Internal ear

INTERNAL EAR

Q. 1

Otoacoustic emissions arise from ______

 A

Outer hair cells

 B

Inner hair cells

 C

Both

 D

Organ of corti

Q. 1

Otoacoustic emissions arise from ______

 A

Outer hair cells

 B

Inner hair cells

 C

Both

 D

Organ of corti

Ans. A

Explanation:

 

Otoacoustic Emissions (OAEs)

They are low intensity sounds produced by outer hair cells of a normal cochlea and can be elicited by a very sensitive microphone placed in the external ear canal and an analysis by a computer. Sound produced by outer hair cells travels in a reverse direction:

Outer hair cells→basilar membrane→ perilymph→ oval window→ ossicles→ tympanic membrane→ ear canal.


Q. 2

Shortest part of VIIth cranial nerve is in:

 A

Pons

 B

Superior colliculus

 C

Stylomastoid region

 D

Labyrinthine canal 

Q. 2

Shortest part of VIIth cranial nerve is in:

 A

Pons

 B

Superior colliculus

 C

Stylomastoid region

 D

Labyrinthine canal 

Ans. D

Explanation:

Q. 3

Which of the following structures contains endolymph?

 A

Helicotrema

 B

Scala media

 C

Scala tympani

 D

Scala vestibuli

Q. 3

Which of the following structures contains endolymph?

 A

Helicotrema

 B

Scala media

 C

Scala tympani

 D

Scala vestibuli

Ans. B

Explanation:

The cochlea of the inner ear is a coiled structure filled with endolymph and perilymph. Within it are three longitudinal compartments. The membranous labyrinth within the cochlea is called the scala media, or cochlear duct. This compartment contains the hair receptors and is filled with endolymph that is secreted by the stria vascularis. The composition of endolymph resembles intracellular fluid (K+> Na+).

The two perilymph-filled compartments, the scala tympani and the scala vestibuli surround the cochlear duct. This space is continuous with subarachnoid space, and therefore the perilymph closely resembles cerebrospinal fluid. The helicotrema is the apical connection between the scala tympani and scala vestibuli.
 
The spiral ganglion is located in the modiolus (the cochlear part of the body labyrinth), and contains the cell bodies of the bipolar cells that comprise the cochlear division of the eighth nerve.

Q. 4

In which of the following part, VIIth nerve take a narrowest path during its entire course?

 A

Pons

 B

Sup. colliculus

 C

Stylomastoid region

 D

Labyrinthine canal

Q. 4

In which of the following part, VIIth nerve take a narrowest path during its entire course?

 A

Pons

 B

Sup. colliculus

 C

Stylomastoid region

 D

Labyrinthine canal

Ans. D

Explanation:

At the lateral portion of the IAC, the facial nerve pierces the meatal foramen to enter the labyrinthine segment.

The labyrinthine segment is notable in that it is the narrowest portion 

As a result, it is believed that infections or inflammations of the facial nerve within this region can lead to temporary or permanent paralysis of the nerve, such as in Bell’s palsy.
 

Q. 5

Which of the following chambers of the cochlea is filled with a fluid similar to intracellular fluid with high K+ and low Na+?

 A

Scala vestibuli

 B

Scala media

 C

Scala tympani

 D

All of the above

Q. 5

Which of the following chambers of the cochlea is filled with a fluid similar to intracellular fluid with high K+ and low Na+?

 A

Scala vestibuli

 B

Scala media

 C

Scala tympani

 D

All of the above

Ans. B

Explanation:

The cochlea is divided into three chambers by a basilar and reissner’s membrane.

The upper chamber is known as scala vestibuli, the lower chamber is scala tympani and the middle chamber is known as scala media.

Endolymph is a potassium rich fluid and is present in scala media. Its composition is similar to intracellular fluid. The endolymph here is secreted by the stria vascularis which forms the lateral wall of scala media.
 
Perilymph is a fluid present in scala vestibuli and scala tympani. Its composition is similar to extracellular fluid in that it is high in Na+ and low in K+.
 

Q. 6

Labyrinthine artery is a branch of?

 A

Posterior inferior cerebellar artery

 B

Vertebral artery

 C

Posterior cerebral artery

 D

Anterior inferior cerebellar artery

Q. 6

Labyrinthine artery is a branch of?

