Ear

Question 1

Ear pinna is formed of…..while outer part of EAM is formed of…..

Answer 1

Yellow elastic fibro-cartialge
Yellow elastic cartilage

Question 2

Ceruminous glands are……, the function of their secretion is……

Answer 2

Modified apocrine sweat glands
Ear wax prevents objects from penetrating deep into the meatus

Question 3

The inner surface of tympanic membrane & the middle ear are lined by…..which transitions into…..in the Eustachian tube.

Answer 3

Simple cuboidal epithelial
Respiratory epithelium

Question 4

The function of tympanic membrane is…..
While function of bony ossicles is……., mention their lining

Answer 4

Transmits sound waves to the bony ossicles of the middle ear
Act as a lever, as they maginfy the vibration received from tympanic membrane to the oval window then to the inner ear. Lined by simple squamous epithelium.

Question 5

Action of tensor tympani is…..(1)while stapedius……(2)

Answer 5

1. Makes ear drum tense
2. Pukks stapes out to protect the organ of Corti from high vibrations

Question 6

Membranous labyrinth is filled with……while bony labyrinth is filled with…..

Answer 6

Endolymph
Perilymph

Question 7

The vestibule contains…….which are connected by……..and lined by……, their receptor areas are called……

Answer 7

Utricle & saccule
Utriculosaccular duct
Simple squamous epithelium
Maculae

Question 8

Compare type I & II hair cells

Answer 8

Type I: flask-shaped cells with rounded base & narrow apex, have rounded basal nuclei, they are completely surrounded. By afferent nerve terminal calyx.
Type II: They are more numerous, cylindrical, with button endings from afferent nerves
Both types contact many afferent & efferent nerve endings

Question 9

Hair cells have a single…..and many….. which are connected to……

Answer 9

Kinocilium
Stereoclia
Actin-rich apical cytoplasm (cuticular plate) which returns these rigid stereocilia to a normal upright position after bending.

Question 10

Tips of stereocilia are embedded in……., which is……

Answer 10

Otolithic membrane
It is a gelatinous proteoclycans layer with calcium carbonate crystals on its surface (otolith or otoconia)

Question 11

Dilated part of semicircular canals is…….and contains neuroepitheial area called……

Answer 11

Ampulla
Crista ampullaris

Question 12

Function of supporting cells & connections

Answer 12

1. Support & nutrition of hair cells
2. Production of otolithic membrane
   Junctional complex

Question 13

Mention differences between crista ampullaris & macula

Answer 13

Crista ampullaris is characterized by:
1. The proteoglycans kayer is called cupula, thicker & conically shaped with no otolith
2. The cupula extends across the ampulla establishing contact with the opposite wall

Question 14

The cochlea turns around……,…..times.

Answer 14

Modioulus
2 and 3/4

Question 15

In cochlea, a shelf extends laterally from modiolus called…..

Answer 15

Osseous spiral lamina

Question 16

The roof of cochlear duct is formed by ……separated from……. White its floor is formed by……separated from……. . Both these chambers communicate by…….

Answer 16

Vestibular membrane, scala vestibuli
Basilar membrane, sacala tympani
Helicotrema

Question 17

Structure & function of vestibular membrane

Answer 17

It is formed of 2 layers of simple squamous epithelium separated by their basement membranes, with extensive tight junctions, that help maintain the high ionic gradients between the 2 compartments.

Question 18

Structure & function of basilar membrane

Answer 18

Formed of amorphous material containing keratin-like fibers. Extending from osseous spiral lamina to spiral ligament on lateral wall. It supports organ of Corti.

Question 19

Structure & function of stria vascularis

Answer 19

Area of stratified epithelium covering the spiral ligament on lateral wall of cochlear duct. Contains intraepithelial capillary plexus. They are ion transporting cells responsible for secretion & maintenance of endolymph of entire membranous labyrinth.

Question 20

Compare inner hair cells & outer hair cells

Answer 20

Inner: single row of cells supported by outer phalyngeal cells, short, flask-shaped with central nuclei, apical surface contain stereocilia arranged in linear array. More richly innervated.
Outer: 3-5 rows of cells supported by inner phalyngeal cells, long, columnar cells with basal nuclei, apical surface contains stereocilia arranged as V-shaped bundles, less innervated.

Question 21

Structure & function of tectorial membrane

Answer 21

It is an acellular membrane that extends over Organ of Corti from vonnective tissue of modiolus. It consists of fine bundles of CT (types II, V, IX, XI) associated with proteoglycans. It is secreted bt the cells covering the spiral limbus.
Stereocilia of the hair cells are embedded in this membrane.

Question 22

Pillar cells rest on……, separated by…..

Answer 22

Basilar membrane
Inner tunnel of Corti

Question 23

Compare outer and inner phalangeal cells

Answer 23

O, they support the base of outer hair cells by their cup shaped apices
I, they surround and support the inner hair cells completely, apical ends joined by tight junctions.

Question 24

Describe extension on medial longitudinal fasciculus

Answer 24

It extends upwards till interstitial nucleus of Cajal in posterior commissure and below continues in spinal cord as medial vestibulospinal tract
It connects vestibular and cochlear nuclei with motor nuclei of cranial nerves that move the eye (III, IV, VI) and with the spinal nucleus of accessory nerve that moves the neck.

Question 25

Mention functions of MLB

Answer 25

Involved in:
1. Coordination of movements of eye and head in reponse to vesticulo-cochlear stimuli
2. Pathway for conjugate eye movements as it connects abducent nucleus of one side to oculomotor nucleus of the other side.

Question 26

Deacribe vestibular pathway frpm receptors to nuclei

Answer 26

Receptors are present in semicircular canals (crista ampullaris) and saccule/utricle (maculae)
These receptors send impulses to vestibular ganglion. Its central process forms vestibular nerve passes in IAM, enter posterior cranial fossa and pass through cerebellopontine angle and reach brain stem to end on vestibular nuclei which are located on the floor of 4th ventricle in pons and medulla. They are superior, inferior, medial and lateral.

Question 27

Mention the connections of vestibular nuclei

Answer 27

1. Cerebellum through ICP to flocculonofular lobe
2. Spinal cord form vestibulo-spinal tract
3. MLB to connect with nuclei of III,IV,VI
4. Thalamus to connect to vestibular cortical area

Question 28

Describe site and function of vestibular cortical area

Answer 28

S, superior temporal gyrus glose to 1ry auditory area
F, receives information about the head position and movements from vestibular nuclei after relay in VPMN of thalamus.

Question 29

Lesion of vestibular n leads to……

Answer 29

Dizziness and vertigo