Ear Anatomy and Physiology

• Smell receptors are specialized cells that detect odors.
• Taste receptors are cells that identify different taste modalities.

Afferent Pathways

• Nerve pathways transmit sensory information.

Auricle

• The auricle, also known as the pinna, is the outer part of the ear.

External Acoustic Meatus

• The external acoustic meatus is the auditory canal leading to the eardrum.

Tympanic Membrane

• The tympanic membrane, also known as the eardrum, vibrates with sound waves.

Auditory Ossicles

• The auditory ossicles are three small bones in the middle ear.

Malleus

• The malleus is the first auditory ossicle, also known as the hammer.

Incus

• The incus is the second auditory ossicle, also known as the anvil.

Stapes

• The stapes is the third auditory ossicle, also known as the stirrup.

Pharyngotympanic Tube

• The pharyngotympanic tube links the middle ear to the nasopharynx, which allows for pressure equalization.

Bony Labyrinth

• The bony labyrinth consists of cavities in the temporal bone filled with perilymph.

Membranous Labyrinth

• The membranous labyrinth consists of ducts within the bony labyrinth filled with endolymph.

Cochlea

• The cochlea is a spiral structure containing the organ of Corti.

Organ of Corti

• The organ of Corti is the receptor organ for hearing, and is located in the cochlea.

Basilar Membrane

• The basilar membrane is a membrane in cochlea that is critical for sound reception.

Scala Vestibuli

• The scala vestibuli is the upper chamber of the cochlea next to the oval window.

Scala Tympani

• The scala tympani is the lower chamber of the cochlea that terminates at the round window.

Cochlear Duct

• The cochlear duct is the middle chamber of the cochlea and houses the organ of Corti.

Endolymph

• Endolymph is a fluid in the membranous labyrinth, and is rich in potassium.

Perilymph

• Perilymph is a fluid in the bony labyrinth, and is similar to cerebrospinal fluid.

Sound Frequency

• Sound frequency is the number of sound waves per second, and is measured in Hz.

Sound Amplitude

• Sound amplitude is the height of sound waves, and is measured in decibels (dB).

Resonance of Basilar Membrane

• Specific frequency response occurs on the basilar membrane.

Helicotrema

• The helicotrema is the apex of cochlea where the scala vestibuli and tympani meet.

Auditory Tube

• The auditory tube, also known as the Eustachian tube, equalizes pressure in the ear.

Cochlear Branch

• The cochlear branch is the part of vestibulocochlear nerve for hearing.

Vestibular Branch

• The vestibular branch is the part of vestibulocochlear nerve for balance.

Semicircular Canals

• Semicircular canals are structures in inner ear that are there for balance and spatial orientation.

Utricle

• The utricle is the part of vestibular system that detects horizontal movements.

Saccule

• The saccule is the part of vestibular system that detects vertical movements.

Ampulla

• The ampulla is the enlarged area of semicircular canals containing sensory cells.

Tectorial Membrane

• The tectorial membrane is the membrane above hair cells in the cochlea.

Sound Conduction Pathway

• The sound conduction pathway is the route sound takes from the outer ear to inner ear.

Pressure Wave

• A pressure wave is a wave created by sound vibrations in fluid.
• A vibrating object is a source of sound that creates sound waves.
• The cochlear duct contains hair cells for sound detection.
• The temporal bone houses the structures of the inner ear.

External Ear

• The external ear includes the auricle and external acoustic meatus.

Middle Ear

• The middle ear is an Air-filled cavity containing auditory ossicles.

Inner Ear

• The inner ear contains cochlea and vestibular structures.
• Sound intensity is the perceived loudness of sound, and is related to amplitude.

Decibels (dB)

• Decibels (dB) are the unit to measure sound intensity or loudness.
• Hertz (Hz) are the unit to measure frequency of sound waves.

Outer Ear

• The outer ear collects sound waves and directs them inward.

Middle Ear

• The middle ear amplifies sound vibrations.

