Fluid Of Inner Ear
Endolymph in the inner ear:
| A |
Is a filterate of blood serum |
|
| B |
Is secreted by Stria vascularis |
|
| C |
Is secreted by Basilar membrane |
|
| D |
Is secreted by Hair cells |
Endolymph in the inner ear:
| A |
Is a filterate of blood serum |
|
| B |
Is secreted by Stria vascularis |
|
| C |
Is secreted by Basilar membrane |
|
| D |
Is secreted by Hair cells |
Is secreted by Stria vascularis [Ref: Ds. of ENT by P.L. Dhingra 5/e p12] Repeat from May 09
There are 2 main fluids in the inner ear:
- Endolymph
– It fills the entire membranous labyrinth
– Resembles intracellular. fluid, being rich in K ions.
– It is secreted by the secretory cells of the stria vascularis of the choclea and by the dark cells (present in the utricle and near the ampullated ends of semicircular ducts).
- Perilymph
– It fills the space between the bony and the membranous labyrinth.
– It resembles extra cellular fluid being rich in Na ions.
– It communicates with CSF through the aqueduct of cochlea which opens into the scala tympani near the round window.
– There are 2 views regarding its formation:
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.
| A | Helicotrema | |
| B |
Scala media |
|
| C |
Scala tympani |
|
| D |
Scala vestibuli |
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+).
| A |
has low concentration of K+ and high concentration of Na+ |
|
| B |
Is secreted by Stria vascularis |
|
| C |
Is secreted by Basilar membrane |
|
| D |
None is true |
Endolymphatic duct drains into :
| A |
Subdural space |
|
| B |
External space |
|
| C |
Subarachnoid space |
|
| D |
Saccule |
Ans:A.)Subdural space
Perilymph drains into subarachnoid space through the aqueduct of cochlea.
Endolymph is absorbed in subdural space.
Site where endolymph is seen:
| A |
Scala vestibuli |
|
| B |
Scala media |
|
| C |
Helicotrema |
|
| D |
Organ of corti |
The function of stria vascularis is:
| A |
To produce perilymph |
|
| B |
To absorb perilymph |
|
| C |
To maintain electric milieu of endolymph |
|
| D |
To maintain electric milieu of perilymph |
Ans. C. To maintain electric milieu of endolymph
- Scala vestibuli and scala tympani are filled with perilymph, whereas scala media/membranous cochlea is filled with endolymph.
| A |
Is a filterate of blood serum |
|
| B |
Is secreted by stria vascularis |
|
| C |
Is secreted by basilar membrane |
|
| D |
Is secreted by hair cells |
Endolymph is rich in ‑
| A |
Na+ |
|
| B |
Cl– |
|
| C |
HCO–3 |
|
| D |
K+ |
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 filtrate 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).
