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Questions and Answers
Which organ is responsible for static equilibrium?
Which organ is responsible for static equilibrium?
Dynamic equilibrium occurs only when the head is motionless.
Dynamic equilibrium occurs only when the head is motionless.
False (B)
What are the two saclike structures involved in static equilibrium?
What are the two saclike structures involved in static equilibrium?
Utricle and saccule
The grains of calcium carbonate embedded in the gelatinous mass are called ______.
The grains of calcium carbonate embedded in the gelatinous mass are called ______.
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Match the following structures with their functions:
Match the following structures with their functions:
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What initiates the impulse that travels through the vestibular branch of the vestibulocochlear nerve?
What initiates the impulse that travels through the vestibular branch of the vestibulocochlear nerve?
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The crista ampularis contains hair cells and supporting cells that are responsible for sensing dynamic equilibrium.
The crista ampularis contains hair cells and supporting cells that are responsible for sensing dynamic equilibrium.
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Where do most axons from the vestibular branch synapse?
Where do most axons from the vestibular branch synapse?
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When the head moves rapidly, the ______ remain stationary while the head moves.
When the head moves rapidly, the ______ remain stationary while the head moves.
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What is the role of the vestibulocochlear nerve in equilibrium?
What is the role of the vestibulocochlear nerve in equilibrium?
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What part of the ear is primarily responsible for amplifying sound vibrations?
What part of the ear is primarily responsible for amplifying sound vibrations?
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The cochlea is involved in equilibrium.
The cochlea is involved in equilibrium.
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What is the function of the tympanic membrane?
What is the function of the tympanic membrane?
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The ______ connects the middle ear to the throat and helps equalize air pressure.
The ______ connects the middle ear to the throat and helps equalize air pressure.
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Match the following components of the ear with their primary functions:
Match the following components of the ear with their primary functions:
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What fluid is found in the membranous labyrinth?
What fluid is found in the membranous labyrinth?
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Hearing receptors in the ear are classified as chemoreceptors.
Hearing receptors in the ear are classified as chemoreceptors.
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What are the names of the three auditory ossicles?
What are the names of the three auditory ossicles?
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The ______ is a disorder of the inner ear that can affect hearing and balance due to increased pressure.
The ______ is a disorder of the inner ear that can affect hearing and balance due to increased pressure.
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Match the ear parts with their descriptions:
Match the ear parts with their descriptions:
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What structure prevents foreign objects from reaching the eardrum?
What structure prevents foreign objects from reaching the eardrum?
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The external auditory canal is a straight tube that leads to the tympanic membrane.
The external auditory canal is a straight tube that leads to the tympanic membrane.
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What action occurs when the hair cells in the organ of Corti bend?
What action occurs when the hair cells in the organ of Corti bend?
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The ______ is known for being the connecting point between the middle ear and the inner ear.
The ______ is known for being the connecting point between the middle ear and the inner ear.
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Which part of the ear contains fluid-filled chambers responsible for balance?
Which part of the ear contains fluid-filled chambers responsible for balance?
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Flashcards
What are the two components of the sense of equilibrium?
What are the two components of the sense of equilibrium?
The sense of equilibrium is maintained by the combination of two sensory systems: static equilibrium and dynamic equilibrium.
What is static equilibrium?
What is static equilibrium?
Static equilibrium is the sense of the head's position relative to gravity when the head is stationary.
What is dynamic equilibrium?
What is dynamic equilibrium?
Dynamic equilibrium is the sense of the head's movement in a rotational or angular direction.
Where is the organ of static equilibrium located?
Where is the organ of static equilibrium located?
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What is the macula composed of?
What is the macula composed of?
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What are otoliths and where are they located?
What are otoliths and where are they located?
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How do otoliths and the gelatinous mass affect hair cells?
How do otoliths and the gelatinous mass affect hair cells?
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How do hair cell movements translate into nerve impulses?
How do hair cell movements translate into nerve impulses?
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What is dynamic equilibrium and where is its organ located?
What is dynamic equilibrium and where is its organ located?
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How is the crista ampullaris structured?
How is the crista ampullaris structured?
