05c posture and balance
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Vestibular System
Overview of Vestibular System
1. Detects motion of head in space to control head and body posture and eye movement
2. Provide subjective sense of movement and orientation in space
The Vestibular system
The Maculae are responsible for (linear acceleration forces) Detecting Orientation of the Head with Respect to GravityThe Maculae are in the
– Saccule : is responsible forvertical acceleration– Utricle: Is responsible forhorizontal acceleration
Saccule
Utricle
Vestibular Hair Cells
Macule and Hair Cell
Vestibular transduction of Mechanical Stimuli
Morphological polarization of hair cells in the utricular and saccular maculae
Forces acting on the head and the resulting displacement of the otolithicmembrane of the utricular macula
Response of a vestibular nerve axon from an otolith organ
Vestibular Navigation
The Semicircular Canals Detect Angular Accelerations
The ampulla is responsible for the change in rotational movement
Vestibular Inputs
Posture and Balance
Postural adjustments require anticipatory motor actions.
Anticipatory maintenance of body posture
Anticipatory motor action in response to postural disturbance
Appropriate anticipatory responses to postural disturbances can be learned
Adaptive Postural Control Is Learned During Locomotion
The vestibular contribution to postural adjustment depends on whether the primary perturbation is to the feet or the head
Decerebrate Rigidity
Upper Motor Neurons That Maintain Balance and Posture