Histology of the Inner Ear

Histology of the Inner Ear

Follow protocol Notebook Illustrations

Above left are the three ossicles photographed with a dime to show their relative size. The left most bone is the malleus (hammer) which is attached directly to the typmanic membrane. It transmits vibrations to the incus (anvil) which in turn transmits vibrations to the right most bone, the stapes (stirrup). The flat end of the stapes fits into the oval window of the cochlea which then transmits vibrations into the cochlea along the scala vestibuli.

Examine the following two slides, note the features in common and the differentiating features. Illustrate each at the noted power to take up a page. Compare with the illustrations in di Fiore’s Atlas of Normal Human Histology, 9th Ed.

Slide 9: Ear, cochlea., guinea pig, (71571) Two views, and overview, and a detail: (see MF 9th, page 347, fig. 19-7 & fig 19-9)

cochlear_nerve_40x_P2182170
Cochlea cross section, Overview at 40x:
helicotrema
scala vestibuli (from oval window)
vestibular membrane
scala tympani (to round window)
basilar membrane
cochlear duct
organ of corti
osseus labyrinth (bony case)
spiral lamina (bony core)
spiral ganglion
cochlear nerve (visible in some)
Here is a labeled view of the 40x view including the cochlear nerve.
cochlea_P2171518md

Cochlea, showing helicotrema and an intact set of membranes:
vestibular membrane
basilar membrane

cochlea_loop_P2171519
cross section through cochlear loop

Cochlear duct detail, 100x: (MF 9th, page 347, fig 19-8.)
organ of corti
tectorial membrane
hair cells (orange at tips)
internal spiral sulcus
basilar membrane
spiral ligament
cochlear duct Here is the image labeled .
endolymph
vestibular membrane
scala vestibuli
scala tympani
perilymph
osseus spiral lamina
spiral ganglion

Organ_of_Corti_P2171518

Organ of Corti
organ of corti
tectorial membrane
hair cells (orange at tips)
internal spiral sulcus
basilar membrane
spiral ligament
cochlear duct
endolymph
vestibular membrane
osseus spiral lamina

Slide 11. Crista ampullaris (H 1697)

The semicircular canals detect angular or rotational acceleration. This is a cross section through an ampulla of a semicircular duct. (There is no illustration in di Fiore.)
crista_ampullaris_40x_PC271523

Semicircular Canal, 40x, cross section
Note boney labyrinth surrounding the canal

crista_ampullaris_100x_PC271524

Crista Ampullaris, 100x:
crista ampullaris (ridge-like structure)
receptor epithelium (hair cells on crista)
cupola (gelatinous mass on top of the crista)
ampulla of semicircular duct
endolymph (fills the chamber)
membranous labyrinth Here is a labeled view of the crista ampullaris.

crista_ampullaris_200x_PC271525
Crista Ampullaris, 400x
Hair cells can be made out.

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