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Auricle (Pinna)
Auricle (Pinna)
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External Auditory Canal
External Auditory Canal
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Tympanic Membrane (Eardrum)
Tympanic Membrane (Eardrum)
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Middle Ear (Tympanic Cavity)
Middle Ear (Tympanic Cavity)
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Auditory Ossicles
Auditory Ossicles
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Eustachian Tube
Eustachian Tube
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Myringitis
Myringitis
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Otitis Externa
Otitis Externa
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Bony Labyrinth
Bony Labyrinth
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Endolymph
Endolymph
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Perilymph
Perilymph
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Cochlea
Cochlea
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Cochlear Duct
Cochlear Duct
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Basilar Membrane
Basilar Membrane
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Organ of Corti (Spiral Organ)
Organ of Corti (Spiral Organ)
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Study Notes
Anatomy and Physiology 2 - The Special Sense (Ear)
- The ear is the organ of hearing and equilibrium.
- Receptors for hearing are mechanoreceptors.
- The ear has three parts: external ear, middle ear, and inner ear.
Learning Objectives
- Describe the structure and function of the outer, middle, and inner ear.
- Explain the physiology of hearing.
- Describe the auditory pathway.
- Describe the physiology of equilibrium.
Introduction (Ear)
- The external/outer ear collects and channels sound waves.
- The middle ear/tympanic cavity amplifies sound vibrations using a bony system.
- The internal/inner ear generates action potentials to transmit sound and balance information to the brain.
The External Ear
- Consists of the auricle (pinna) and external auditory canal.
- The auricle (pinna) is the fleshy part that collects and directs sound waves to the auditory meatus.
- The external auditory canal is an 'S' shaped tube that channels sound waves to the tympanic membrane (eardrum).
- Contains ceruminous glands that secrete earwax (cerumen).
- Hair and cerumen prevent foreign objects from reaching the eardrum.
- The external ear ends at the tympanic membrane.
The Middle Ear
- An air-filled cavity in the temporal bone.
- Contains the auditory ossicles (malleus, incus, and stapes).
- Has an opening to the Eustachian tube.
- The oval and round windows connect the middle ear to the inner ear.
Middle Ear (cont.)
- Auditory ossicles transmit sound vibrations from the tympanic membrane to the oval window of the inner ear.
- Skeletal muscles control the movement of ossicles to prevent damage from loud noises.
Middle Ear (cont.2)
- The tympanic membrane is a thin, semi-transparent partition between the external auditory canal and the middle ear.
- It separates the outer ear from the middle ear cavity.
- It converts sound waves into vibrations.
Middle Ear (cont.3)
- The Eustachian tube connects the middle ear to the throat.
- It equalizes air pressure between the outside air and the middle ear cavity, necessary for normal hearing.
- Throat infections can spread to the middle ear through the Eustachian tube.
Middle Ear (Clinical Application)
- Myringitis - inflammation of the eardrum
- Otitis externa (swimmer's ear) - dermatitis of the outer ear (can be infectious or non-infectious).
The Internal Ear
- Consists of the bony labyrinth and membranous labyrinth.
- Bony labyrinth is a series of interconnecting chambers in the temporal bone.
- Membranous labyrinth is located inside the bony labyrinth.
Internal Ear (cont.)
- Endolymph fills the membranous labyrinth.
- Perilymph fills the space between the bony and membranous labyrinths.
- Divided into the vestibule, cochlea, and semicircular canals.
Internal Ear (cont.2)
- Vestibule and semicircular canals are involved in balance.
- The cochlea is involved in hearing.
Internal Ear (cont.3)
- The cochlea is the coil portion of the bony labyrinth.
- It functions in sound wave transduction.
- The cochlea has three regions: scala vestibuli, scala media (cochlear duct), and scala tympani.
- All three regions are filled with perilymph and endolymph.
Internal Ear (cont.4)
- The cochlear duct is part of the membranous labyrinth, triangular in shape.
- Contains supporting cells and specialized cochlear hair cells.
- Cochlear hair cells contain auditory receptors.
Internal Ear (cont.5)
- Organ of Corti (spiral organ) contains receptors for sound.
- Consists of supporting cells and hair cells.
- Hair cells form synapses with sensory and motor neurons in the cochlear branch of the vestibulocochlear (VIII) nerve.
Internal Ear (Clinical Application)
- Meniere's disease is a disorder of the inner ear affecting hearing and balance, possibly due to increased pressure in the cochlea and semicircular canals (extra endolymph).
- Episodes of vertigo and tinnitus can be symptoms
Physiology of Hearing
- Sound waves enter the external auditory meatus.
