Download (direct link):
-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
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.
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
C. Fluids of the labyrinth
-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.
—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
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-
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