Cubital fossa contents from lateral to medial
The cubital fossa, a triangular hollow in front of the elbow, has these main contents from lateral to medial: radial nerve, biceps tendon, brachial artery, median nerve.
Remember
The main contents run from the radial nerve laterally to the median nerve medially, so the median nerve is the most medial of the four, with the brachial artery just medial to the biceps tendon.
Mnemonic
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- R Radial
- N nerve
- B Biceps
- T tendon
- B Brachial
- A artery
- M Median
- N nerve
Use the phrase to recall the order of the structures from lateral to medial.
The cubital fossa is a small triangular hollow in front of the elbow. Its lateral border (the thumb side, with the palm facing forwards) is brachioradialis, a forearm muscle, and its medial border (the little-finger side) is pronator teres, a forearm muscle that turns the palm downwards.
The main contents run from lateral to medial: the radial nerve, the biceps tendon, the brachial artery and the median nerve. The radial nerve travels along the lateral border of the fossa, and the median nerve is the most medial of the four.
The order matters in practice. The brachial artery lies just medial to the biceps tendon, so its pulse is felt by pressing there, which helps when taking blood pressure or checking peripheral pulses (pulses in the limbs). The median nerve lies immediately medial to the artery.
A needle placed on the lateral side of the fossa can irritate the radial nerve or its branches. That can cause paraesthesia (an abnormal tingling or pins-and-needles sensation) in the skin of the back of the hand and the back of the thumb.
The veins used for venepuncture (taking blood) are separate from these deep contents. The median cubital vein runs in the roof of the fossa, in the fat layer under the skin. The ulnar nerve is also not a content of the fossa, because it passes behind the medial epicondyle (the bony bump on the inner side of the elbow).
Key facts
- Order
- from lateral to medial, the main contents are the radial nerve, biceps tendon, brachial artery and median nerve.
- Most medial
- the median nerve is the most medial of the four main contents.
- Brachial pulse
- it is felt just medial to the biceps tendon, which is useful when taking blood pressure or checking peripheral pulses.
- Median cubital vein
- it lies in the superficial tissue of the roof and is not one of the deep contents.
- Ulnar nerve
- it passes behind the medial epicondyle and is not a content of the fossa.
- Radial nerve
- it lies along the lateral border of the fossa, and its superficial branch supplies the skin of the back of the hand and the lateral three and a half digits (the thumb and fingers), including the back of the thumb.
Exam traps
- The radial nerve is a well-known nerve at the elbow, but it is not the most medial content of the cubital fossa: it travels along the lateral border, so it is the most lateral content.
- The median nerve is not the structure immediately medial to the biceps tendon, because the brachial artery lies between them and the median nerve lies medial to the artery.
- Tingling in the back of the thumb after venepuncture does not point to the median nerve, because that nerve lies on the medial side of the fossa and mainly supplies the palm side of the thumb rather than the back of it.
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