Postural control and locomotion

Question 1

where do the lateral vestibulospinal and pontine reticulospinal tracts go? what is their role?

Answer 1

1. entire length of spinal cord 2. facilitate motor neurons of extensor muscles

Question 2

what pathway(s) cause decerebrate posturing?

Answer 2

ventromedial pathways (extensor drive)

Question 3

where does the medial vestibulospinal tract go? what is its function?

Answer 3

1. as far as upper thoracic spinal cord 2. mediates reflex head movements in response to vestibular stimuli

Question 4

what is the sensory input for cervicocollic reflex?

Answer 4

proprioceptive input from neck muscle spindles and joint receptors

Question 5

what is the sensory input for the tonic neck reflexes?

Answer 5

vestibular

Question 6

what is the sensory input for labyrinth righting reflex?

Answer 6

vestibular

Question 7

what kind of patient would exhibit an asymmetrical tonic neck reflex? symmetrical?

Answer 7

1. asymmetric - young infants or children with cerebral palsy 2. symmetric - infants 4-6 months of age or people with cerebral damage

Question 8

what are stepping pattern generators (SPGs) and what do they do?

Answer 8

networks of spinal interneurons that control stepping movements at hips and knees

Question 9

what is decerebrate posture? what causes it?

Answer 9

1. extension of all four limbs and neck 2. lesion of upper pons leading to increased facilitation of extensor LMNs - massive excitation of gamma loop

Question 10

what is decorticate posture? what causes it?

Answer 10

1. arms flexed and legs extended 2. lesion of internal capsule or upper midbrain that releases both vestibulospinal and tonic neck reflexes from cortical control

Question 11

what is vection?

Answer 11

perception of self-motion induced by visual stimuli