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Anatomists and other researchers focused on human anatomy have hundreds of definitions of opposition. [4] Some anatomists [5] restrict opposition to when the thumb is approximated to the fifth finger (little finger) and refer to other approximations between the thumb and other fingers as apposition.
It adducts the thumb, and assists in opposition and flexion. It is innervated by the deep branch of the ulnar nerve (C8-T1). [6] The first dorsal interosseous, one of the central muscles of the hand, extends from the base of the thumb metacarpal to the radial side of the proximal phalanx of the index finger. [7]
The thenar eminence is the mound formed at the base of the thumb on the palm of the hand by the intrinsic group of muscles of the thumb. [1] The skin overlying this region is the area stimulated when trying to elicit a palmomental reflex. The word thenar comes from Ancient Greek θέναρ (thenar) 'palm of the hand'. [2]
The radial nerve innervates the finger extensors and the thumb abductor; that is, the muscles that extend at the wrist and metacarpophalangeal joints (knuckles) and abduct and extend the thumb. The median nerve innervates the flexors of the wrist and digits, the abductors and opponens of the thumb, the first and second lumbricals. The ulnar ...
Left hand shown with thumb on left. The metacarpals form a transverse arch to which the rigid row of distal carpal bones are fixed. The peripheral metacarpals (those of the thumb and little finger) form the sides of the cup of the palmar gutter and as they are brought together they deepen this concavity.
Joints of the hand, X-ray Interphalangeal ligaments and phalanges. Right hand. Deep dissection. Posterior (dorsal) view. The PIP joint exhibits great lateral stability. Its transverse diameter is greater than its antero-posterior diameter and its thick collateral ligaments are tight in all positions during flexion, contrary to those in the metacarpophalangeal joint.
Abduction of the thumb is defined as the movement of the thumb anteriorly, a direction perpendicular to the palm. The abductor pollicis brevis does this by acting across both the carpometacarpal joint and the metacarpophalangeal joint. It also assists in opposition and extension of the thumb.
In human anatomy, the adductor pollicis muscle is a muscle in the hand 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.