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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.
SBA Answers and Explanations
Published in Vivian A. Elwell, Jonathan M. Fishman, Rajat Chowdhury, SBAs for the MRCS Part A, 2018
Vivian A. Elwell, Jonathan M. Fishman, Rajat Chowdhury
The history described earlier is typical of carpal tunnel syndrome. Entrapment of the median nerve at the carpal tunnel affects the muscles of the thenar eminence. These are abductor pollicis brevis, flexor pollicis brevis, and opponens pollicis. The nerve supply of flexor pollicis brevis is extremely variable, however, so the best test to perform would be to see if opposition is affected. In addition, the motor branch of the median nerve after the level of the carpal tunnel also innervates the radial (lateral) two lumbricals.
The effects of pistol grip power tools on median nerve pressure and tendon strains
Published in International Journal of Occupational Safety and Ergonomics, 2022
Ryan Bakker, Mayank Kalra, Sebastian S. Tomescu, Robert Bahensky, Naveen Chandrashekar
The arms were dissected to expose and isolate the wrist flexor and extensor tendons from their muscle bodies. Specifically, those muscle tendons providing the largest individual contributions to wrist stabilization during a maximum gripping task were exposed as described by Rossi et al. [17]. These included the tendons of the FDP, FDS, extensor digitorum communis (EDC), extensor carpi radialis brevis, extensor digitorum indicis, extensor pollicis longus and extensor carpi radialis longus. Tendons from the muscles that contribute to gripping but do not cross the wrist joint, such as the adductor pollicis oblique head and flexor pollicis brevis, were not exposed. Each of the five exposed tendons was sutured to a stainless-steel cable using surgical sutures. The FDS, FDP and EDC muscles each have four individual tendons that were sutured together to their individual cables.
Epithelioid sarcoma of the hand: a wolf in sheep's clothing
Published in Journal of Plastic Surgery and Hand Surgery, 2021
Jonathan Persitz, Eran Beit Ner, Igal Chechik, Timoret Keren, Erez Avisar
Due to this exceptional case, a sarcoma multidisciplinary team was gathered including representatives of the orthopaedic hand surgery unit, radiology department, plastic surgery department, oncology and an onco-orthopaedic specialist. The joint decision was to address this subdermal lesion as a high grade epithelioid STS. The patient underwent a PET-CT scan, which did not show any nodal involvement, after which, a surgical plan was conducted. Treatment included wide resection (over 2 cm margins), followed by a reconstruction procedure with proximally based thenar flap (flexor pollicis brevis and abductor pollicis brevis) and split thickness skin graft (Hip) placed on a MatriDerm® (Figures 2 and 3). A local adjuvant radiotherapy treatment was given post-op. Final pathology report concluded that the specimen’s characteristics are of epithelioid STS. The patient is disease free, four years after the day of resection, with an incorporated skin graft.