Anatomy, Shoulder and Upper Limb, Hand Adductor Pollicis

Excerpt

The musculature of the hand is deeply intricate, with several superimposed layers of muscles, tendons, and fascial compartments throughout. Complex interactions between these groups modulate specific movements, thus understanding their role in hand biomechanics can greatly enhance clinical evaluation and diagnosis for medical professionals.

The thumb is one of the most important entities of the hand. Its versatility in movement compared to the other digits makes the hand the ultimate tool of elite dexterity. Because the thumb is orientated perpendicular to the other digits, its movements are modulated by a diverse set of specific muscles within the hand. Many muscles contribute to its movements, and one of the most important is the adductor pollicis.

The adductor pollicis muscle is an intrinsic muscle of the hand which lies in the deepest muscular plane of the palm, within the adductor compartment. It is a unique muscle, in that it is triangular shaped with a 2-headed structure. The oblique head originates at the capitate as well as at the bases of the 2nd and 3rd metacarpals, while the transverse head originates from the volar aspect of the 3rd metacarpal. These two heads then merge as the fibers travel laterally, forming the tendon of the adductor pollicis which often contains a sesamoid bone. The tendon then inserts on the medial aspect of the proximal phalanx of the thumb as well as the extensor hood.