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Quadrupedal Mechanics - Anatomy & Physiology (view source)
Revision as of 22:16, 28 November 2013
, 22:16, 28 November 2013→Short and longheaded muscles
==='''Short and longheaded muscles'''===
==='''Short and longheaded muscles'''===
Over most joints, there are muscles with actions limited to a particular single joint, as in Fig. 6.3, and other muscles that, in addition, act over adjacent joints (Fig. 8.8). It is convenient to call muscles acting over a single joint "shortheaded", and muscles acting over more than one joint, "longheaded". This nomenclature concurs with, for instance, that used for the long head of M. triceps brachii, as well as the short and long digital extensor muscles of the hindlimb.
Over most joints, there are muscles with actions limited to a particular single joint, as in Fig. 6.3, and other muscles that, in addition, act over adjacent joints (Fig. 8.8). It is convenient to call muscles acting over a single joint "shortheaded", and muscles acting over more than one joint, "longheaded". This nomenclature concurs with, for instance, that used for the long head of M. triceps brachii, as well as the short and long digital extensor muscles of the hindlimb.
[[File:QMFig 8.8.png|thumb|'''Fig 8.8 Short and longheaded muscles''']]
:::::'''Fig 8.8 Short and longheaded muscles'''
:::::'''Fig 8.8 Short and longheaded muscles'''
:::::The pairs of counteractive muscles shown in the hindlimb of the dog (a) are m. rectus femoris and m. semitendinosus, as longheaded muscles, and m. vastus lateralis and m. adductor as shortheaded muscles. Muscle lengths are compared between the flexed hip and stifle position (b) and the extended position (c). The longheaded muscles tend to maintain a constant length over a natural range of limb function.
:::::The pairs of counteractive muscles shown in the hindlimb of the dog (a) are m. rectus femoris and m. semitendinosus, as longheaded muscles, and m. vastus lateralis and m. adductor as shortheaded muscles. Muscle lengths are compared between the flexed hip and stifle position (b) and the extended position (c). The longheaded muscles tend to maintain a constant length over a natural range of limb function.
==='''A severe restriction on muscle function: active insufficiency'''===
==='''A severe restriction on muscle function: active insufficiency'''===