In human anatomy, the adductor pollicis muscle is a muscle in the hand that functions to

adduct An adduct (from the Latin ''adductus'', "drawn toward" alternatively, a contraction of "addition product") is a product of a direct addition of two or more distinct molecules, resulting in a single reaction product containing all atoms of all co ...

the thumb. It has two heads: transverse and oblique. It is a fleshy, flat, triangular, and fan-shaped muscle deep in the thenar compartment beneath the long flexor tendons and the lumbrical muscles at the center of the palm. It overlies the metacarpal bones and the interosseous muscles.

Structure

Oblique head

The oblique head (Latin: ''adductor obliquus pollicis'') arises by several slips from the

capitate bone The capitate bone is a bone in the human wrist found in the center of the carpal bone region, located at the distal end of the radius and ulna bones. It articulates with the third metacarpal bone (the middle finger) and forms the third carpomet ...

, the bases of the second and third

metacarpal In human anatomy, the metacarpal bones or metacarpus form the intermediate part of the skeletal hand located between the phalanges of the fingers and the carpal bones of the wrist, which forms the connection to the forearm. The metacarpal bones ar ...

s, the intercarpal ligaments, and the sheath of the tendon of the

flexor carpi radialis In anatomy, flexor carpi radialis is a muscle of the human forearm that acts to flex and (radially) abduct the hand. The Latin ''carpus'' means wrist; hence flexor carpi is a flexor of the wrist. Origin and insertion The flexor carpi radialis is ...

. Gray's Anatomy 1918. (See infobox) From this origin the greater number of fibers pass obliquely downward and converge to a tendon, which, uniting with the tendons of the medial portion 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 The phalanx ( grc, φάλαγξ; plural phalanxes or phalanges, , ) was a rectangular mass military formation, usually composed entirely of heavy infantry armed with spears, pikes, sarissas, or similar pole weapons. The term is particularly ...

of the thumb, a sesamoid bone being present in the tendon. A considerable

fasciculus ''Fasciculus vesanus'' is an extinct species of stem-group ctenophores known from the Burgess Shale of British Columbia, Canada. It is dated to and belongs to middle Cambrian strata. The species is remarkable for its two sets of long and shor ...

, however, passes more obliquely beneath the tendon of the

flexor pollicis longus The flexor pollicis longus (; FPL, Latin ''flexor'', bender; ''pollicis'', of the thumb; ''longus'', long) is a muscle in the forearm and hand that flexes the thumb. It lies in the same plane as the flexor digitorum profundus. This muscle is un ...

to join the lateral portion of the flexor pollicis brevis and the abductor pollicis brevis.

Transverse head

The transverse head (Latin: ''adductor transversus pollicis'') is deeply seated. It is triangular, arising by a broad base from the lower two-thirds of the palmar surface of the third

bone; the fibers converge, 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

of the thumb.

Relations

The

radial artery In human anatomy, the radial artery is the main artery of the lateral aspect of the forearm. Structure The radial artery arises from the bifurcation of the brachial artery in the antecubital fossa. It runs distally on the anterior part of th ...

passes between the two heads, travelling from the back of the hand into the palm, where it forms the deep palmar arch.

Innervation

The adductor pollicis is innervated by the deep branch of the ulnar nerve (C8–T1). Between the oblique and transverse heads is a thin fibrous arcade which the nerve passes as it traverses the palm laterally. The nerve is accompanied by the deep palmar arch.

Function

While

adduction Motion, the process of movement, is described using specific anatomical terms. Motion includes movement of organs, joints, limbs, and specific sections of the body. The terminology used describes this motion according to its direction relativ ...

of the thumb (bringing it back into the plane of the palm of the hand from its previously abducted position) is mainly produced by the adductor pollicis, it can also bring the thumb to the side of the palm and index finger and the flexor pollicis brevis and the opponens pollicis help in thumb adduction.

Clinical significance

Froment's sign Froment's sign is a special test of the wrist for palsy of the ulnar nerve, specifically, the action of adductor pollicis. Froment's maneuver can also refer to the cogwheel effect from contralateral arm movements seen in Parkinson's disease. __ ...

is used to test for a compromised adductor pollicis muscle. In

neuromuscular monitoring In anesthesia, neuromuscular blocking agents may be required to facilitate endotracheal intubation and provide optimal surgical conditions. When neuromuscular blocking agents are administered, neuromuscular function of the patient must be monitored ...

, the ulnar nerve is stimulated and the strength of adductor pollicis contraction is measured.

Other animals

The adductor pollicis evolved from the contrahens I muscle as man's ancestors' thumbs and

big toe Toes are the digits (fingers) of the foot of a tetrapod. Animal species such as cats that walk on their toes are described as being '' digitigrade''. Humans, and other animals that walk on the soles of their feet, are described as being '' pl ...

s became opposable. It might also contain an element of the thumb's interosseous muscle. In the Pan-Homo LCA the oblique head of the adductor pollicis probably had a relatively small physiological cross sectional area (PCSA) and both heads probably acted as extensors and adductors at 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 ...

. In humans the PCSA of the oblique head is relatively enlarged and both heads act as flexors at this joint.

Additional images

Image:Musculusadductorpollicis.png, The muscles of the thumb. (Adductor pollicis transversus is red band at bottom, and adductor pollicis obliquus is red band immediately above it.) File:Dissection of hand.jpg, Adductor pollicis muscle File:Gray422.png, Transverse section across the wrist and digits. File:Gray427.png, The muscles of the left hand. Palmar surface. File:Gray527.png, The radial and ulnar arteries. File:Gray815.png, Superficial palmar nerves. File:Gray817.png, Deep palmar nerves. File:Gray415.png, Front of the left

forearm The forearm is the region of the upper limb between the elbow and the wrist. The term forearm is used in anatomy to distinguish it from the arm, a word which is most often used to describe the entire appendage of the upper limb, but which in ...

. Deep muscles. (Adductor pollicis visible at bottom center.) File:Froment's_sign.jpg, Negative (above) and positive Froment's sign File:Slide8AAAA.JPG, Adductor pollicis muscle File:Slide6BBBB.JPG, Adductor pollicis muscle File:Slide15BBBB.JPG, Adductor pollicis muscle File:Slide4OOOO.JPG, Adductor pollicis muscle File:Slide14OOOO.JPG, Adductor pollicis muscle

References

* * * * {{Authority control Muscles of the upper limb Hand