NROC64H3 Chapter Notes - Chapter 11: Semicircular Canals, Nystagmus, Otolith
Document Summary
Maintaining upright posture in man is hard. Vertical projection of centre of gravity must lie w/in region of support area. Controlled by moving feet relative to centre of gravity or vice versa. 2 sources of info let us do this: pressure receptors in feet and head (vestibular and visual systems) If suspend decerebtrate animal and push on one fot; animal responds by extending corresponding limb. Extensor thrust: transient component, accompanied by stifferning of limb and arching back. Buttress reaction: ex. when you pull dog forward; extension of front feet. Postural sway reaction: if body pushed from side; shift in pressure on feet results in extension of limbs on opposite side and retraction of others. Stepping reactions: if projection of centre of gravity mvoed outside critical area, this automatic rxn is elicited to track centre of gravity. Vestibular apparatus gives 2 types of info about head: angular. Velocity from semicircular canals, attitude relative to effective direction of gravity from otolith organs.
