audio week 2 (ch. 3 & 11)

Comprehensive practice flashcards detailing the anatomy, physiology, and pathology of the peripheral auditory, central auditory, and vestibular systems.

Auricle

The visible external portion of the auditory system composed of cartilage covered by skin, including anatomical structures such as the pinna, helix, lobule/lobe, tragus, and concha.

External Auditory Canal

An S-shaped tube that carries sound from the pinna to the tympanic membrane, consisting of an outer two-thirds made of cartilage and an inner one-third made of bone.

Cerumen

A protective ear canal secretion produced by sebaceous and ceruminous glands that catches debris, deters insects, and minimizes bacterial and fungal growth.

Tympanic Membrane

A structure consisting of three layers of tissue that separates the external ear canal from the middle ear space and displays a cone of light when illuminated.

Auditory Ossicles

The tiniest bones in the human body—the malleus, incus, and stapes—that form a chain connecting the tympanic membrane to the inner ear.

Impedance Matching

The process by which the middle ear increases sound pressure to overcome the air-to-fluid energy mismatch via the surface area ratio of the tympanic membrane to stapes footplate, the lever action of the ossicles, and the membrane's shape.

Inner Hair Cells

Sensory cells of the cochlea whose stereocilia depolarize upon potassium ion release following fluid displacement, receiving direct communication from $95\%$ of afferent auditory nerve fibers.

Outer Hair Cells

Cochlear sensory hair cells that connect with $5\%$ of afferent auditory nerve fibers and play an essential role in mechanical amplification.

Tonotopic Organization

The spatial arrangement within the cochlea whereby high-pitched sounds activate hair cells at the basal end and low-pitched sounds activate hair cells toward the apex.

Afferent Auditory Pathways

Neural pathways that transmit sensory information upward from the ear to the brain, with the vast majority connecting directly to inner hair cells.

Efferent Auditory Pathways

Descending neural pathways that originate in the lowest region of the brain and travel through the internal auditory canal downward into the cochlea.

Eighth Cranial Nerve

The auditory/vestibular nerve (cranial nerve VIII) that transmits auditory and balance signals from the inner ear to the brainstem, with $10\text{ to }20$ afferent fibers synapsing per inner hair cell.

Internal Auditory Canal

A narrow passageway through the petrous temporal bone that provides a passage shared by the auditory/vestibular nerve and the facial nerve (CN VII).

Pons

A region of the brainstem containing important auditory centers and pathways where auditory nerve fibers enter near the cerebellar peduncles.

Heschl's Gyrus

The primary auditory cortex located within the cerebrum where ascending auditory information from lower brainstem pathways first arrives.

Semicircular Canals

Three fluid-filled loops in the vestibular system containing hair cells inside ampullae that transduce angular head motion across all spatial planes.

Otolith Organs

The utricle and saccule, which contain otoliths and hair cells that respond to linear acceleration and gravitational changes in body orientation.

Collapsing Ear Canals

A condition most common in infants and the elderly where supra-aural headphones cause canal closure, producing an artificial high-frequency conductive hearing loss that is resolved using insert earphones.

Preauricular Pit

A small congenital depression in the skin located in front of the tragus, frequently observed in cases of syndromic hearing loss.

Preauricular Tag

One or more small fleshy stalks consisting of skin and underlying tissue situated directly in front of the earlobe.

Microtia

A congenital malformation presenting as an underdeveloped, abnormally formed, or completely absent external ear, resulting in conductive hearing loss.

Atresia

The congenital absence or complete closure of the external auditory canal, frequently accompanying microtia and causing conductive hearing loss while inner ear function remains intact.

Otitis Externa

Inflammation of the outer ear canal typically resulting from bacterial, viral, or fungal infections, which does not always impair hearing.

Osteomas

Benign bony stalks of growth located in the outer, cartilaginous portion of the external ear canal.

Exostoses

Broad-based bony growths that develop deep within the osseous portion of the ear canal near the tympanic membrane.

Eustachian Tube Dysfunction

Impaired middle ear aeration and pressure regulation—common in children due to developing craniofacial anatomy—often characterized by type C tympanograms and conductive hearing loss.

Patulous Eustachian Tube

A condition in which the Eustachian tube remains persistently open, causing patients to report whooshing sensations and autophony; frequently linked to recent weight loss.

Otitis Media with Effusion

The accumulation of fluid within the middle ear space in the absence of acute infection symptoms, commonly developing after an episode of acute otitis media.

Cholesteatoma

An abnormal, noncancerous skin-lined cyst or growth located in the middle ear space or mastoid that can be congenital or acquired and requires surgical management.

Otosclerosis

A progressive, genetically influenced bone disease where vascular spongy bone replaces normal bone and hardens, resulting in ossicular chain fixation—most commonly at the stapes footplate.

Ossicular Chain Disarticulation

A mechanical break or interruption along the ossicular chain connecting the tympanic membrane to the cochlea, frequently caused by head trauma or temporal bone fracture.

Autoimmune Inner Ear Disease

An inner ear pathology where circulating antibodies damage inner ear structures, typically managed with prompt steroid therapy.

Presbycusis

Gradual, age-related sensorineural hearing loss occurring bilaterally that primarily affects high frequencies and creates significant difficulty understanding speech in noise.

Noise-Induced Hearing Loss

Permanent sensorineural hearing impairment caused by loud sound exposure, characterized by a classic audiometric notch or dip at $4000\,\text{Hz}$.

Meniere's Disease

An inner ear condition associated with excessive endolymph fluid buildup, clinically characterized by episodic vertigo spells, roaring tinnitus, aural fullness, and fluctuating low-frequency sensorineural hearing loss.

Superior Semicircular Canal Dehiscence

An abnormal bony defect creating a third mobile window above the superior semicircular canal, resulting in autophony (hearing one's own eye movements or footsteps) and sound- or pressure-induced vertigo.

Barotrauma

Traumatic injury to the middle or inner ear caused by an inability to equalize pressure during rapid ambient pressure changes, such as during diving or air travel.