Adductor pollicis muscle


Image by/from CFCF

In human anatomy, the adductor pollicis muscle is a muscle in the hand that operates to adduct the thumb. It has 2 heads: transverse and oblique.

It is a fleshy, flat, triangular, and fan-shaped muscle deep in the thenar compartment underneath the long flexor tendons and the lumbrical muscles at the center of the palm. It overlies the metacarpal bones and the interosseous muscles.

The oblique head (Latin: adductor obliquus pollicis) emerges by numerous slips from the capitate bone, the bases of the 2nd and 3rd metacarpals, the intercarpal ligaments, and the sheath of the tendon of the flexor carpi radialis.

From this origin the higher number of fibers pass obliquely down and merge to a tendon, which, unifying with the tendons of the medial part of the flexor pollicis brevis and the transverse head of the adductor pollicis, is inserted into the ulnar side of the base of the proximal phalanx of the thumb, a sesamoid bone existing in the tendon.

A substantial fasciculus, nevertheless, passes more obliquely underneath the tendon of the flexor pollicis longus to join the lateral part of the flexor pollicis brevis and the abductor pollicis brevis.

The transverse head (Latin: adductor transversus pollicis) is deeply seated.

It is triangular, emerging by a broad base from the lower two-thirds of the palmar surface of the 3rd metacarpal bone; the fibers merge, to be inserted with the medial part of the flexor pollicis brevis and the oblique head into the ulnar side of the base of the proximal phalanx of the thumb.

The radial artery passes in between the 2 heads, passing from the back of the hand into the palm, where it forms the deep palmar arch.

The adductor pollicis is innervated by the deep branch of the ulnar nerve (C8-T1).

In between the oblique and transverse heads is a thin fibrous arcade which the nerve passes as it passes through the palm laterally. The nerve is accompanied by the deep palmar arch.

While adduction of the thumb (bringing it back into the plane of the palm of the hand from its formerly abducted position) is primarily produced by the adductor pollicis, it can likewise bring the thumb to the side of the palm and forefinger and the flexor pollicis brevis and the opponens pollicis aid in thumb adduction.

Froment’s sign is utilized to evaluate for a compromised adductor pollicis muscle.

In neuromuscular tracking, the ulnar nerve is activated and the strength of adductor pollicis contraction is evaluated.

The adductor pollicis evolved from the contrahens I muscle as man’s forefathers’ thumbs and huge toes ended up being opposable. It may likewise consist of an aspect of the thumb’s interosseous muscle.

In the Pan-Homo LCA the oblique head of the adductor pollicis most likely had a fairly little physiological cross sectional area (PCSA) and both heads most likely served as extensors and adductors at the carpometacarpal joint. In human beings the PCSA of the oblique head is reasonably bigger and both heads serve as flexors at this joint.

The muscles of the thumb. (Adductor pollicis transversus is red band at bottom, and adductor pollicis obliquus is red band rapidly above it.).

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