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Anatomy
Published in Peter Houpt, Hand Injuries in the Emergency Department, 2023
The median nerve runs between the two bellies of the pronator teres muscle in the forearm. It continues between the flexor digitorum superficialis and profundus muscles to the carpal tunnel. During this course it branches off the anterior interosseous nerve to the m. flexor pollicis longus, the m. flexor digitorum profundus of the index finger and m. pronator quadratus. The median nerve itself innervates the m. flexor carpi radialis, the m. pronator teres, the four mm. flexor digitorum superficialis, the m. palmaris longus and the m. flexor digitorum profundus to the middle finger. At the level of the wrist, the median nerve is located on the ulnar side of the FCR and is covered by the palmaris longus tendon. Distally, the median nerve passes through the carpal tunnel underneath the transverse carpal ligament. The motor branch branches off to the thenar and innervates the m. opponens pollicis, the m. abductor brevis and half of the m. flexor pollicis brevis. Finally the median nerve branches off as a sensory nerve to the thumb, index, middle and radial half of the ring finger.
A to Z Entries
Published in Clare E. Milner, Functional Anatomy for Sport and Exercise, 2019
The muscles of the hand can be divided into three groups; those of the thumb (thenar muscles), the little finger (hypothenar muscles), and the palmar region between the metacarpals. The muscles of the thumb are abductor pollicis brevis, opponens pollicis, adductor pollicis, and flexor pollicis brevis, which variously abduct, adduct, and flex the thumb. Opponens pollicis also rotates the first metacarpal to bring the thumb in front of the palm facing the fingers, the opposed position that enables the hand to grip objects firmly between the thumb and fingers. The muscles of the little finger are the abductor digiti minimi, flexor digiti minimi brevis, and opponens digiti minimi. These muscles abduct and flex the little finger. The opponens digiti minimi also rotates the fifth metacarpal, so that the little finger faces the thumb; like the opposition of the thumb, this contributes to the ability of the hand to grasp effectively. The muscles of the palmar region are the lumbricals and the dorsal and palmar interossei, which flex the metacarpophalangeal joints (knuckles) and extend the interphalangeal joints of the fingers. The palmar interossei also adduct the fingers towards the middle finger and the dorsal interossei have the opposite function of abducting the fingers.
Upper limb
Published in Aida Lai, Essential Concepts in Anatomy and Pathology for Undergraduate Revision, 2018
Attachments of opponens pollicis– origin: tubercle of trapezium– insertion: lat. palmar surface of first metacarpal bone– nerve SS: recurrent branch of median n. (C8, T1)– function: medially rotate thumb
Innervation of the lumbrical and interosseous muscles in hand: analysis of distribution of nerve fascicles and quantification of their surface projections
Published in Journal of Plastic Surgery and Hand Surgery, 2022
Our results quantitatively visualized the locations of the branches innervating LMs and IMs, suggestively solving the diagnosis puzzle in patients with isolated dysfunction of the lumbrical or interosseus resulting from an injury to the palm region. In high median or ulnar nerve lesions, reinnervation of the intrinsic muscles is impossible because of the long distance over which axons regenerate. Nerve transfer may be a potential decision to reconstruct the function of intrinsic muscles because of the shortened distance. Previously, a procedure for transferring the motor branch of the abductor digiti quinti to reinnervate thenar muscles in patients with high MN injuries was reported [21]. The patients involved in this study recovered near 75% of grasp and pinch strength compared with their normal side. Additionally, Bertelli [22] reported a procedure that transferring the branch of the opponens pollicis to the terminal division of the deep branch of the ulnar nerve for pinch reconstruction. The patients involved in this study had 80–90% improvement in pinch-to-zoom strength. Colonna [23] introduced a novel method for transferring the L1’s branch to the distal ulnar nerve motor branch in a cadaveric study. Our findings may be helpful in designing procedures for transfer of motor branches of LMs and IMs. In our results, the distance between the origin of the branch of the L1 (29.81, 44.67) and the entrance of the branch of the D1 (19.39, 41.88) was short, that can provided support to Colonna’s study [23] and broadened Bertelli’s study [22].
Effect of hand postures and object properties on forearm muscle activities using surface electromyography
Published in International Journal of Occupational Safety and Ergonomics, 2020
Kyung-Sun Lee, Myung-Chul Jung
The properties of an object, i.e., its size and weight, also affect the physical load on the hand and wrist [8]. Ayoub and Presti [15] studied the effect of the size of a cylindrical handle on forearm muscle activities. They found that a cylinder with a diameter of 6.25 cm caused the least forearm muscle activity. Berguer et al. [10] estimated the difference in muscle activities caused by the shape and size of objects such as inline and pistol laparoscopic surgical instruments. They observed that using a pistol-type instrument with a palm grip decreased the activities in the FDS, extensor carpi ulnaris (ECU), thenar compartment and extensor digitorum communis muscles. Alaerts et al. [16] found that the maximum amplitudes of the opponens pollicis, flexor carpi radialis (FCR) and extensor carpi radialis (ECR) muscles increased when lifting heavy objects, and Kurita et al. [17] found that the weight of an object did not affect the electromyographic activities of the adductor pollicis brevis.