Opponens pollicis muscle

Opponens pollicis muscle
Opponens pollicis muscle
	The muscles of the thumb
	The muscles of the left hand. Palmar surface.
Details
Origin	trapezium and transverse carpal ligament
Insertion	metacarpal bone of the thumb on its radial side
Nerve	median nerve
Actions	Flexion of the thumb's metacarpal at the first carpometacarpal joint, which aids in opposition of the thumb
Identifiers
Latin	musculus opponens pollicis
TA98	A04.6.02.058
TA2	2525
FMA	37379
	Anatomical terms of muscle [edit on Wikidata]

The opponens pollicis is a small, triangular muscle in the hand, which functions to oppose the thumb. It is one of the three thenar muscles, lying deep to the abductor pollicis brevis and lateral to the flexor pollicis brevis.

Structure

The opponens pollicis originates from the flexor retinaculum of the hand and the tubercle of the trapezium. It passes downward and lateralward, and is inserted into the whole length of the metacarpal bone of the thumb on its radial side.

Innervation

Like the other thenar muscles, the opponens pollicis is innervated by the recurrent branch of the median nerve.

Actions

Opposition of the thumb is a combination of actions that allows the tip of the thumb to touch the tips of other fingers. The part of opposition that this muscle is responsible for is the flexion of the thumb's metacarpal at the first carpometacarpal joint. This specific action cups the palm. Many texts, for simplicity, use the term opposition to represent this component of true opposition. In order to truly oppose the thumb, the actions of a number of other muscles are needed at the thumb's metacarpophalangeal joint.