LEC 18 - Olfaction vision and hearing part 2

Question 1

Describe the primary functions of the ear as a whole.

Answer 1

The ear functions to protect, absorb, and transform air pressure waves into mechanical vibratory energy (external and middle ear) and to absorb and transform mechanical energy into neural impulses (inner ear).

Question 2

Identify the structures that comprise the external ear and their functions.

Answer 2

The external ear includes:
Auricle (Pinna): Protects the canal, captures sound, and provides directional sensitivity.

External Auditory Canal (Meatus): Channels sound waves to the tympanic membrane (eardrum).

Question 3

How does the auricle enhance sound directionality?

Answer 3

The auricle captures sound waves and enhances directional sensitivity, allowing for better localization of sound sources.

Question 4

Define the external acoustic canal’s structure.

Answer 4

its lateral portion being cartilaginous and the medial portion being osseous, directed slightly downward to prevent foreign particle accumulation.

Question 5

What is the function of ceruminous glands?

Answer 5

Ceruminous glands secrete cerumen (earwax), which helps keep foreign objects and insects out of the tympanic membrane and slows the growth of microorganisms.

Question 6

How can excessive cerumen buildup affect hearing?

Answer 6

Excessive wax can block sound transmission to the tympanic membrane, leading to temporary hearing loss.

Question 7

Describe the role of the tympanic membrane in hearing.

Answer 7

The tympanic membrane separates the external and middle ear and conducts vibrations from the external ear to the middle ear.

Question 8

Describe the layers that compose the tympanic membrane.

Answer 8

The tympanic membrane consists of a thin layer of connective tissue sandwiched between two layers of epithelium.

Question 9

How does the middle ear function in sound transmission?

Answer 9

The middle ear conducts vibrations from the tympanic membrane to the oval window and amplifies these vibrations.

Question 10

Explain the structure of the middle ear (tympanic cavity).

Answer 10

The middle ear is an irregular space within the temporal bone, and contains the ossicles.

Question 11

Define the ossicles and their function and where it is

Answer 11

The ossicles are three bones: the malleus, incus, and stapes, which conduct and amplify vibrations from the tympanic membrane to the oval window. In middle ear (tympanic cavity)

Question 12

How does the external ear contribute to sound processing?

Answer 12

The auricle captures sound waves, while the S-shaped external acoustic canal directs these waves toward the tympanic membrane for mechanical transformation.

Question 13

Describe mechanical transduction in the inner ear.

Answer 13

Mechanical transduction in the inner ear involves absorbing mechanical energy from vibrations and transforming it into neural impulses sent to the brain for auditory processing.

Question 14

What is the role of the middle ear in amplifying sound?

Answer 14

The middle ear amplifies sound vibrations received from the tympanic membrane before transmitting them to the oval window.

Question 15

Describe the medial wall of the middle ear.

Answer 15

The medial wall features the oval window, occupied by the foot plate of the stapes, which transmits vibrations into the inner ear, and the round window, which helps diffuse returning vibrations from the cochlea.

Question 16

Define the auditory tube and its alternate names.

Answer 16

The auditory tube, also known as the Eustachian tube or pharyngotympanic tube, is a passageway between the middle ear and the nasopharynx.

Question 17

Explain the primary functions of the auditory tube.

Answer 17

The auditory tube equalizes pressure in the middle ear, provides a passage for microorganisms (which can lead to otitis media), and allows drainage of fluid from the middle ear.

Question 18

How does pressure difference affect the auditory tube?

Answer 18

An air pressure difference between the ear canal and middle ear can build up, and the Eustachian tube can open via palatine muscle activation to equalize pressures, often experienced as ‘popping’ the ears through swallowing, yawning, or chewing.

Question 19

Identify the muscles responsible for opening the Eustachian tube.

Answer 19

The main muscles responsible for opening the Eustachian tube are the levator veli palatini and tensor veli palatini.

Question 20

Explain the method to equalize pressure while scuba diving.

