The abductor pollicis brevis is a muscle in the hand that functions as an
abductor of the
thumb.
Structure
The abductor pollicis brevis is a flat, thin muscle located just under the skin. It is a
thenar muscle
The thenar eminence is the mound formed at the base of the thumb on the palm of the hand by the muscles of the thumb#Intrinsic, intrinsic group of muscles of the thumb. The skin overlying this region is the area stimulated when trying to elicit ...
, and therefore contributes to the bulk of the palm's
thenar eminence
The thenar eminence is the mound formed at the base of the thumb on the palm of the hand by the intrinsic group of muscles of the thumb. The skin overlying this region is the area stimulated when trying to elicit a palmomental reflex. The word ...
.
It originates from the
flexor retinaculum of the hand
The flexor retinaculum (transverse carpal ligament, or anterior annular ligament) is a fibrous band on the palmar side of the hand near the wrist. It arches over the carpal bones of the hands, covering them and forming the carpal tunnel.
Structur ...
, the tubercle of the
scaphoid
The scaphoid bone is one of the carpal bones of the wrist. It is situated between the hand and forearm on the thumb side of the wrist (also called the lateral or radial side). It forms the radial border of the carpal tunnel. The scaphoid bone i ...
bone, and additionally sometimes from the
tubercle of the trapezium.
Running lateralward and downward, it is inserted by a thin, flat
tendon
A tendon or sinew is a tough, high-tensile-strength band of dense fibrous connective tissue that connects muscle to bone. It is able to transmit the mechanical forces of muscle contraction to the skeletal system without sacrificing its ability ...
into the lateral side of the base of the
first phalanx of the
thumb, and the
capsule of the
metacarpophalangeal joint
The metacarpophalangeal joints (MCP) are situated between the metacarpal bones and the proximal phalanges of the fingers. These joints are of the condyloid kind, formed by the reception of the rounded heads of the metacarpal bones into shallow ca ...
.
Nerve supply
The abductor pollicis brevis is supplied by the recurrent branch of the
median nerve
The median nerve is a nerve in humans and other animals in the upper limb. It is one of the five main nerves originating from the brachial plexus.
The median nerve originates from the lateral and medial cords of the brachial plexus, and has cont ...
(Roots C8-T1).
Function
Abduction of the thumb is defined as the movement of the thumb anteriorly, a direction perpendicular to the palm. The abductor pollicis brevis does this by acting across both the
carpometacarpal joint
The carpometacarpal (CMC) joints are five joints in the wrist that articulate the distal row of carpal bones and the proximal bases of the five metacarpal bones.
The CMC joint of the thumb or the first CMC joint, also known as the trapeziometaca ...
and the
metacarpophalangeal joint
The metacarpophalangeal joints (MCP) are situated between the metacarpal bones and the proximal phalanges of the fingers. These joints are of the condyloid kind, formed by the reception of the rounded heads of the metacarpal bones into shallow ca ...
.
It also assists in
opposition
Opposition may refer to:
Arts and media
* ''Opposition'' (Altars EP), 2011 EP by Christian metalcore band Altars
* The Opposition (band), a London post-punk band
* '' The Opposition with Jordan Klepper'', a late-night television series on Com ...
and
extension of the thumb.
Additional images
File:Slide1t.JPG, Cadaver dissection
References
{{Authority control
Muscles of the upper limb
Upper limb anatomy