The Brain 3

Question 1

what is the vestibular apparatus?

Answer 1

part of the ear concerned with equilibrium and balance
composed of 3 semi0circular canals and 2 chambers (utricle and saccule)

Question 2

what is the function of the vestibular apparatus?

Answer 2

signals changes in position of the head in space and with sensory input from visual and position receptors, contributes to the maintenance of posture and balance

Question 3

how does the vestibular apparatus respond when the head is tilted?

Answer 3

Stimulation of the hair cells causes them to bend in a particular direction -> depolarization (excitation) or hyperpolarization
(inhibition)
Bending of these hair cells -> action potentials in the vestibular portion of the cranial nerve VIII -> impulses are relayed to the vestibular nuclei

Question 4

what is a reflex?

Answer 4

a reflex is an automatic response to a stimulus mediated within the brain or spinal cord, reflexes involve an orderly sequence of events called a reflex arc.

Question 5

what midbrain upper motor neuron pathways influence movement?

Answer 5

• vestibulospinal tract -> lower motor neuron
• reticulospinal tract
• rubrospinal tract
• superior and inferior colliculi