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Quadrupedal Mechanics - Anatomy & Physiology (view source)
Revision as of 03:38, 29 November 2013
, 03:38, 29 November 2013→Motion without change of location
'''Standing up:''' The smaller the animal, the more easily it can spring to its feet with a sudden back movement, but even horses can manage to do this. A slower, more deliberate movement is, for the dog, cat and pig, essentially the reverse process of lying down. Cattle and sheep raise themselves up on to their hindlimbs first, then on to their flexed carpuses. The horse rolls its trunk to sternal recumbency, collects its four legs underneath, and then protracts and extends its forelimbs, raising its cranial trunk before its caudal trunk, by pushing its weight over its forelimbs with a thrust from the hindlimbs.
'''Standing up:''' The smaller the animal, the more easily it can spring to its feet with a sudden back movement, but even horses can manage to do this. A slower, more deliberate movement is, for the dog, cat and pig, essentially the reverse process of lying down. Cattle and sheep raise themselves up on to their hindlimbs first, then on to their flexed carpuses. The horse rolls its trunk to sternal recumbency, collects its four legs underneath, and then protracts and extends its forelimbs, raising its cranial trunk before its caudal trunk, by pushing its weight over its forelimbs with a thrust from the hindlimbs.
[[File:QMFig 10.5.png|thumb|'''Fig 10.5 Stable positions for the horse on its hindlimbs''']]
'''Standing on hindlimbs:''' In order to achieve this, the centre of gravity must lie vertically above the hindfeet (Fig. 10.5 a, b). This is easier for horses than cattle. Horses can prance and kick with their forelimbs, but cattle cannot. A copulating bull can maintain the position only briefly, and uses the cow for support. Standing on hindlimbs is especially easy for animals with a more caudally located centre of gravity (Fig. 10.2 b).
'''Standing on hindlimbs:''' In order to achieve this, the centre of gravity must lie vertically above the hindfeet (Fig. 10.5 a, b). This is easier for horses than cattle. Horses can prance and kick with their forelimbs, but cattle cannot. A copulating bull can maintain the position only briefly, and uses the cow for support. Standing on hindlimbs is especially easy for animals with a more caudally located centre of gravity (Fig. 10.2 b).
[[File:QMFig 10.6.png|thumb|'''Fig 10.6 Propulsion and friction forces''']]
:::::'''Fig 10.5 Stable positions for the horse on its hindlimbs'''
:::::'''Fig 10.5 Stable positions for the horse on its hindlimbs'''
:::::'''Fig 10.6 Propulsion and friction forces'''
:::::'''Fig 10.6 Propulsion and friction forces'''
:::::The insertion of a plate between the hose and the ground enables the forces acting on the body during a propulsive movement of the hindlimbs during the gallop to be visualised.
:::::The insertion of a plate between the hose and the ground enables the forces acting on the body during a propulsive movement of the hindlimbs during the gallop to be visualised.
==='''Propulsive force'''===
==='''Propulsive force'''===