 A

Posterior inferior cerebellar artery

 B

Vertebral artery

 C

Posterior cerebral artery

 D

Anterior inferior cerebellar artery

Ans. D

Explanation:

The labyrinthine artery (auditory artery, internal auditory artery), a long slender branch of the anterior inferior cerebellar artery (85%-100% cases) or basilar artery.


Q. 7

True about internal ear anatomy

 A

Three semicircular canals here 6 openings into the vestibule

 B

The angle between anterior & posterior SCC is 180°

 C

Vestible is the central chamber

 D

Spiral canal makes 2 turns

Q. 7

True about internal ear anatomy

 A

Three semicircular canals here 6 openings into the vestibule

 B

The angle between anterior & posterior SCC is 180°

 C

Vestible is the central chamber

 D

Spiral canal makes 2 turns

Ans. C

Explanation:

C i.e. Vestible is the central chamber


Q. 8

Promontory seen in the middle ear is:

 A

Jugular bulge

 B

Basal turn of cochlea

 C

Semicircular canal

 D

Head of incus

Q. 8

Promontory seen in the middle ear is:

 A

Jugular bulge

 B

Basal turn of cochlea

 C

Semicircular canal

 D

Head of incus

Ans. B

Explanation:

Q. 9

Inner ear bony labyrinth is:

 A

Strongest bone in the body

 B

Cancellous bone

 C

Cartilaginous bone

 D

Membranous bone

Q. 9

Inner ear bony labyrinth is:

 A

Strongest bone in the body

 B

Cancellous bone

 C

Cartilaginous bone

 D

Membranous bone

Ans. C

Explanation:

 

Bony labyrinth is an example of cartilaginous bone (i.e. a bone which ossification cartilage).


Q. 10

Cochlear aqueduct:

 A

Connects internal ear with subarachnoid space

 B

Connects cochlea with vestibule

 C

Contains endoylymph

 D

Same as S media

Q. 10

Cochlear aqueduct:

 A

Connects internal ear with subarachnoid space

 B

Connects cochlea with vestibule

 C

Contains endoylymph

 D

Same as S media

Ans. A

Explanation:

Q. 11

Organ of corti is situated in:

 A

Scala media

 B

Sinus tympani

 C

Sinus vestibuli

 D

Saccule

Q. 11

Organ of corti is situated in:

 A

Scala media

 B

Sinus tympani

 C

Sinus vestibuli

 D

Saccule

Ans. A

Explanation:

Q. 12

Endolymphatic duct connects which structure?

 A

Scala media to subdural space

 B

Scala vestibule to aqueduct of cochlea

 C

Scala tympani to aqueduct of cochlea

 D

Scala tympani to subdural space

Q. 12

Endolymphatic duct connects which structure?

 A

Scala media to subdural space

 B

Scala vestibule to aqueduct of cochlea

 C

Scala tympani to aqueduct of cochlea

 D

Scala tympani to subdural space

Ans. A

Explanation:

 

Endolymphatic duct – It is a part of membranous labyrinth (Scala media)

  • It is formed by union of saccule and utricle
  • It connects scala media to subdural space
  • Its terminal part is dilated to form the endolymphatic sac
  • Endolymphatic sac lies between the two layers of dura on the posterior surface of petrous bone
  • Surgical importance – Endolymphatic sac is exposed for drainage or shunt operation in Meniere’s disease

 


Q. 13

Site where endolymph is seen:

 A

Scala vestibuli

 B

Scala media

 C

Helicotrema

 D

Organ of corti

Q. 13

Site where endolymph is seen:

 A

Scala vestibuli

 B

Scala media

 C

Helicotrema

 D

Organ of corti

Ans. B

Explanation:

Q. 14

What are the boundaries of Trauttmann’s triangle?

 A

Bony labyrinth anteriorly

 B

Bony labyringh posteriorly

 C

Sigmoid sinus posteriorly

 D

a and c

Q. 14

What are the boundaries of Trauttmann’s triangle?