Inner Ear

• The inner ear contains structures for hearing and balance.
• The scala vestibuli contains perilymph, and is part of cochlea.
• The cochlear duct contains endolymph, and is involved in sound transduction.
• The scala tympani contains perilymph, and is part of cochlea.
• The tectorial membrane sits above hair cells and involved in sound detection.
• The spiral organ, also known as the organ of Corti, contains hair cells.
• The basilar membrane vibrates in response to sound, and supports hair cells.
• Stereocilia are hair-like projections on hair cells that detect sound.
• Inner hair cells are sensory cells that send auditory signals to the brain.
• Outer hair cells amplify sound vibrations, and adjust tectorial membrane tension.

Sound Transduction

• Sound transduction is the conversion of sound waves into electrical signals.
• Frequency perception is determined by hair cell position along basilar membrane.
• Volume perception is related to amplitude of sound wave vibrations.
• Auditory localization is the ability to determine sound source location.
• The vestibule is the central cavity of the bony labyrinth, and contains maculae.
• The saccule monitors vertical head position and acceleration.
• The utricle monitors horizontal head position and acceleration.
• Semicircular canals detect rotational movements, and contain cristae ampullares.
• Crista ampullaris is the equilibrium receptor in semicircular canals.
• Maculae are equilibrium receptors in saccule and utricle.
• Endolymph is a fluid in membranous labyrinth that is involved in balance.
• Perilymph is a fluid in bony labyrinth that surrounds membranous structures.
• Tip links connect stereocilia and are essential for hair cell function.
• Depolarization is increase in hair cell membrane potential.
• Hyperpolarization is decrease in hair cell membrane potential.
• Action potential frequency is rate of nerve impulses generated by hair cells.
• Neurotransmitter release is triggered by hair cell depolarization, which signals neurons.
• Angular acceleration is detected by cristae ampullares in semicircular canals.
• Linear acceleration is monitored by saccule and utricle maculae.
• Hair cell neurotransmitter changes with head movement, which affects action potentials.
• The cupula is the gelatinous structure in ampulla and is involved in balance.
• Inertia causes endolymph lag during head rotation.
• The cochlear branch is part of vestibulocochlear nerve and transmits auditory signals.
• First-order auditory neuron is initial neuron in auditory pathway.
• Graded potentials are changes in membrane potential that lead to action potentials.
• Tension of tectorial membrane is altered by outer hair cells, which enhances hearing.
• Hearing sensitivity is the ability to detect quiet sounds, and is improved by outer hair cells.
• Head position monitoring is performed by vestibule and is essential for balance.
• Complex movements coordination involves information from vestibular and visual systems.
• The Sound conduction pathway is the route sound takes to reach inner ear fluids. Basilar membrane deflection is caused by sound waves and triggers hair cell response.

Sound Transduction

• Sound Transduction is the process by which sound waves are converted into electrical signals in the auditory system.
• Pitch differentiation regards the ability to perceive different frequencies of sound.
• Loudness differentiation regards the ability to perceive the intensity of sound.
• Localization of sound regards the ability to determine the origin of a sound in the environment.
• Balance organs are structures in the semicircular canals and vestibule that help maintain equilibrium.
• Functions of blood include delivery of oxygen and nutrients, transport of metabolic wastes for elimination, and transport of hormones.
• Thermoregulation is the function of blood that includes maintaining body temperature.

pH Maintenance

• pH maintenance is the function of blood that includes maintaining pH balance in the body.
• Fluid balance is the function of blood that includes maintaining fluid levels in the body.
• Hemostasis is the function of blood that includes preventing blood loss.
• Immune response is the function of blood that includes fighting infections.
• The composition of blood means it is composed of living cells suspended in a fluid called blood plasma.
• Blood plasma is the liquid component of blood that makes up approximately 55% of its volume.

Explore the anatomy and physiology of the ear. Learn about smell and taste receptors and their functions. Discover the components from the auricle to the bony labyrinth.