Sensory Neuroscience Flashcards
The _______ _____ is important for balance, the coordination of where your limbs are in space, also known as proprioception, eye movements, and posture.
Vestibular System
What are the 3 semicircular canals?
Anterior (Sagittal)
Lateral (Transverse)
Posterior (Coronal)
T/F
The anterior canal is sensitive to up-down movements like when you nod your head. Another way to think of this is rotation in the sagittal plane.
TRUE
T/F
The fluid in the lateral canal moves the most following changes along the vertical axis. This occurs, for example, when you turn your head to the left- and right-hand sides before crossing a road. This is rotation in the transverse plane.
TRUE
T/F
The superior canal detects movements like when you try to touch your right ear to your right deltoid. The superior canal would also detect a cartwheel. This is rotation in the coronal plane.
TRUE
What are the 2 otolith organs that detect linear acceleration and head positioning?
Utricle- horizontal
Saccule- vertical
T/F
The utricle is smaller than the saccule and connects with each of the semi-circular canals.
FALSE
Utricle is larger than the saccule
Where is the saccule located?
Between the utricle and the cochlea
Which 3 cranial nerves are right at the pon-medullary border?
Abducens (VI) most medial
Facial (VII)
Vestibulochoclear (VIII) most lateral
T/F
The vestibular neurons of the 8th cranial nerve travel to vestibular nuclei in the upper medulla and lower brainstem. Some of these nuclei project to the same side of the body, some project bilaterally, and some project to the other side. The signal is relayed to thalamus and then to the cerebral cortex. The thalamic nuclei where this occurs may be the ventrobasal. Signals from the thalamus are relayed to an as yet undetermined location in the cerebral cortex.
TRUE
Reflex: involuntary response to a stimulus
Head turns left, eyes move right
Abducens (CN VI): controls lateral rectus
Vestibuloocular Reflec (VOR)
Lacteral rectus is innervated by the abducens (activation leads to outwards gaze)
In comatose patients, what test provides information about brainstem function?
Caloric Test
_____ refers to rapid involuntary eye movements. The _____is the wider diameter portion of the semicircular canals where they make contact with the utricle.
A. Nystagmus
B. Ampulla
Involves infusing water of different temperatures into the external auditory canal.
Application of water to the right ear that is colder than body temperature causes the endolymph in the semicircular canal to fall.
When the patient is lying down, the lateral semicircular canal is particularly important in this process. This decreases the firing rate of neurons that project to the brainstem. The eyes will normally slowly drift to the right than they will reverse and quickly move to the left in jerky small motions.
The reverse is true for warm water applied to the right ear. Eyes will slowly drift to the left. Then they will reverse direction and quickly dart to the right.
Generations of medical students have learned the acronym COWS which refers to the fast portion, Cold Opposite, Warm Same.
Caloric Test
Involves episodes of vertigo or spinning and often nausea. Treatment can involve waiting as this often resolves in a couple months. There are also strategies of positioning the head in a pattern to move the crystal from the semi-circular canal back to the utricle.
Benign Paroxysmal Positional Vertigo
