Flexor pollicis longus muscle

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Musculus flexor pollicis longus

Flexor pollicis longus is a muscle of the human body that belongs to the anterior compartment of the forearm. It is one of the deep muscles, playing a crucial role in the flexion of the thumb. This article provides an overview of its structure, function, innervation, and clinical significance.

Structure

The Flexor pollicis longus originates from the anterior surface of the radius and the adjacent interosseous membrane. It runs distally in the forearm, passing through the carpal tunnel within the wrist, and inserts into the base of the distal phalanx of the thumb. This muscle is unique to humans, being specifically adapted for precision grip and fine manipulation tasks.

Function

The primary function of the Flexor pollicis longus is to flex the distal phalanx of the thumb. It plays a vital role in gripping objects and performing tasks that require fine motor skills. By flexing the thumb, it contributes to the dexterous movements necessary for writing, typing, and other precise hand functions.

Innervation

The Flexor pollicis longus is innervated by the anterior interosseous nerve, a branch of the median nerve. The anterior interosseous nerve provides the motor innervation necessary for the muscle to contract and perform its function.

Clinical Significance

Injuries or conditions affecting the Flexor pollicis longus can significantly impair hand function. Conditions such as tendonitis, carpal tunnel syndrome, or trauma to the anterior interosseous nerve can lead to weakness or loss of thumb flexion. Surgical repair or rehabilitation may be required to restore the function of this muscle in such cases.

See Also

• Thumb
• Carpal tunnel syndrome
• Median nerve
• Tendonitis