Human Anatomy - Kotsan I. Y. 2009

Muscles and fascia of the upper extremity
Anterior compartment muscles of the forearm
Second layer of the anterior compartment muscles of the forearm

The flexor digitorum superficialis Muscle (m. flexor digitorum superficialis) has two heads: humeroulnar and radial. It is located in the space between the ulnar and radial flexors of the wrist, being partially covered by them as well as by the aforementioned Muscles of the anterior forearm compartment. The humeroulnar HEAD originates from the medial epicondyle of the humerus, the forearm fascia, and the coronoid process of the ulna. The radial head arises from the proximal 2/3 of the anterior border of the radius. In the proximal third of the forearm, both heads unite into a common muscle belly, which in the middle of the forearm divides again into four parts. In the distal third of the forearm, these parts continue as tendons directed toward the second, third, fourth, and fifth digits. Essentially, this Muscle consists of four separate muscles sharing a common origin but having different insertion sites. The tendons of this muscle pass into the hand through the carpal tunnel, located beneath the flexor retinaculum, and insert—after each splits into two slips—onto the bases of the middle Phalanges of digits 2–5. Function: flexes the middle phalanges of digits 2–5 and flexes the wrist; in addition, the humeroulnar head participates in flexing the forearm at the elbow joint.

Innervation: median nerve (C_V–T_hl).