cubital Fossa

The cubital fossa (also called the antecubital fossa) is a triangular depression on the anterior aspect of the elbow joint, serving as the key transition zone between the arm and the forearm. All major neurovascular structures pass through or in close relation to it.

Shape and Borders

The fossa is triangular in shape, with:

Boundary	Structure
Base (superior)	Imaginary horizontal line connecting the medial and lateral epicondyles of the humerus
Medial border	Pronator teres (arising from the medial epicondyle)
Lateral border	Brachioradialis (arising from the lateral supraepicondylar ridge)
Apex	Where the two muscles meet distally

Roof and Floor

Roof: Skin and superficial fascia, reinforced by the bicipital aponeurosis (a flat connective tissue membrane passing from the medial side of the biceps tendon to the deep fascia of the forearm). The sharp medial margin of the bicipital aponeurosis can often be felt clinically.
Floor: Mainly the brachialis muscle proximally, and the supinator muscle distally.

Contents (Lateral to Medial: mnemonic TAN)

Structure	Notes
T - Tendon of biceps brachii	Passes to attach to the radial tuberosity
A - Brachial artery	Bifurcates into radial and ulnar arteries at the apex of the fossa
N - Median nerve	Lies just medial to the brachial artery; exits by passing between the ulnar and humeral heads of pronator teres

Additionally, the radial nerve lies just deep to the lateral lip of the brachioradialis (outside the classic "contents" but within the fossa region). Here it divides into:

Superficial branch - continues deep to brachioradialis into the forearm
Deep branch - passes between the two heads of the supinator to reach the posterior compartment

Important negative: The ulnar nerve does NOT pass through the cubital fossa. It passes posterior to the medial epicondyle in the cubital tunnel.

Diagrams from Gray's Anatomy for Students

Cubital Fossa - Margins, Contents, Radial Nerve, and Superficial structures (Fig. 7.77)

Fig. 7.77 - (A) Margins, (B) Contents, (C) Radial nerve position, (D) Superficial structures - Gray's Anatomy for Students

Deep dissection of the cubital fossa - Thieme Atlas of Anatomy

Deep dissection showing the cubital fossa - Thieme Atlas of Anatomy

Structures in the Roof (Superficial / Epifascial)

These lie in the superficial fascia above the bicipital aponeurosis:

Median cubital vein - the most important; crosses diagonally from the cephalic to basilic vein
Lateral cutaneous nerve of the forearm (terminal branch of the musculocutaneous nerve)
Medial cutaneous nerve of the forearm

Clinical Significance

Application	Details
Venipuncture / IV access	The median cubital vein in the roof is the most common site for blood draws and IV cannulation. It is protected from the brachial artery beneath by the bicipital aponeurosis.
Blood pressure measurement	The stethoscope diaphragm is placed over the cubital fossa to auscultate the brachial artery (Korotkoff sounds).
Brachial artery pulse	Palpable medial to the biceps tendon; used in BP measurement and for arterial access.
Nerve block / injury	The median nerve's position makes it vulnerable to laceration, compression, or iatrogenic injury in this region.
Dialysis fistula	The brachial artery is anastomosed to the cephalic vein at the elbow (brachiocephalic fistula) to create high-flow access for hemodialysis.
Brachial artery bifurcation	Normally occurs at the apex of the fossa, but the bifurcation can occur much higher - even in the axilla. This is important during arterial procedures.
Drug injection	Repeated injections into the cubital fossa veins (e.g., IV drug use) can cause thrombosed veins, abscesses, and pigmented "rail-road track" scars.

Sources: Gray's Anatomy for Students, p. 889-890 | Thieme Atlas of Anatomy (General Anatomy and Musculoskeletal System)

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