Corpus: Flexor carpi ulnaris muscle

Origin

The humeral head originates medially to the palmaris longus muscle on the common tendon of the flexors at the medial epicondyle of the humerus, as well as on the antebrachial fascia. The ulnar head originates on the medial side of the olecranon and the upper 2/3 of the dorsal edge of the ulna, as well as on the common intermuscular septum with the flexor digitorum superficialis muscle. Between the two muscle heads, an arc-shaped fascial extension runs, under which the ulnar nerve and the posterior ulnar recurrent artery travel distally. It runs transversely between the olecranon and the medial epicondyle and is referred to as the tendinous arch of the flexor carpi ulnaris muscle (Osborne's ligament).

Insertion

The muscle runs along the ulna and ends in a tendon that attaches to the pisiform bone and — through extending ligaments — to the hamate bone and fifth metacarpal bone. Laterally to the tendon lie the ulnar nerve and the ulnar artery.

The innervation of the flexor carpi ulnaris muscle is provided by the ulnar nerve with fibers from the C7, C8, and Th1 segments.

As implied by the name "flexor carpi ulnaris", the muscle causes flexion (bending) of the wrist (palmar flexion) as well as ulnar abduction.