Flexor digitorum profundus
The flexor digitorum profundus helps flex the fingers. The muscle originates in the upper part of the ulna bone and stretches to insertion at the distal phalanges in the tips of the fingers. Yet, the physical look of the muscle can be deceiving. The muscle's belly appears on the forearm, but since the muscle provides mostly for hand functionality, it is considered a hand muscle. This notion is further reinforced by the muscle's long tendons, which extend over the wrist and the metacarpals of the hand. Along with the flexor digtorum profundus, the flexor pollicis longus and the pronator quadratus fill out the forearm. For oxygentated blood, the flexor digitorum profundus muscle relies on the anterior interosseous artery. As for a connection to the brain, the muscle is innervated by the anterior interosseous and the ulnar nerves. If either the nerves or the muscle itself suffers damage, the fingers would lose their dexterity. Also, a person would not be able to flex their fingers, as the extensor digitorum muscles would work unopposed.
Written and medically reviewed by the Healthline Editorial Team
In Depth: Flexor digitorum profundus