Flexor digitorum profundus is a muscle in the forearm that flexes the fingers or digits. and along with the flexor pollicis longus, pronator quadratus, and flexor digitorum profundus form the deep layer of ventral forearm muscles.
Flexor digitorum profundus originates upper 3/4 of anterior & medial surfaces of ulna, interosseous membrane and deep fascia of the forearm.Flexor digitorum profundus lies deep to flexor digitorum superficialis, but it attaches more distally.
Therefore, profundus’s tendons go through the tendons of superficialis, and end up attaching to the distal phalanx. For this reason profundus is also called the perforating muscle. The muscle fans out into four tendons (one to each of the second to fourth fingers) to the palmar base of distal phalanx.
Along with flexor digitorum superficialis, it is responsible for flexor movements of fingers.
Flexor digitorum profundus is a flexor of the wrist, midcarpal, metacarpophalangeal and interphalangeal joints.
* The medial aspect of the muscle (which flexes the 4th and 5th digit) is supplied by the ulnar nerve (C8, T1)
* The lateral aspect (which flexes the 2nd and 3rd digit) by the median nerve (via its anterior interosseous branch) (C8, T1).