TY - JOUR
T1 - Moment arms about the carpal and metacarpophalangeal joints for flexor and extensor muscles in equine forelimbs
AU - Brown, Nicholas A.T.
AU - Pandy, Marcus G.
AU - Buford, William L.
AU - Kawcak, Christopher E.
AU - McIlwraith, C. Wayne
PY - 2003
Y1 - 2003
N2 - Objective: To determine whether muscle moment arms at the carpal and metacarpophalangeal joints can be modeled as fixed-radius pulleys for the range of motion associated with the stance phase of the gait in equine forelimbs. Sample Population: 4 cadaveric forelimbs from 2 healthy Thoroughbreds. Procedure: Thin wire cables were sutured at the musculotendinous junction of 9 forelimb muscles. The cables passed through eyelets at each muscle's origin, wrapped around single-turn potentiometers, and were loaded. Tendon excursions, measured as the changes in lengths of the cables, were recorded during manual rotation of the carpal (180° to 70°) and metacarpophalangeal (220° to 110°) joints. Extension of the metacarpophalangeal joint (180° and 220°) was forced with an independent loading frame. Joint angle was monitored with a calibrated potentiometer. Moment arms were calculated from the slopes of the muscle length versus joint angle curves. Results: At the metacarpophalangeal joint, digital flexor muscle moment arms changed in magnitude by ≤ 38% during metacarpophalangeal joint extension. Extensor muscle moment arms at the carpal and metacarpophalangeal joints also varied (≤ 41% at the carpus) over the range of joint motion associated with the stance phase of the gait. Conclusions and Clinical Relevance: Our findings suggest that, apart from the carpal flexor muscles, muscle moment arms in equine forelimbs cannot be modeled as fixed-radius pulleys. Assuming that muscle moment arms at the carpal and metacarpophalangeal joints have constant magnitudes may lead to erroneous estimates of muscle force in equine forelimbs.
AB - Objective: To determine whether muscle moment arms at the carpal and metacarpophalangeal joints can be modeled as fixed-radius pulleys for the range of motion associated with the stance phase of the gait in equine forelimbs. Sample Population: 4 cadaveric forelimbs from 2 healthy Thoroughbreds. Procedure: Thin wire cables were sutured at the musculotendinous junction of 9 forelimb muscles. The cables passed through eyelets at each muscle's origin, wrapped around single-turn potentiometers, and were loaded. Tendon excursions, measured as the changes in lengths of the cables, were recorded during manual rotation of the carpal (180° to 70°) and metacarpophalangeal (220° to 110°) joints. Extension of the metacarpophalangeal joint (180° and 220°) was forced with an independent loading frame. Joint angle was monitored with a calibrated potentiometer. Moment arms were calculated from the slopes of the muscle length versus joint angle curves. Results: At the metacarpophalangeal joint, digital flexor muscle moment arms changed in magnitude by ≤ 38% during metacarpophalangeal joint extension. Extensor muscle moment arms at the carpal and metacarpophalangeal joints also varied (≤ 41% at the carpus) over the range of joint motion associated with the stance phase of the gait. Conclusions and Clinical Relevance: Our findings suggest that, apart from the carpal flexor muscles, muscle moment arms in equine forelimbs cannot be modeled as fixed-radius pulleys. Assuming that muscle moment arms at the carpal and metacarpophalangeal joints have constant magnitudes may lead to erroneous estimates of muscle force in equine forelimbs.
UR - http://www.scopus.com/inward/record.url?scp=0038386064&partnerID=8YFLogxK
U2 - 10.2460/ajvr.2003.64.351
DO - 10.2460/ajvr.2003.64.351
M3 - Article
C2 - 12661877
AN - SCOPUS:0038386064
SN - 0002-9645
VL - 64
SP - 351
EP - 357
JO - American Journal of Veterinary Research
JF - American Journal of Veterinary Research
IS - 3
ER -