Chap. 9-Anatomy of Hearing (CHAPTER REVIEW)

Chapter Nine of Seikel, J. A., Drumright, D. G., Hudock, D. J. (2021). Anatomy and physiology for speech, language, and hearing. Sixth Edition. Plural Plus

“Energy Transducer”

(of the ear) converts acoustic energy into electrochemical energy

Pinna

(aka auricle) of the outer ear, collector of sound to be processed deeper. Structure provided by cartilaginous framework. Latin for FEATHER.

Helix

Forms curled margin of pinna, marking its most distal borders. Greek for COIL.

Auricular (Darwin’s) tubercle

Superior-posterior bulge on the helix.

Antihelix

Immediately anterior to the helix, fold of tissue marking entrance to the concha.

Scaphoid Fossa

Between helix and antihelix.

Crura Anthelicis

Produced by the antihelix bifurcating superiorly.

Cymba Conchae

Anterior extension of helix, marks anterior entrance to concha.

Cavum conchae

Deep portion of the concha

Concha (external auditory meatus)

Entrance to the ear canal

Tragus

Flap of epithelium-covered cartilage, may have covered the meatus entrance in early version of auditory mechanism

Tuberculum supratagicum

Superior to the tragus

Antitragus

Posterior and inferior to the tragus

Intertragic incisure

Region between tragus and antitragus

Lobule

Below the antitragus

Auricular cartilage

Unitary structure, covered with a layer of epithelial tissue invested with fine hairs, useful for keeping insects and dirt out of the ear canal.

External auditory meatus

7 mm diameter, 2.5 cm long from depth of concha.

Tympanic membrane (eardrum)

thin, oval, semi-transparent membrane that separates the outer ear from the middle ear.

Cerumen

Ear wax, along with hairs in the EAM, they trap insects and dirt, protecting the tympanic membrane. Secreted by glands into the ear canal.

Umbo

Most distal point of attachment of inner TM to the malleus in middle ear.

Cone of light

Inferior and anterior to the TM, Reflects the light of the audiologist’s otoscope.

Otitis externa

Inflammation of external ear skin. May result from bacterial infection after trauma, abrasion, or viral infection (herpes zoster virus) Very painful infection that can lead to facial paralysis or hearing loss when facial or vestibulocochlear nerves are involved.

Edema

Swelling caused by inflamed tissue

Auricular malformations

Arise from issues in embryological development

Deformations

Arise from effects of physical forces on the prenatal structures.

Chondrogenesis

Failure of cartilage to develop

Meatal Atresia

cartilage doesn’t develop, born without the external auditory meatus

Microtia

Small auricle

Polyotia

When parts of auricle are duplicated, sometimes leading person to develop a second tragus- may occur in hemifacial microsomia.

Preauricular Tags

Prominences that form prenatally anterior to the pinna

Cryptotia

Congenital absences or maldevelopment of upper portion of the ear

Anotia

Complete absence of pinna

Stahl’s ear

pointy, elfin-shaped ears.

Pars flaccida

“flaccid part” of the TM in the superior quadrant.

Anterior and posterior malleolar folds

the recess on either side of the pars flaccida

Tympanic sulcus

Groove in the temporal bone, incomplete in superior aspect to accommodate the anterior and posterior malleolar folds.

Cuticular Layer

Outer layer of the TM tissue, continuation of epithelial lining of EAM and pinna

Fibrous layer

intermediate layer of the TM tissue, composed of TWO layers

Superficial layer (of TM fibrous layer)

Composed of fibers that radiate out from handle of malleus to the periphery

Deep Layer (of TM fibrous layer)

Made up of circular fibers that are found mostly in the periphery of the membrane

Mucous layer

Inner layer of the TM, continuous with mucosa of middle ear

Ossicles

bones of the ear (malleus, incus, and stapes)

Ossicular chain

made of three articulated bones, provide means for transmission of acoustic energy striking on the TM to inner ear

Malleus

Largest of ossicles, provides point of attachment with TM

Manubrium

Handle of the malleus, long process, separated from the head by a thin neck

Anterior and lateral processes

Provide attachment for ligaments

Caput

Head, head of malleus protrudes into epitympanic recess of middle ear.

Incus

“The anvil” provides intermediate communicating link of ossicular chain.

Incus body

articulates with the head of the malleus through the malleolar facet, allowing long process of incus to be parallel with manubrium of malleus

Lenticular process

process of the incus where the stapes articulates

Stapes

“stirrup”, caput articulates with lenticular process of incus, and neck bifurcates to become the crura.

Bifurcate

to cause to DIVIDE into TWO branches or parts

Serous (secretory) otitis media

any condition where fluid accumulates in middle ear cavity

Auditory (pharyngotympanic) tube

allows oxygen into the middle ear space (aeration)

Tensor tympani

muscle, inserts into upper manubrium malli and pulls the malleus anteromedially.

Medial wall of middle ear cavity landmarks

oval window, round window, promontory of cochlea, and prominence of the facial nerve

Anterior wall

Houses entrance to auditory tube

Posterior wall

houses the prominence of the stapedial pyramid.

Stapedius muscle

inserts into posterior neck of stapes and pulls stapes posteriorly

Ligaments of ossicular chain

superior, anterior, and lateral of the malleus ligaments (SAL), and posterior and superior ligaments of incus (PS)

Inner ear

Houses sensors for balance (vestibular) and hearing (cochlea)

Vestibule

entrance to cochlea

Osseous labyrinth

(the snail) made up of entryway to the labyrinth, vestibule, semicircular canals, and osseous cochlear canal

Two incomplete chambers of the labyrinth

scala vestibuli and scala tympani

Osseous spiral lamina

incomplete bony shelf protruding from modiolus. divides the scala vestibuli and scala tympani

Round window

provides communication between scala tympani and middle ear space

Mediolus

latin for hub

Oval window

permits communication between the scala vestibuli and middle ear space

Cochlear aqueduct

connects the upper duct and the subarachnoid space

Crista

receptor organ for movement within vestibular mechanism

Membranous labyrinth

fluid filled sac, rests within the cavity of the osseous labyrinth, filled with endolymph. Houses the vestibular organ.

Ampulla

expanded region of the semicircular canals, contains crista ampullaris. In the vestibule lies the utricle and saccule.

Scala media

Made up of the membranous labyrinth of cochlea residing between the scala vestibuli and scala tympani

Reissner’s membrane

forms upper boundary of the scala media, and the basilar membrane forms the floor.

Organ of Corti

has four rows of hair cells resting on a bed of Deiter’s cells for support

Outer hair cells

separated from the inner hair cell row by the tunnel of Corti

Tunnel of corti

separates outer hair cells from inner hair row

Stereocilia

graces the upper surface of each hair cell, connected by tip links