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Osteology

Left temporal bone, inferior view; middle and inner ear cavities dissected

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Image #41-1
Bassett ImageDiagram Image
Legend Image
Osteology
Left temporal bone, inferior view; middle and inner ear cavities dissected
The petrous and tympanic parts of the bone have been ground away from below to expose the tympanic cavity (middle ear), which occupies the central area of the view, and the osseous labyrinth (inner ear), medial to the tympanic cavity. The cochlea has been opened parallel to the modiolus (6) to expose its basal, middle, and apical turns.
1 . Carotid canal
2 . Helicotrema
3 . Wall of modiolus
4 . Upper pointer: Scala vestibuli Lower pointer: Scala tympani
5 . Spiral canal of modiolus
6 . Base of modiolus
7 . Internal acoustic meatus (pointer on transverse crest)
8 . Lamina bony spiral
9 . Spherical recess of vestibule (rough white area in view is macula cribrosa superior)
10 . Upper pointer: Superior bony ampulla (deep in vestibule) Lower pointer: Eliptical recess of vestibule
11 . Opening of common crus
12 . Upper pointer: posterior bony ampulla Lower pointer: Posterior semicircular canal
13 . Mandibular fossa
14 . Semicanal of auditory tube
15 . Tensor tympani muscle
16 . Petrotympanic fissure (pointer indicates site of emergence of chorda tympani)
17 . Cut edge of tympanic part
18 . Cochleariform process
19 . Epitympanic recess (deep part of cavity)
20 . Position of oval window (obscured by promontorium)
21 . External acoustic meatus
22 . Prominence of facial canal
23 . Promontorium (note promontory sulcus for tympanic plexus)
24 . Round window (cut open)
25 . Pyramidal eminence
26 . Tympanic sinus
27 . Canal for stapedius muscle
28 . Facial canal