Humeral head of extensor carpi ulnaris
Caput humerale extensoris ulnaris carpi
This is the upper, humeral head of the ulnar wrist extensor, arising from the outer elbow and running down the back of the forearm.
At a glance
- English
- Humeral head of extensor carpi ulnaris
- Latin (TA2)
- Caput humerale extensoris ulnaris carpi
- System
- Muscle
- Region
- Upper limb
- Side
- Paired, left and right
About the humeral head of extensor carpi ulnaris
Extensor carpi ulnaris is the most medial of the superficial muscles on the back of the forearm, running along the ulna from the elbow to the little finger side of the wrist. It has two heads. The humeral head is the part that starts at the elbow and gives the muscle most of its bulk; the ulnar head joins it lower down from the back of the ulna.
The humeral head takes origin from the lateral epicondyle by the common extensor tendon that it shares with extensor digitorum and extensor digiti minimi, and some fibres come from the radial collateral ligament. It descends on the back of the forearm, where the ulnar head is added from an aponeurosis attached to the posterior border of the ulna. The combined tendon runs in a groove beside the ulnar styloid, held there by its own deep sheath and by the sixth compartment of the extensor retinaculum. It ends on a tubercle on the medial side of the base of the fifth metacarpal.
The muscle extends the wrist and adducts the hand, tilting it towards the ulna. With flexor carpi ulnaris it gives a pure ulnar tilt, and with the radial extensors a straight extension. It is an important wrist stabiliser during gripping. The nerve is the posterior interosseous nerve, and the blood comes from the posterior interosseous artery and the posterior ulnar recurrent artery.
Its tendon can slip out of its groove when the forearm is turned forcibly, giving a painful snap on the ulnar side of the wrist, a problem seen in tennis players. Tendinitis here is a common cause of ulnar-sided wrist pain.
Attachments, action and supply
- Origin
- Lateral epicondyle of the humerus by the common extensor tendon, and the radial collateral ligament.
- Insertion
- With the ulnar head, the tubercle on the medial side of the base of the fifth metacarpal.
- Action
- Extends the wrist and adducts the hand; stabilises the wrist in gripping.
- Nerve supply
- Posterior interosseous nerve (C7, C8).
- Blood supply
- Posterior interosseous artery and the posterior ulnar recurrent artery.
Anthromica
See the humeral head of extensor carpi ulnaris where it really sits, with every layer of the body around it.
- Every layer, one body. Peel from muscle to bone, nerve, vessel and organ, and turn it any way.
- English and Latin. Every structure named the way your exam names it.
- Quiz until it sticks. Short drills on the structures you keep missing.
Free to start. No card.
