Cubital Fossa
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Direct answer
The cubital fossa is a triangular intermuscular depression in front of the elbow. Its base is an imaginary line joining the two epicondyles of the humerus, its medial boundary is the lateral border of pronator teres and its lateral boundary is the medial border of brachioradialis. From medial to lateral it contains the median nerve, the brachial artery with its terminal branches, the biceps tendon and the lateral cutaneous nerve of the forearm.
What you must remember
- Boundaries: base — interepicondylar line; medial — lateral border of pronator teres; lateral — medial border of brachioradialis; the apex is where these two muscles meet.
- Floor: brachialis medially and supinator laterally; the capsule and radial collateral ligament of the elbow joint lie deep to them.
- Roof: deep fascia of the forearm, reinforced by the bicipital aponeurosis; superficial to the roof run the median cubital vein and the medial and lateral cutaneous nerves of the forearm.
- Contents, medial to lateral: median nerve, brachial artery (dividing into radial and ulnar arteries at the level of the radial neck), biceps tendon, and the lateral cutaneous nerve of the forearm — the terminal branch of the musculocutaneous nerve.
- Radial nerve: not a formal content — it lies deep in the lateral part, in the gutter between brachialis and brachioradialis, dividing into superficial and deep branches.
- Supratrochlear lymph nodes lie in the medial part of the fossa and drain the medial two fingers, ulnar forearm and hand.
- Clinical: the median cubital vein is the favourite venepuncture site because the bicipital aponeurosis separates it from the brachial artery; supracondylar fracture of the humerus can lacerate the brachial artery, leading to Volkmann's ischaemic contracture.
Common confusion
The recurring error is reversing the medial-to-lateral order — median nerve is most medial and the biceps tendon sits in the middle of the fossa, not the artery. Students also wrongly place the radial nerve among the contents; it remains outside, between brachioradialis and brachialis. Another trap is confusing the lateral cutaneous nerve of the forearm (musculocutaneous, sensory) with the median nerve, which gives no branches in the arm and passes medial to the biceps tendon on its way to between the two heads of pronator teres.
Exam-focused takeaway
In theory, draw the triangle, list boundaries, floor, roof and contents in the correct order, and mention the bicipital aponeurosis and brachial artery relations. In viva, be prepared for why blood is taken from the median cubital vein, and the consequences of supracondylar fracture — brachial artery injury, median nerve injury and Volkmann's contracture. In practicals and spotters, identify the biceps tendon and trace the brachial artery and median nerve on a prosection; locate the supratrochlear nodes in the medial corner.
Frequently asked questions
What are the boundaries of the cubital fossa?
Base — line joining the medial and lateral epicondyles of the humerus; medial — lateral border of pronator teres; lateral — medial border of brachioradialis. Floor — brachialis and supinator; roof — deep fascia with the bicipital aponeurosis.
What is the order of the contents from medial to lateral?
Median nerve, brachial artery with its terminal branches, biceps tendon and the lateral cutaneous nerve of the forearm.
Why is the median cubital vein preferred for venepuncture?
It is superficial, visible and tethered, and the bicipital aponeurosis beneath it separates it from the brachial artery and median nerve. This reduces the risk of arterial puncture or nerve injury.
What is the fate of the brachial artery in the fossa?
It runs medial to the biceps tendon and divides at the level of the neck of the radius into the radial and ulnar arteries. It is endangered in supracondylar fractures of the humerus.