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7 Cards in this Set
- Front
- Back
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INNER EAR
VESTIBULE |
1. The vestibule is the oval, middle part of the bony labyrinth located pos-
terior to the scala vestibuli and scala tympani and anterior to the semi- circular canals; it contains two rounded chambers of the membranous labyrinth, the utricle and saccule |
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INNER EAR
UTRICLE AND SACCULE |
2. The utricle and saccule are joined together by the utriculosaccular duct
from which the endolymphatic duct courses posteriorly within the ves- tibular aqueduct, a tiny canal in the petrous part of the temporal bone; distally, the endolymphatic duct emerges into the posterior cranial fossa on the posterior surface of the petrous part of the temporal bone as a dilatation called the endolymphatic sac |
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INNER EAR
SENSORY HAIR CELLS (w/in u/s) |
a. Sensory hair cells within the utricle and saccule sense gravity and
initiate reflex contraction of limb and trunk muscles in response to changes in the position of the head |
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INNER EAR
MENIERES DISEASE |
b. Clinical note: Meniere's disease is characterized by an increase in
pressure within the membranous labyrinth, which may damage its sensory hair cells; one form of treatment is to surgically incise the endolymphatic sac in the posterior cranial fossa to allow drainage of excess endolymph into the subarachnoid space |
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INNER EAR
FORAMINA W/IN MEDIAL WALL OF VESTIBULE |
3. Foramina within the medial wall of the vestibule transmit branches of
the vestibular division of the vestibulocochlear nerve to the internal acoustic meatus; its lateral wall is perforated by the oval window |
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INNER EAR
SEMICIR. CANALS & DUCTS |
1. Each of three tubular, archlike, semicircular canals contains a similarly
contoured semicircular duct; each semicircular canal and semicircular duct pair lies in a different plane and, each semicircular canal and duct is composed of two crura, one of which exhibits a terminal dilatation called an ampulla |
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INNER EAR
SEMICIR. CANALS & DUCTS -how do they open? |
2. The semicircular canals and semicircular ducts open into the vestibule
and utricle, respectively; the ampullae of the semicircular ducts containsensory hair cells that sense rotational movements of the head and ini- tiate reflex contraction of eye and neck muscles |
