Flexor digitorum profundus muscle

The flexor digitorum profundus muscle is a deep muscle of the forearm that plays a crucial role in the flexion of the fingers. It is one of the key muscles involved in the intricate movements of the hand, allowing for the flexion of the distal phalanges of the fingers.

Anatomy

Origin

The flexor digitorum profundus originates from the upper three-quarters of the anterior and medial surfaces of the ulna, as well as the interosseous membrane that lies between the ulna and the radius.

Insertion

The muscle inserts into the base of the distal phalanges of the four fingers (index, middle, ring, and little fingers). Each tendon passes through the split in the tendon of the flexor digitorum superficialis muscle to reach its insertion.

Nerve Supply

The flexor digitorum profundus is innervated by two nerves:

• The lateral half (serving the index and middle fingers) is innervated by the median nerve, specifically the anterior interosseous branch.
• The medial half (serving the ring and little fingers) is innervated by the ulnar nerve.

Blood Supply

The muscle receives its blood supply from the anterior interosseous artery, a branch of the common interosseous artery, which itself is a branch of the ulnar artery.

Function

The primary function of the flexor digitorum profundus is to flex the distal interphalangeal joints of the fingers. This action is essential for gripping and manipulating objects, as it allows the fingertips to press against surfaces. The muscle also assists in flexing the proximal interphalangeal and metacarpophalangeal joints, contributing to the overall flexion of the fingers.

Clinical Significance

Injuries or conditions affecting the flexor digitorum profundus can lead to significant impairment in hand function. For example, a laceration of the tendons can result in the inability to flex the distal phalanges, a condition known as "jersey finger." Additionally, compression or injury to the nerves supplying the muscle can lead to weakness or paralysis, affecting hand dexterity.

Also see

• Flexor digitorum superficialis muscle
• Median nerve
• Ulnar nerve
• Interosseous membrane of forearm
• Hand anatomy