Overview
It arises on the caudal surface of the proximal humerus and spirals down the brachial groove (sulcus musculi brachialis) to the cranial side of the elbow. In cattle, as in the other ungulates, it ends on the radius.
Origin
Caudal surface of the proximal humerus, distal to the head.
Insertion
Proximal end of the radius, on its medial side.
Action
Flexes the elbow.
Innervation
Musculocutaneous nerve (n. musculocutaneus).
Clinical relevance
The radial nerve accompanies this muscle in the brachial groove and crosses the lateral side of the arm. It can be injured in fractures of the humeral shaft or by compression during prolonged lateral recumbency (downer cows, surgery in lateral recumbency); the animal cannot extend the elbow, carpus or digits.