Flexor pollicis brevis muscle

Flexor pollicis brevis muscle
The muscles of the left hand. Palmar surface. (Flexor pollicis brevis visible at center right, near thumb.)
Details
Latin	musculus flexor pollicis brevis
Origin	trapezium, flexor retinaculum
Insertion	thumb, proximal phalanx
Artery	Superficial palmar arch
Nerve	Recurrent branch of the median nerve, deep branch of ulnar nerve (medial head)
Actions	Flexes the thumb at the first metacarpophalangeal joint
Antagonist	Extensor pollicis longus and brevis
Identifiers
Gray's	p.461
Dorlands /Elsevier	m_22/12549129
TA	A04.6.02.055
FMA	37378
Anatomical terms of muscle

The flexor pollicis brevis is a muscle in the hand that flexes the thumb. It is one of three thenar muscles. It has both a superficial part and a deep part.

Origin and insertion

The muscle's superficial part arises from the distal edge of the flexor retinaculum and the tubercle of the trapezium, a bone in the wrist. It passes along the radial side of the tendon of the flexor pollicis longus, and, becoming tendinous, is inserted into the radial side of the base of the proximal phalanx of the thumb; in its tendon of insertion there is a sesamoid bone.^[1]

The deeper (and medial) portion of the muscle is very small, and arises from the ulnar side of the first metacarpal bone between the oblique part of the adductor pollicis and the lateral head of the first dorsal interosseous muscle, and is inserted into the ulnar side of the base of the first phalanx with the adductor pollicis.^[1]

The deep (medial) part of the flexor brevis pollicis is sometimes described as the first palmar interosseous muscle.^[1] When this muscle is included, the total number of palmar interossei is four. Otherwise, there are only three palmar interossei.

Innervation

The flexor pollicis brevis is mostly innervated by the recurrent branch of the median nerve (C8, T1). The deep part is often innervated by the deep branch of the ulnar nerve.^[2]

Blood supply

The flexor pollicis brevis receives its blood supply from the superficial palmar branches of radial artery.^[2]

Action

The flexor pollicis brevis flexes the thumb at the metacarpophalangeal joint.

Additional images

Flexor pollicis brevis muscle  Bones of the left hand. Volar surface.  Front of the left forearm. Deep muscles.  Transverse section across the wrist and digits.  Superficial palmar nerves.  Deep palmar nerves.  Flexor pollicis brevis muscle  Flexor pollicis brevis muscle  Flexor pollicis brevis muscle  Flexor pollicis brevis muscle  Flexor pollicis brevis muscle  Flexor pollicis brevis muscle  Flexor pollicis brevis muscle  Flexor pollicis brevis muscle  Flexor pollicis brevis muscle  Flexor pollicis brevis muscle  Muscles of hand. Cross section.

References

This article incorporates text in the public domain from the 20th edition of Gray's Anatomy (1918)