In
human anatomy, the adductor pollicis muscle is a
muscle
Muscle is a soft tissue, one of the four basic types of animal tissue. There are three types of muscle tissue in vertebrates: skeletal muscle, cardiac muscle, and smooth muscle. Muscle tissue gives skeletal muscles the ability to muscle contra ...
in the
hand
A hand is a prehensile, multi-fingered appendage located at the end of the forearm or forelimb of primates such as humans, chimpanzees, monkeys, and lemurs. A few other vertebrates such as the Koala#Characteristics, koala (which has two thumb#O ...
that functions to
adduct 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 bases of the second and third
metacarpals, the intercarpal ligaments, and the sheath of the tendon of the
flexor carpi radialis.
[ 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 of the thumb, a
sesamoid bone being present in the tendon.
A considerable
fasciculus, however, passes more obliquely beneath the tendon of the
flexor pollicis longus 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
metacarpal 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
phalanx of the
thumb.
Relations
The
radial artery 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 is used to test for a compromised adductor pollicis muscle.
In
neuromuscular monitoring, 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 Digit (anatomy), digits 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 ' ...
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. In humans the PCSA of the oblique head is relatively enlarged and both heads act as flexors at this joint.
See also
*
Adductor hallucis muscle
The Adductor hallucis (adductor obliquus hallucis) arises by two heads—oblique and transverse and is responsible for adducting the big toe. It has two heads, both are innervated by the lateral plantar nerve.
Structure Oblique head
The ''obliqu ...
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:Carpal-Tunnel.svg, 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. 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
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{{Authority control
Muscles of the upper limb
Hand