Question 1

The inner ear arises from which structure?&#10;A) First pharyngeal pouch&#10;B) First pharyngeal cleft&#10;C) Otic placode&#10;D) Hindbrain

Accepted Answer

The otic placode is a thickening of ectoderm that gives rise to the inner ear during early embryonic development.

Question 2

Microtia/anotia can be associated with other birth defects as a component of a syndrome.What percentage of children with microtia/anotia would be expected to have additional congenital abnormalities?&#10;A) 5%-10%&#10;B) 10%-20%&#10;C) 20%-40%&#10;D) 50%-80%&#10;E) Essentially 100%

Accepted Answer

Microtia/anotia, conditions affecting the external ear, can be associated with other congenital abnormalities in about 20%-40% of cases. This reflects the complex developmental origins of these conditions and their potential linkage with broader developmental syndromes.

Question 3

The prosensory region in the saccule forms which structure(s)?&#10;A) Cristae&#10;B) Organ of Corti&#10;C) Maculae

Accepted Answer

The prosensory region in the saccule forms the maculae, which are sensory organs responsible for detecting linear acceleration and head position in the vertical plane. The cristae are sensory organs located in the semicircular canals and are responsible for detecting rotational acceleration, while the Organ of Corti is part of the cochlea and is responsible for auditory sensation.

Question 4

The number of hair and supporting cells in the inner ear is determined by which signaling pathway?&#10;A) Planar polarity pathway&#10;B) Wnt canonical pathway&#10;C) Notch lateral inhibition pathway&#10;D) Fgf signaling&#10;E) Shh signaling

Accepted Answer

The Notch lateral inhibition pathway is responsible for determining the number of hair and supporting cells in the inner ear. This pathway ensures that adjacent cells adopt different fates by inhibiting the differentiation of neighboring cells along the same pathway.

Question 5

Branchio-oto-renal syndrome,characterized by kidney and hearing defects,is due to mutation of which gene?&#10;A) EYES ABSENT HOMOLOG 1(EYA1)&#10;B) EYES ABSENT HOMOLOG 4 (EYA4)&#10;C) POU4F3&#10;D) CONNEXIN 26&#10;E) FGF8

Accepted Answer

Branchio-oto-renal syndrome is caused by mutations in the EYA1 gene, which provides instructions for making a protein that is involved in the development of several organs including the kidneys, ears, and branchial arches. Mutations in this gene can cause structural abnormalities in the kidney and ear, leading to hearing loss and kidney dysfunction.

Question 6

Which signaling pathway controls the orientation and arrangement of the stereocilia on the inner hair cells?&#10;A) Wnt canonical&#10;B) Planar polarity&#10;C) Fgf&#10;D) Bmp&#10;E) Hedgehog

Accepted Answer

The planar polarity signaling pathway controls the orientation and arrangement of the stereocilia on the inner hair cells in the inner ear. This pathway involves the proteins Vangl2, Frizzled6, and Disheveled, which regulate the asymmetrical distribution of cell surface molecules and the actin cytoskeleton to establish and maintain cochlear hair cell polarity.

Question 7

Hereditary deafness can result from mutations in many genes.Which gene is mutated most frequently in nonsyndromic congenital deafness?&#10;A) CONNEXIN 26&#10;B) MYO7A&#10;C) CADHERIN 23&#10;D) HARMONIN&#10;E) PROTOCADHERIN 15

Accepted Answer

The most frequent gene mutated in nonsyndromic congenital deafness is Connexin 26 (CX26). This gene accounts for up to 50% of genetic deafness cases in some populations. Mutations in other genes such as MYO7A, Cadherin 23, Harmonin, and Protocadherin 15 can also lead to hereditary deafness but are less common.

Question 8

The cristae detect which modality?&#10;A) Sound vibrations&#10;B) Gravity&#10;C) Linear acceleration&#10;D) Angular acceleration

Accepted Answer

The cristae are sensory structures located in the semicircular canals of the inner ear and are responsible for detecting angular acceleration, which is the rotation of the head.

Question 9

Which muscle(s)are associated with the ear ossicles?&#10;A) Tensor tympani and stapedius&#10;B) Stylopharyngeus&#10;C) Stylohyoid&#10;D) Lateral pterygoid

Accepted Answer

The muscles associated with the ear ossicles are the tensor tympani and stapedius. The tensor tympani muscle attaches to the malleus (one of the ossicles) and helps to dampen loud noises. The stapedius muscle attaches to the stapes (another ossicle) and also helps to reduce the transmission of sound waves to the inner ear.

Question 10

Development of the sensory regions of the inner ear involves the formation of hair cells and supporting cells by the process of lateral inhibition controlled by Notch signaling.How would overexpression of the transcription factors Hes1 and 5,which are modulated by Notch signaling,be expected to affect the number of hair cells or supporting cells?

A) The overall number of supporting cells would increase.
B) The overall number of supporting cells would decrease.
C) The overall number of hair cells would increase.
D) The overall number of hair cells would decrease.
E) No change would occur in the number of hair cells or supporting cells.

Accepted Answer

Overexpression of Hes1 and 5, which are modulated by Notch signaling, would be expected to increase the overall number of supporting cells because Notch signaling is involved in lateral inhibition, which controls the formation of hair cells and supporting cells. Overexpression of Hes1 and 5 would disrupt this process, leading to an increase in the number of supporting cells.

Question 11

Would mutation in genes that encode cytoskeletal components such as ACTIN,ESPSIN,and HARMONIN be expected to result in sensorineural or conductive hearing loss?&#10;A) Sensorineural&#10;B) Conductive

Accepted Answer

The answer of Would mutation in genes that encode cytoskeletal...

Question 12

Researchers have genetically inactivated transcription factors that are expressed in the developing ear of mice.This has shown that various transcription factors are necessary for the development of different regions of the inner ear.Pax2 function is required for development of which region of the inner ear?

A) Lateral canal
B) Anterior and posterior canals
C) Cochlea
D) Utricle
E) Endolymphatic duct and sac

Accepted Answer

The answer of Researchers have genetically inactivated transcription factors that...

Deck 19: Development of the Ears