249
edits
Changes
Jump to navigation
Jump to search
Quadrupedal Mechanics - Anatomy & Physiology (view source)
Revision as of 22:05, 28 November 2013
, 22:05, 28 November 2013→Limbs as pendulums
The main movement for propulsion is protraction—retraction. It is useful to regard each limb as a pendulum, swinging in a sagittal plane. During slow locomotion, the pivot for the hindlimb is the hip joint (Fig 8.4 a). For the forelimb, the pivot is not the shoulder, but is more proximal (Figs 5.3, 8.3 b, 8.4 b).
The main movement for propulsion is protraction—retraction. It is useful to regard each limb as a pendulum, swinging in a sagittal plane. During slow locomotion, the pivot for the hindlimb is the hip joint (Fig 8.4 a). For the forelimb, the pivot is not the shoulder, but is more proximal (Figs 5.3, 8.3 b, 8.4 b).
[[File:QMFig 8.4.png|thumb|'''Fig 8.4 Limb movements of a walking cat''']]
:::::'''Fig 8.4 Limb movements of a walking cat'''
:::::'''Fig 8.4 Limb movements of a walking cat'''
::::::1 Foot leaves ground.
::::::1 Foot leaves ground.
::::::2. Foot contacts ground. Stifle, hock and elbow are extending.
::::::2. Foot contacts ground. Stifle, hock and elbow are extending.
::::::2-1 Retraction, or stance phase. Stifle, hock and elbow continue extending. Hip and shoulder are lowered slightly.
::::::2-1 Retraction, or stance phase. Stifle, hock and elbow continue extending. Hip and shoulder are lowered slightly.
The movements of the joints of each limb are small compared with the movements of the limb as a whole. The movement during walking is therefore best described as that of a pendulum with a pivot at the hip for the hindlimb. The pivot for the forelimb, however, lies proximally to the shoulder joint.
==='''The effect of size on pendulums'''===
==='''The effect of size on pendulums'''===