Books
in black and white
Main menu
Share a book About us Home
Books
Biology Business Chemistry Computers Culture Economics Fiction Games Guide History Management Mathematical Medicine Mental Fitnes Physics Psychology Scince Sport Technics
Ads

Board Review Series - Fix J.D.

Fix J.D. Board Review Series - London, 1995. - 430 p.
Download (direct link): boardreviewseries1995.djvu
Previous << 1 .. 75 76 77 78 79 80 < 81 > 82 83 84 85 86 87 .. 351 >> Next

-detect and respond to the position of the head with respect to linear
acceleration and the pull ogf ravity.
-are endolymph-containing dilatations of the membranous labyrinth, -
are located within the vestibule of the bony labyrinth, -contain hair
cells in the macula of the utricle and the macula of the
saccule.
a. Maculae of the utricle and saccule
-are two patches of sensory epithelium,
-consist of supporting cells and hair cells.
-the utricular macula is disposed in the horizontal plane; it
responds maximally to tilting the head forward or backward.
-the saccular macula is disposed in the vertical plane; it responds
maximally to tilting the head to the side.
b. Hair cells
-are structurally similar to those of the cristae ampullares.



--------------------------------------- 100

Chapter 12 Vestibular System I 189
-are embedded in the gelatinous otolithic membrane, which con-
tains calcareous otolith crystals.
-are stimulated by the shearing effect of the otolithic membrane
during head movements.
-receive an efferent innervation from the vestibular nuclei of the
brainstem.
C. Fluids of the labyrinth
1. Perilymph
-resembles extracellular fluid and surrounds the membranous
labyrinth (in the perilymphatic space), —communicates with the
subarachnoid space via the perilymphatic
duct of the cochlear canaliculus.
-site of production and absorption is unknown.
2. Endolymph
—resembles intracellular fluid and is found within the membranous
labyrinth (endolymphatic space).
—is secreted by the stria vascularis of the cochlear duct, -
is thought to be absorbed by the endolymphatic sac.
III. Vestibular Pathways (Figure 12-2; see Figure 12-1)
A. Hair cells
-see II.
B. Bipolar neurons of the vestibular ganglion (see Figure 12-1)
—are located in the fundus of the internal auditory meatus.
-project, via their peripheral processes, to hair cells.
-project their central processes, as the vestibular nerve, to the
vestibular nuclei of the medulla and pons and, via the juxtaresti-
form body, to the flocculonodular lobe of the cerebellum (vestibulo-
cerebellum).
C. Vestibular nuclei (see Figures 9-4-9-6)
-include the inferior, medial, superior, and lateral nuclei.
1. Receive input from:
a. Bipolar neurons of the vestibular ganglion
b. Flocculonodular lobe and uvula of the cerebellum
Previous << 1 .. 75 76 77 78 79 80 < 81 > 82 83 84 85 86 87 .. 351 >> Next