Special Senses: Ear (Hearing and Balance)

Question 1

The ear houses two senses:

Answer 1

Hearing and Equilibrium (balance)

Question 2

Are involved in both hearing and the
detection of equilibrium,

Answer 2

Mechanoreceptors

Question 3

The ear is divided into three areas

Answer 3

External (outer), middle, and internal (inner)

Question 4

Involved only in collecting sound waves

Answer 4

External ear

Question 5

→ The fleshy part on the outside of the head, primarily made of elastic cartilage covered with skin.
→ Its shape collects and directs sound towards the auditory canal.

Answer 5

Auricle (pinna)

Question 6

A short, narrow chamber (~1inch long and 1/4 inch wide) carved into the temporal bone, lined with skin and ceruminous glands.

Answer 6

External acoustic meatus (auditory canal)

Question 7

Protects the tympanic membrane

Answer 7

Cerumen (earwax)

Question 8

→ A thin, semi-transparent membrane separating the external ear from the middle ear.

Answer 8

Tympanic membrane (eardrum)

Question 9

Inner layer of the eardrum is made of

Answer 9

Simple cuboidal epithelium

Question 10

Middle layer of the eardrum is made of

Answer 10

Connective tissue

Question 11

Outer layer of the eardrum is made of

Answer 11

Stratified squamous epithelium

Question 12

→ Air-filled mucosa-lined cavit within the temporal bone Involved only in the sense of hearing.
→ Located between tympanic membrane and oval window and round window

Answer 12

Middle ear cavity

Question 13

→ Connects the middle ear to the throat, equalizing air pressure in the middle ear cavity so the eardrum can vibrate
→ Actions likes wallowing, yawning, or chewing can open the tube, relieving pressure on the tympanic membrane.
→ Equalizes pressure in the middle ear cavity so the eardrum can vibrate

Answer 13

Pharyngotympanic tube (Auditory tube)

Question 14

These bones transmit vibrations from the tympanic membrane to the inner ear

Answer 14

Auditory ossicles

Question 15

Vibrations travel from the…

Answer 15

Hammer to anvil to stirrup to oval window of inner ear

Question 16

Houses sense organs for both hearing and balance, located within the bony labyrinth of the temporal bone.

Answer 16

Internal (inner) ear

Question 17

Bony labyrinth (Osseous labyrinth) is divided into three regions:

Answer 17

Vestibule, cochlea, semicircular canals

Question 18

Bony labyrinth is filled with

Answer 18

Perilymph

Question 19

→ Resembles the bony labyrinth but is smiley and filled with endolymph (clear fluid).

Answer 19

Membranous labyrinth

Question 20

The space between the bony labyrinth and the membranous labyrinth is filled with ______

Answer 20

perilymph

Question 20

→ Similar to blood plasma; high sodium and low potassium concentration.
→ Supplies mechanical stimuli to the cochlea and vestibule

Answer 20

perilymph

Question 21

→ Low sodium and high potassium concentration
→ Created from perilymph; essential for hearing and balance.

Answer 21

Endolymph

Question 22

→ Located within the cochlear duct
→ Receptors = hair cells on the basilar membrane
→ Gel-like tectorial membrane is capable of bending hair cells
→ Cochlear nerve attached to hair cells transmits nerve impulses to auditory cortex in the temporal lobe

Answer 22

Spinal Organ of Corti

Question 23

Where can the hair cells be found

Answer 23

Basilar membrane

Question 24

→ Disturb the short, stiff fibers of the basilar membrane, stimulating receptor cells near the oval window.
→ Since high-pitched sounds have more energy, they can stimulate receptor cells close to the eardrum.

Answer 24

high pitched sounds

Question 25

Since high-pitched sounds have more energy, they can stimulate receptor cells close to the

Answer 25

eardrum

Question 26

The membranous labyrinth of the cochlea forms the cochlear duct, which is filled with

Answer 26

endolymph

Question 27

Where are the hearing receptors housed?

Answer 27

Spinal organ of corti

Question 28

Hearing receptors

Answer 28

hair cells

Question 29

Above the cochlear duct, filled with
perilymph.

Answer 29

Scalar vestibuli

Question 30

Below the cochlear duct, also filled with perilymph.

Answer 30

Scalar Tympani

Question 31

The vestibular membrane borders
the

Answer 31

scala vestibuli

Question 31

the basilar membrane borders the

Answer 31

scala tympani

Question 32

pressure waves cause vibrations in the basilar membrane within the

Answer 32

spiral organ of Corti.

Question 33

Once the hair cells are stimulated,
they send nerve impulses through the _____ to the auditory cortex in the temporal lobe of the brain.

Answer 33

cochlear nerve,

Question 34

Equilibrium is the body’s ability to maintain balance and orientation in response to head movements.

Answer 34

Equilibrium

Question 35

The receptors for equilibrium are located in the inner ear, collectively known as the

Answer 35

vestibular apparatus

Question 36

Static equilibrium is monitored by the

Answer 36

Maculae

Question 37

Dynamic equilibrium is monitored by the

Answer 37

Crista Ampullaris

Question 38

→ are the receptors for static equilibrium, located within the vestibule’s membranes.
→ They report the position of the head concerning gravity when the body is at rest, Help us keep our head erect

Answer 38

Maculae

Question 39

→ Information from the maculae is transmitted via the vestibular division of the ____________ to the cerebellum and the cerebral cortex of the brain.

Answer 39

vestibulocochlear nerve (Cranial Nerve VIII)

Question 40

Are embedded in a gelatinous structure known as the otolithic membrane.

Answer 40

Hair cells

Question 41

→ is studded with otoliths—tiny stones made of calcium carbonate that float in a gel around hair cells
→ Movements cause otoliths to roll and bend hair cells

Answer 41

Otolithic membrane

Question 42

→ It serves as the receptor for dynamic equilibrium
→ Located in the ampulla ofeach semicircular
→ There are three semicircular canals, oriented in different planes
○ Transverse plane, coronal plane, sagittal plane

Answer 42

Crista Ampullaris

Question 43

Each Crista Ampullaris consists of a ridge of epithelium with a curved gelatinous mass called the _____.

Answer 43

cupula

Question 44

→ When the head moves in a rotational or angular motion, the endolymph within the semicircular canals moves, displacing the cupula.
→ The movement of the cupula bends the hair cells, stimulating them to send impulses through the vestibular nerve to the cerebellum, which helps maintain balance during motion.

Answer 44

Mechanism of dynamic equilibrium

Question 45

→ When the head moves, the otoliths shift, causing the otolithic membrane to bend, which in turn bends the hair cells.
→ This bending stimulates the hair cells, sending impulses via the vestibular nerve to the brain.

Answer 45

Mechanism of static equilibrium

Question 46

→ results when the transmission of sound vibrations through the external and middle ears is hindered
→ Causes:
○ Buildup of earwax
○ Fusion of ossicles
○ Ruptured eardrum
○ Inflammation of the middle ear
→ This can be temporary or permanent.

Answer 46

Conduction deafness

Question 47

→ Occurs due to damage or degeneration of the receptor cells in the cochlea, the cochlear nerve, or neurons in the auditory cortex.
→ Often results from prolonged exposure to loud sounds.
→ Often results from prolonged exposure to loud sounds.

Answer 47

Sensorineural deafness

Question 48

→ A disorder affecting the inner ear,
leading to progressive deafness and
vertigo (a severe spinning sensation). → The condition can cause extreme
discomfort and instability.

Answer 48

Meniere’s syndrome