Dissection of left ear from posterior aspect

Relation of facial nerve and stapedius muscle to tympanic cavity and labyrinth

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Image #62-5
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Dissection of left ear from posterior aspect
Relation of facial nerve and stapedius muscle to tympanic cavity and labyrinth
The semicircular canals have been cut away and the vestibule opened to show the footplate of the stapes (4) lying in the fenestra vestibuli. The facial nerve (7), together with branches of the stylomastoid artery and veins, is visible within the opened facial canal. The stapedius muscle and its nerve have been dissected and are illustrated to the drawing at 11. The muscle appears light in the view because of tendinous fibres on its surface. The tympanic branch (22) of the glossopharyngeal nerve (25) can be traced into the posterior part of the tympanic cavity.
1 . Greater superficial petrosal nerve
2 . Geniculate ganglion
3 . Vestibule
4 . Base of stapes in fenestra vestibuli
5 . Capitulum of malleus
6 . Body of incus
7 . Facial nerve (VII)
8 . Upper pointer: Posterior crus of stapes Lower pointer: Capitulum of stapes
9 . Pyramidal eminence
10 . Upper pointer: Manubrium of malleus Lower pointer: Tympanic membrane
11 . Stapedius nerve and muscle
12 . Tympanic sinus
13 . Mastoid cell
14 . Position of stylomastoid foramen
15 . Alar fascia
16 . Upper and lower divisions of vestibulocochlear nerve (VIII) (vestibular part)
17 . Vestibulocochlear nerve (VIII) (cochlear part)
18 . Internal acoustic meatus
19 . Base of modiolus
20 . Veins surrounding internal carotid artery within carotid canal
21 . Osseous spiral lamina in basal turn of cochlea
22 . Tympanic nerve
23 . Mastoid cell
24 . Veins within petro-occipital fissure
25 . Glossopharyngeal nerve (IX)
26 . Vagus nerve (X)
27 . Anastomotic branch glossopharyngeal nerve with auricular brancjes of vagus nerve