Flexor digitorum superficialis

The flexor digitorum superficialis (Latin: musculus flexor digitorum superficialis) is a flat and prominent muscle of the upper limb that stretches between the humerus, ulna, radius and phalanges. It is classified as a muscle of the forearm, which belongs to the anterior forearm compartment. It is the largest muscle of the group. The flexor digitorum superficialis is situated in the second layer of the anterior forearm compartment. This muscle is composed of two heads - humeroulnar and radial.

Origin

The humeroulnar head of the flexor digitorum superficialis muscle originates from the medial epicondyle of the humerus and the coronoid process of the ulna. In contrast, the radial head arises from the proximal anterior margin of the radius.

Insertion

The flexor digitorum superficialis descends and via the carpal tunnel reaches the hand, where it splits into four tendons that insert on the bases of the second to fifth middle phalanges.

Action

The flexor digitorum superficialis muscle provides the flexion of the phalanges at the second to fifth metacarpophalangeal and proximal interphalangeal joints. Also, it assists in the flexion of the wrist at the wrist joint.

Innervation

The flexor digitorum superficialis is innervated by the median nerve (C8, T1) - a branch of the brachial plexus.

Blood supply

The flexor digitorum superficialis muscle receives arterial blood supply from the branches of the median, ulnar and radial arteries. The median artery arises from the ulnar artery, while the ulnar and radial arteries are branches of the brachial artery.