Answer 20

While scuba diving, pressure is equalized by ‘pushing’ air (positive pressure) into the middle ear while pinching the nose closed with fingers, which can cause the eardrums to pop the opposite direction.

Question 21

How does pressure buildup differ when ascending into the air versus descending underwater?

Answer 21

When ascending into the air, there is a pressure buildup in the middle, whereas when descending underwater, the pressure difference builds in the opposite direction.

Question 22

Define the ossicular chain and the bones it includes.

Answer 22

The ossicular chain connects the tympanic membrane to the oval window and includes the malleus (hammer), incus (anvil), andapes (stirrup).

Question 23

Describe how the ossicular chain amplifies sound vibrations.

Answer 23

The ossicular chain amplifies sound by transferring force from the eardrum to the oval window.

Question 24

What does the Eustachian tube play in ear health?

Answer 24

The Eustachian tube helps equal air pressure in the middle ear and facilitates drainage, which is essential for preventing infections and maintaining ear health.

Question 25

How can the Eustachian tube contribute to ear infections?

Answer 25

The Eustachian tube can provide a passage for microorganisms, which can lead to infections such as otitis media.

Question 26

Explain the significance of the oval and round windows in the middle ear.

Answer 26

The oval window transmits vibrations from the stapes to the inner ear, while the round window helps to dissipate pressure waves returning from the cochlea.

Question 27

Describe the connection of the incus to other structures in the ear.

Answer 27

The incus has a body and two processes: a short process in the epitympanic recess and a long process connecting to the stapes via a ball-and-socket joint.

Question 28

Explain the role of the stapes in sound transmission.

Answer 28

The stapes has a head, neck, two crura, and a footplate. It connects to the incus at the head and transmits vibrations to the cochlea through the footplate in the oval window.

Question 29

Describe the acoustic reflex and its purpose.

Answer 29

The acoustic reflex involves the tensor tympani and stapedius muscles, reduces sound by limiting movement of the tympanic membrane and stapes.

Question 30

Define the function of the tensor tympani muscle.

Answer 30

The tensor tympani stiffens the tympanic membrane and is innervated by the trigeminal nerve (CN5).

Question 31

How does the stapedius muscle contribute to sound protection?

Answer 31

The stapedius muscle limits stapes movement at the oval window to protect the ear from loud sounds. It is innervated by the facial nerve (CN7).

Question 32

Identify the three regions of the inner ear and their functions.

Answer 32

The inner ear consists of the vestibule (senses gravity and acceleration), semicircular canals (sense head rotation), and cochlea (detects sound).

Question 33

Differentiate between the bony labyrinth and the membranous labyrinth.

Answer 33

The bony labyrinth is within the temporal bone and contains perilymph, while the membranous labyrinth is filled with endolymph. The two fluids do not mix.

Question 34

What is the role of the vestibule in the inner ear?

Answer 34

The vestibule contains the saccule and utricle, which provide equilibrium sensation

Question 35

How does the vestibule communicate with the semicircular canals?

Answer 35

The vestibule opens into the three semicircular canals, allowing for the integration of balance and spatial orientation.

Question 36

Describe the role of the ampullae in the semicircular canals.

Answer 36

Each semicircular canal contains an ampulla, houses sensory receptors (hair cells)

Question 37

How do hair cells in the vestibular apparatus contribute to equilibrium?

Answer 37

Hair cells in the vestibular apparatus detect head movements: semicircular canals sense angular acceleration, while the vestibule detects linear acceleration and static equilibrium.

Question 38

How does movement of endolymph within the semicircular canals affect hair cells?

Answer 38

Endolymph movement bends the cupula, stimulating hair cell stereocilia and activating signals in the Vestibulocochlear nerve (CN VIII) for balance and posture.

Question 39

Which semicircular ducts correspond to specific head movements?

Answer 39

The lateral duct detects side-to-side rotation, the anterior duct detects nodding, and the posterior duct detects head tilting side to side.