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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 human thumb also has other muscles in the thenar group (opponens and abductor brevis muscle), moving the thumb in opposition, making grasping possible. The extensors are located on the back of the forearm and are connected in a more complex way than the flexors to the dorsum of the fingers.
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 abductor pollicis brevis is a flat, thin muscle located just under the skin. It is a thenar muscle, and therefore contributes to the bulk of the palm's thenar eminence. It originates from the flexor retinaculum of the hand, the tubercle of the scaphoid bone, and additionally sometimes from the tubercle of the trapezium.
The extrinsic muscle groups are the long flexors and extensors. They are called extrinsic because the muscle belly is located on the forearm. The intrinsic muscle groups are the thenar and hypothenar muscles (thenar referring to the thumb, hypothenar to the small finger), the interossei muscles (between the metacarpal bones, four dorsally and ...
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 .
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.