Anatomy of the Ear Flashcards

Vocabulary flashcards covering the key structures, measurements, and anatomy of the external, middle, and inner ear based on the lecture notes.

Temporal bone

The most complicated bone in the human body, forming part of the lateral skull base.

Pinna (auricle)

The outer ear structure made up of a framework of a single piece of yellow elastic cartilage covered with skin, except for its lobule.

Cartilaginous part of EAC

The outer $8\,\text{mm}$ ($\frac{1}{3}$) of the external auditory canal, lined with thick skin containing ceruminous and pilosebaceous glands that secrete earwax.

Bony part of EAC

The inner $16\,\text{mm}$ ($\frac{2}{3}$) of the external auditory canal, lined with thin skin continuous over the tympanic membrane and devoid of hair and ceruminous glands.

Isthmus

The narrow bone-cartilaginous junction of the external auditory canal.

Tympanic membrane

A conical-shaped membrane separating the external and middle ear, measuring about $1\,\text{cm}$ in diameter with an area of about $85\,\text{mm}^2$ ($55\,\text{mm}^2$ physiologically effective).

Pars tensa

The larger, tense portion of the tympanic membrane whose periphery is thickened by a fibrocartilaginous ring called the annulus tympanicus.

Pars flaccida (Shrapnell's membrane)

The upper, flaccid region of the tympanic membrane situated above the lateral process of the malleus between the Notch of Rivinus and the anterior and posterior malleal folds.

Notch of Rivinus

A small deficiency in the tympanic sulcus situated at the superior aspect of the tympanic membrane.

Middle ear cleft

An anatomical region comprising the middle ear cavity (tympanic cavity), mastoid air cells, and Eustachian tube.

Eustachian tube

A $36\,\text{mm}$ tube ($12\,\text{mm}$ bony, $24\,\text{mm}$ fibrocartilaginous) connecting the nasopharynx to the tympanic cavity, lined by pseudostratified ciliated columnar epithelium.

Epitympanum (attic)

The uppermost portion of the middle ear cavity lying above the level of the malleal folds.

Mesotympanum

The middle portion of the middle ear cavity lying directly opposite the pars tensa.

Hypotympanum

The lower portion of the middle ear cavity lying below the level of the pars tensa.

Tegmen tympani

A thin plate of bone forming the roof of the middle ear that separates the tympanic cavity from the middle cranial fossa.

Promontory

A rounded bulge on the medial wall of the middle ear produced by the basal coil of the cochlea.

Process cochleariformis

A hook-like bony projection situated just anterior to the oval window on the medial wall of the middle ear, around which the tendon of the tensor tympani muscle turns.

Pyramid

A bony projection on the posterior wall of the middle ear through whose summit the tendon of the stapedius muscle emerges.

Aditus

An opening located above the pyramid in the posterior wall of the middle ear through which the attic communicates with the mastoid antrum.

Scutum

The bony outer attic wall forming part of the lateral wall of the middle ear.

Modiolus

The central bony pillar around which the bony cochlea coils $2.5$ to $2.75$ turns.

Helicotrema

The opening at the apex of the cochlea through which the scala vestibuli and scala tympani communicate with each other.

Aqueduct of cochlea

A channel connecting the scala tympani to the subarachnoid space.

Organ of Corti

The sensory organ of hearing supported by the basilar membrane within the cochlear duct (scala media).

Macula

The sensory epithelium located within the utricle and saccule responsible for sensing linear acceleration and deceleration.

Crista ampullaris

The neuroepithelium located in the ampullated end of each semicircular duct responsible for sensing angular acceleration.