VPB 121: Veterinary Physiology - II (2+1)

Importance of equatorial region

IMPORTANCE OF EQUTORIAL REGION

• Action potential are generated from this region by stretching
• Muscle spindle receptors lie parallel to the extra fusal fibres.
• Functionally these receptors are connected to the origin and insertion of the tendon i.e. lengthening of the whole muscle will stretch the equatorial region.
• Contraction of polar ends also generate action potential, which passes in the sensory nerve, in proportion to lengthening of the equatorial region.
• Sensory fibres are capable of detecting the changes in length during the dynamic phase of muscle lengthening and during resting stage.
• When CNS receives the sensory inception, it causes excitatory mono-synaptic connection with alpha-motor neurons (that supplies extra fusal fibres of the same muscle)
• This leads to contraction of the whole muscle which results in shortening of the muscle spindle (especially the equatorial region)
• This shuts-off the action potential from spindle receptor and muscle contraction is stopped.