Unit 4.1 Study Guide

• which term describes the sense of body orientation, movement, and balance?

  equilibrium
• which two structures are important for maintaining equilibrium?

  vestibule of the cochlea and semicircular canals
• which type of equilibrium describes the orientation of the head in space?

  static equilibrium
• which type of equilibrium corresponds to motion and acceleration?

  dynamic equilibrium
• dynamic equilibrium is responsible for two subtypes of acceleration. what are they?

  linear and angular
• which structures in the inner ear are responsible for maintaining equilibrium?

  maculae
• what structure sits on top of the tectorial membrane and helps resist change in motion?

  otoliths
• when our head is upright, there is a steady stream of APs in the vestibular nerve
• when our head is tilted forward, the hair cells bend toward kinocilium
• when our head is tilted forward, the hair cell is depolarized
• when our head is tilted forward, the nerve fiber is excited
• when our head is tilted forward, there is an increase in APs along the vestibular nerve
• when our head is tilted backward, the hair cells bend away from kinocilium
• when our head is tilted backward, the hair cell is hyperpolarized
• when our head is tilted backward, the nerve fiber is inhibited
• when our head is tilted forward, there is an increase in APs along the vestibular nerve
• where are the crista amupullares located?

  semicircular canals
• what are the crista ampullares responsible for?

  angular acceleration
• pairs of crista ampullares have opposite axes, so while one is hyperpolarized, the other one is depolarized
• dizziness is caused from the movement of which fluid of the inner ear?

  endolymph
• which cortex of the brain is responsible for the awareness of spatial orientation and movement?

  vestibular cortex
• which midbrain structure is responsible for eye movement?

  superior colliculus
• which midbrain structure is responsible for the localization of sound?

  inferior colliculus
• which part of the brain is responsible for motor coordination?

  cerebellum
• to which part of the brain is information about equilibrium sent to so that it can be incorporated into the motor plan?

  cerebellum
• which region of the brain is mainly responsible for postural reflexes/movements?

  brain stem
• which two parts of the brain (cortex and region) house upper motor neurons?

  primary motor cortex and brainstem
• how many neurons are there in the lateral and ventral corticospinal pathways?

  2
• where does the first order neuron decussate in the lateral and ventral corticospinal pathway?

  medulla
• what is the pathway of a neural system in the lateral and ventral corticospinal pathway?

  primary motor cortex, midbrain, cerebellum, pons, medulla, cervical spinal cord, lumbar spinal cord, muscles
• what are the pathways outside of pyramidal cells called?

  extrapyramidal pathways
• where to extrapyramidal pathways originate?

  brainstem (red nucleus)
• true or false: all neurons in an extrapyramidal pathway decussate?

  false
• in the example in lecture, which extrapyramidal pathway did we examine?

  rubrospinal tract
• how many neurons are there in the rubrospinal tract?

  2
• the pathway of the rubrospinal tract is as follows: red nucleus, cerebellum, pons, medulla, cervical spinal cord, muscles
• where does the first order neuron in the rubrospinal tract decussate?

  between the red nucleus and cerebellum
• the path of the lower motor neurons are as follows: ventral horn, ventral root, intervertebral foramen, ventral and dorsal rami
• damage to the dorsal regions of the spinal cord can result in what two things?

  loss of sensation or paresthesias
• damage to the ventral regions of the spinal cord can result in which two types of paralysis?

  flaccid and spastic