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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 intrinsic muscles of the thumb can be divided into two groups; the thenar eminence and other muscles. The thenar eminence refers to the group of muscles on the palm at the base of the thumb. The three muscles composing the thenar eminence are the abductor pollicis brevis, flexor pollicis brevis and opponens pollicis. [5] The other two ...
The muscles of the hand are the skeletal muscles responsible for the movement of the hand and fingers. The muscles of the hand can be subdivided into two groups: the extrinsic and intrinsic muscle groups. The extrinsic muscle groups are the long flexors and extensors. They are called extrinsic because the muscle belly is located on the forearm ...
In the thenar eminence, the recurrent branch of the median nerve provides motor innervation to: [4] opponens pollicis muscle; abductor pollicis brevis muscle; superficial part of flexor pollicis brevis muscle; A separate, more proximal branch of the median nerve additionally provides motor innervation to the 1st and 2nd lumbricals of the hand.
The deep muscles arise from the distal part of the ulna and the surrounding interosseous membrane. The brachioradialis , flexor of the elbow , is unusual in that it is located in the posterior compartment, but it is actually a muscle of flexor / anterior compartment of the forearm.
The intrinsic muscle groups are the thenar (thumb) and hypothenar (little finger) muscles; the interosseous muscles (four dorsally and three volarly) originating between the metacarpal bones; and the lumbrical muscles arising from the deep flexor (and are special because they have no bony origin) to insert on the dorsal extensor hood mechanism ...
The muscles of the thumb can be compared to guy-wires supporting a flagpole; tension from these muscular guy-wires must be provided in all directions to maintain stability in the articulated column formed by the bones of the thumb. Because this stability is actively maintained by muscles rather than by articular constraints, most muscles ...
The muscle's superficial head arises from the distal edge of the flexor retinaculum and the tubercle of the trapezium, the most lateral bone in the distal row of carpal bones. [1] It passes along the radial side of the tendon of the flexor pollicis longus. The deeper (and medial) head "varies in size and may be absent."