- Sound waves strike the tympanic membrane, causing it to vibrate back and forth.
- The vibration conducts through the ossicles (malleus → incus → stapes).
Physiology of Hearing (cont.)
- The stapes moves back and forth, pushing the membrane of the oval window in and out.
- Movement of the oval window membrane starts oscillations in the perilymph.
- Oscillations in the perilymph cause vibrations in the vestibular and basilar membranes.
- When the basilar membrane moves, the hair cells in the organ of Corti rub against the tectorial membrane and bend.
Physiology of Hearing (cont.2)
- Bending the hairs on the hair cells stimulates the formation of impulses.
- Impulses are transmitted to the auditory cortex of the temporal lobe on the cochlear branch of the cranial nerve VIII (vestibulocochlear nerve).
Recap – Mechanism of Hearing
- Sound waves enter the external auditory meatus.
- The auricle captures sound waves.
- The auditory canal channels the waves.
- The eardrum vibrates.
- Ossicles vibrate.
- Liquid in cochlea vibrates.
- Oval window vibrates.
- Auditory nerve carries the impulse to the brain.
Auditory Pathway
- Sensory neurons in the cochlear branch of the vestibulocochlear (VIII) nerve terminate in the medulla oblongata on the same side of the brain.
- Axons ascend to the midbrain, then the thalamus, and finally to the auditory cortex of the temporal lobe.
Sense of Equilibrium
- Equilibrium is the combination of static and dynamic equilibrium.
- Static equilibrium involves evaluating the head's position relative to gravity when motionless.
- Dynamic equilibrium occurs when the head is moving, such as in rotational or angular directions.
Static Equilibrium
- The organ that detects static equilibrium is located in the vestibule of the bony labyrinth of the inner ear.
- Labyrinth in the vestibule is divided into two saclike structures – utricle and saccule.
- Utricle and saccule contain macula.
- Macula is the organ of equilibrium composed of sensory hair cells and supporting cells.
- Protrusions of hair cells consist of a gelatinous mass.
Static Equilibrium (cont.)
- Otoliths are grains of calcium carbonate embedded in the gelatinous mass.
- When the head is upright, the hairs are straight.
- Tilting or bending the head makes the otoliths and gelatinous mass move and bend the hair cells.
- This action initiates impulses that travel along the vestibular branch of the vestibulocochlear nerve.
Dynamic Equilibrium
- Dynamic equilibrium involves maintaining balance during sudden movements.
- Sensory receptors are located in the crista ampularis.
- Crista is an elevation in the semicircular canals.
- Hair cells (sensory receptors) and supporting cells are present in the crista.
Dynamic Equilibrium (cont.)
- Cupula is a gelatinous mass that covers the crista.
- When the head moves rapidly, the semicircular canals and the head move, but the endolymph stays stationary.
- The fluids push against the cupula, tilting it.
- Tilting the cupula causes hairs on the hair cells to bend, triggering a sensory impulse.
Dynamic Equilibrium (cont.2)
- The vestibulocochlear nerve interprets the information and sends motor impulses to maintain balance.
- Impulses are transmitted to the CNS through the vestibular branch of the nerve
Equilibrium Pathway
- Nerve impulses travel up the vestibular branch of CN VIII.
- Axons synapse in the medulla and pons (major integrating centers for equilibrium).
- These centers also receive input from the eyes and proprioceptors.
- Ascending neurons continue to the primary auditory area in the parietal lobe to give us conscious awareness of the position and movements of the head and limbs.
Equilibrium Pathway (cont.)
- Hair cells from utricle, saccule and semicircular ducts stimulate the vestibular branch of the vestibulocochlear nerve.
- Nerve signals travel to the brainstem, cerebellum, and thalamus.
- Signals then reach the cerebral cortex.
Recap/Quiz
- What structures convert sound waves to vibrations? Tympanic membrane
- What structures convert vibrations to action potentials? Organ of Corti
- What structures carry action potentials caused by sound transduction? Vestibulocochlear nerve
- What structure collects and directs sound waves to move the tympanic membrane? Auricle/pinna
- What structures prevent damage by excessively loud noises? Auditory ossicles
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Description
Explore the anatomy and physiology of the ear in this quiz. Learn about the structure of the outer, middle, and inner ear, as well as the physiology of hearing and equilibrium. Test your understanding of how sound is processed and balanced in the auditory system.