 A

Bony labyrinth anteriorly

 B

Bony labyringh posteriorly

 C

Sigmoid sinus posteriorly

 D

a and c

Ans. D

Explanation:

 

Trautmann’s triangle is bounded by the bony labyrinth anteriorly, sigmoid sinus posteriorly and the dura or superior petrosal sinus superiorly


Q. 15

Not included in bony labyrinth:

 A

Cochlea

 B

Semicircular canal

 C

Organ of Corti

 D

Vestibule

Q. 15

Not included in bony labyrinth:

 A

Cochlea

 B

Semicircular canal

 C

Organ of Corti

 D

Vestibule

Ans. C

Explanation:

Q. 16

The bony cochlea is a coiled tube making turns around a bony pyramid called:

 A

2, 1/4 modiolus

 B

2, 1/2 helicotrema

 C

2, 3/4 modiolus

 D

2, 3/4 helicotrema

Q. 16

The bony cochlea is a coiled tube making turns around a bony pyramid called:

 A

2, 1/4 modiolus

 B

2, 1/2 helicotrema

 C

2, 3/4 modiolus

 D

2, 3/4 helicotrema

Ans. C

Explanation:

Q. 17

Sense organ for hearing is

 A

Organ of Corti

 B

Cristae

 C

Macula

 D

None

Q. 17

Sense organ for hearing is

 A

Organ of Corti

 B

Cristae

 C

Macula

 D

None

Ans. A

Explanation:

Q. 18

Hair cell of organ of Corti is supported by:

 A

Onodi cells

 B

Deiter cell

 C

Hensen cell

 D

b and c

Q. 18

Hair cell of organ of Corti is supported by:

 A

Onodi cells

 B

Deiter cell

 C

Hensen cell

 D

b and c

Ans. D

Explanation:

 

Supporting cells in organ of corti are PHD i.e. Pillar cells, Hensen cells and Dieter cells.

Hellar cells are ethmoidal air cell that extend along the medial roof of the maxillary sinus.

They may exist as a discrete cells or the may open into maxillary sinus or infundibulum                                

                                                      



Q. 19

Endolymph is rich in ‑

 A

Na+

 B

Cl

 C

HCO3

 D

K+

Q. 19

Endolymph is rich in ‑

 A

Na+

 B

Cl

 C

HCO3

 D

K+

Ans. D

Explanation:

Ans. is ‘d’ i.e., K+

Fluid in inner ear

  • There are two main fluids in the inner ear : –

(i) Perilymph                  

(ii) Endolymph

Perilymph

  • It resembles ECF and is rich in Nu+ ions. It fills the space between bony and the membranous labyrinth, i.e., Scala vestibuli and scala tympani. It communicates with CSF through the aqueduct of Cochlea which opens into the scala tympani near the round window. Therefore It closely resembles CSF. It is formed by : –

i) It is a filterate of blood serum and is formed by capillaries of the spiral ligament.

ii) It is a direct continuation of CSF and reaches the labyrinth via aqueduct of cochlea.

Endolymph

It fills the entire membranous labyrinth including scala media (cochlear duct). It resembles intracellular fluid, being rich in IC ions. It is secreted by the secretory cells of the stria vascularis of the cochlea and by the dark cells (present in the utricle and near the ampullated ends of semicircular ducts).


Q. 20

Horizontal acceleration with forward movement in the sagittal plane is detected by ‑

 A

Macula of Utricle

 B

Macula of Saccule

 C

Lateral semicircular canal

 D

Posterior semicircular canal

Q. 20

Horizontal acceleration with forward movement in the sagittal plane is detected by ‑

 A

Macula of Utricle

 B

Macula of Saccule

 C

Lateral semicircular canal

 D

Posterior semicircular canal

Ans. A

Explanation:

Ans. is ‘a’ i.e., Macula of utricle


Q. 21

Movement of the structure marked as “A” in the picture below causes vibration in ? 

 A

Scala media.

 B

Scala tympani.

 C

Scala vestibuli.

 D

Semicircular canal.

Q. 21

Movement of the structure marked as “A” in the picture below causes vibration in ? 

 A

Scala media.

 B

Scala tympani.

 C

Scala vestibuli.

 D

Semicircular canal.

Ans. C

Explanation:

The structure marked as A in the picture above represents the stapes.

Movement of stapes causes vibration in Scala vestibuli.



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