thenar eminence
Pronunciation: THEE-nar
Muscular prominence at the base of the thumb containing muscles essential for thumb opposition and grip.
Full Definition
The thenar eminence is the rounded muscular prominence located at the base of the thumb on the palmar aspect of the hand. It contains four intrinsic muscles: the abductor pollicis brevis, flexor pollicis brevis, opponens pollicis, and adductor pollicis. These muscles are innervated primarily by the recurrent branch of the median nerve, with the deep head of flexor pollicis brevis and adductor pollicis receiving innervation from the ulnar nerve. The thenar muscles are crucial for thumb opposition, pinch grip, and fine motor control. Atrophy of the thenar eminence is a significant clinical finding that may indicate median nerve pathology, such as severe carpal tunnel syndrome.
Usage
Usage note: Distinguish from hypothenar eminence, which is located at the base of the little finger.
In Context
- "Visible thenar eminence atrophy suggested advanced carpal tunnel syndrome." — Physical examination
- "The thenar eminence showed good muscle bulk with intact opposition strength." — Neurological assessment