Human Anatomy
Arm and Cubital Fossa
Arm and cubital fossa anatomy for MBBS: flexor and extensor compartments, brachial artery, arm nerves and cubital fossa contents, mapped to NMC codes AN11.1 to AN11.6.
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Arm and Cubital Fossa
Arm and cubital fossa anatomy for MBBS: flexor and extensor compartments, brachial artery, arm nerves and cubital fossa contents, mapped to NMC codes AN11.1 to AN11.6.
This chapter covers the muscles, nerves and vessels of the arm and the cubital fossa where the elbow is examined and blood is drawn. It emphasises the flexor and extensor compartments, the course of the median, ulnar, radial and musculocutaneous nerves, and the contents of the cubital fossa.
High-yield: Arm and Cubital Fossa
- The arm is divided by intermuscular septa into an anterior flexor compartment and a posterior extensor compartment.
- The flexor compartment contains biceps brachii, brachialis and coracobrachialis, supplied by the musculocutaneous nerve.
- The extensor compartment contains triceps brachii, supplied by the radial nerve.
- Biceps brachii is a powerful supinator of the forearm and flexor of the elbow.
- The musculocutaneous nerve pierces coracobrachialis and continues as the lateral cutaneous nerve of the forearm.
- The radial nerve runs in the spiral groove with the profunda brachii artery and is at risk in midshaft humeral fractures.
- The brachial artery is the continuation of the axillary artery and ends by dividing into radial and ulnar arteries in the cubital fossa.
- The cubital fossa is a triangular hollow bounded by pronator teres medially and brachioradialis laterally.
- From lateral to medial the cubital fossa contains the biceps tendon, the brachial artery and the median nerve.
- The floor of the cubital fossa is formed by brachialis and supinator, and its roof carries the median cubital vein.
- The median cubital vein is the common site for venepuncture and connects the cephalic and basilic veins.
- The brachial artery is used to measure blood pressure and is palpated medial to the biceps tendon.
- The ulnar nerve leaves the anterior compartment in the arm to pass behind the medial epicondyle.
- Bicipital aponeurosis crosses the cubital fossa and protects the brachial artery and median nerve deep to it.
Contents of the cubital fossa
- **Boundaries:** Pronator teres medially, brachioradialis laterally, and an imaginary line between the epicondyles above.
- **Contents (lateral to medial):** Biceps tendon, brachial artery, median nerve. The radial nerve lies just deep at the lateral edge.
- **Roof:** Skin, fascia, median cubital vein and the bicipital aponeurosis.
- **Floor:** Brachialis and supinator muscles.
NMC competencies in this chapter
- **AN11.1:** Muscles of the front and back of the arm
- **AN11.2:** Course and relations of the brachial artery
- **AN11.3:** Median, ulnar, radial and musculocutaneous nerves in the arm
- **AN11.4:** Boundaries and contents of the cubital fossa
- **AN11.5:** Superficial veins and the median cubital vein
- **AN11.6:** Applied anatomy of the arm and cubital fossa
Frequently Asked Questions
What are the contents of the cubital fossa?
From lateral to medial the cubital fossa contains the biceps tendon, the brachial artery and the median nerve. The radial nerve lies just deep to its lateral boundary.
Why is the median cubital vein clinically important?
It lies superficially in the roof of the cubital fossa and connects the cephalic and basilic veins, making it the usual site for taking blood and giving intravenous injections.
Which nerve supplies the flexor muscles of the arm?
The musculocutaneous nerve supplies biceps brachii, brachialis and coracobrachialis in the anterior compartment, then continues as the lateral cutaneous nerve of the forearm.
How is the brachial artery used clinically?
The brachial artery is palpated medial to the biceps tendon and is the vessel over which the stethoscope is placed to measure blood pressure at the elbow.
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