The thumb has one long flexor and a short flexor in the thenar muscle group. 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. The tendons unite with the interosseous and lumbrical muscles to form the extensorhood mechanism. The primary function of the extensors is to straighten out the digits. The thumb has two extensors in the forearm; the tendons of these form the anatomical snuff box. Also, the index finger and the little finger have an extra extensor, used for instance for pointing. The extensors are situated within six separate compartments. The first compartment contains abductor pollicis longus and extensor pollicis brevis. The second compartment contains extensors carpi radialis longus and brevis. The third compartment contains extensor pollicis longus. The extensor digitorum indicis and extensor digitorum communis are within the fourth compartment. Extensor digiti minimi is in the fifth, and extensor carpi ulnaris is in the sixth. The intrinsic muscle groups are the thenar and hypothenar muscles (thenar referring to the thumb, hypothenar to the small finger), the dorsal and palmar interossei muscles (between the metacarpal bones) and the lumbrical muscles. The lumbricals arise from the deep flexor (and are special because they have no bony origin) and insert on the dorsal extensor hood mechanism.
In English only the digits on the hand are known as fingers. However, in some languages the translated version of fingers can mean either the digits on the hand or feet. In English a digit on a foot has the distinct name of toe. See also
Finger snapping
Fingerprint
Nail (anatomy)
Paroxysmal hand hematoma

Notes
References


== External links ==