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5 Cards in this Set
- Front
- Back
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TYMPANIC CAVITY
POSTERIOR WALL -"ADITUS & ANTRUM" -"PYRAMIDAL EMINENCE" |
5. Posterior wall
a. An irregular aperture, the aditus ad antrum, is located superiorly on the posterior wall; it is continuous posteriorly with an expanded chamber, the mastoid antrum, which, in turn, is continuous with the mastoid air cells b. The pyramidal eminence, a hollow, volcanolike projection, lies infe- rior to the aditus ad antrum |
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TYMPANIC CAVITY
MEDIAL WALL PROMONTORY -describe -within mucosal covering... |
6. Medial wall
a. Promontory 1. Round bulge located centrally on the medial wall; produced by the basal turn of the cochlea 2. Within its mucosal covering lies a nerve network, the tympanic plexus, which is formed by the caroticotympanic nerves and the tympanic branch of the glossopharyngeal nerve; the tympanic branch of the glossopharyngeal nerve is composed ofpregangli- onic parasympathetic fibers from the inferior salivatory nucleus in the brainstem as well as general sensory fibers |
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TYMPANIC CAVITY
MEDIAL WALL PROMONTORY -TYMPANIC PLEXUS |
6. Medial wall
a. Promontory 3. The tympanic plexus gives rise to the lesser petrosal nerve, which traverses a small canal near the semicanal for the tensor tympani, emerges into the middle cranial fossa through the hiatus for the lesser petrosal nerve, continues anteriorly in the sulcus for the lesser petrosal nerve, and exits the skull through foramen ovale to reach the subjacent otic ganglion; preganglionic parasympa- thetic fibers within the lesser petrosal nerve synapse in the otic ganglion (postganglionic sympathetic fibers from the carotico- tympanic nerves pass through without synapse) and postgangli- onic parasympathetic secretomotor fibers from the otic ganglion are distributed to the parotid gland via the auriculotemporal and facial nerves |
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TYMPANIC CAVITY
MEDIAL WALL -"ROUND WINDOW" |
6. Medial wall
b. Round window (fenestra cochleae): round opening posteroinferior to the promontory; it is closed in life by the secondary tympanic mem- brane, which undergoes compensatory movements opposite those of the pistonlike stapes |
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TYMPANIC CAVITY
MEDIAL WALL -"OVAL WINDOW" |
c. Oval window (fenestra vestibuli): oval opening superior to the prom-ontory; it is closed in life by the base of the stapes and annular liga-
ment |
