Overview
In the cat it has a single belly. Its tendon of origin crosses the shoulder joint and runs in the intertubercular groove of the humerus, held by the transverse humeral retinaculum and wrapped in an extension of the joint capsule.
Origin
Supraglenoid tubercle of the scapula (tuberculum supraglenoidale).
Insertion
Radial tuberosity (tuberositas radii), on the medial side of the proximal forearm.
Action
Flexes the elbow and extends the shoulder.
Innervation
Musculocutaneous nerve (n. musculocutaneus).
Clinical relevance
- The biceps reflex tests the musculocutaneous nerve and spinal cord segments C6–C8. In the cat it is often hard to elicit, so its absence alone means little.
- In brachial plexus avulsion after a road accident, elbow flexion is lost when the cranial roots (C6–C7) are affected.