CANS

Question 1

What is the purpose of the Cerebellum?

Answer 1

Balance; produces changes in skeletal muscle tone and maintain posture and coordinate movement

Question 2

Is the CANS a direct transmission line to the cortex? Why or why not?

Answer 2

No; its a complex signal processing as the nerve fiber reaches its nucleus, then the nerve fiber ends and a synapse takes place with the next nerve.

Question 3

What is the cerebellopontine angle (CPA) and where is it’s location?

Answer 3

Where cerebellum, pons and medulla oblongata meet

beyond the IAC attached to the brainstem

Question 4

Define decussation

Answer 4

Crossover point that unites symmetrical portions of the brains two halves

Question 5

What happens in the trapezoid body (first decussation) and where is it’s location?

Answer 5

• Located in the pons

- It is what nerve fibers from the cochlear nucleus travel through

Question 6

What happens in the superior olivary complex (first place to get info from both sides of brain)?

Answer 6

A group of nuclei in the pons; most nerve fibers from the trapezoid body will attach contralaterally to the SOC

Question 7

What happens in the lateral lemniscus (largest fiber tract)?

Answer 7

• Where SOC sends projections; its fiber tract is from the pons to the midbrain
• Place where directional information is combined with other sound coding to create complex sound image

Question 8

Where is the inferior colliculus (2nd site for binaural coding) located?

Answer 8

Midbrain

Question 9

What happens in the medial geniculate body (no decussations….limbic system) and where is it located?

Answer 9

Answer:

It is the final processing stage and it is located at the thalamus

Question 10

What happens in Heschl’s gyrus (primary cortex) and where is it located?

Answer 10

• Receives and synthesizes auditory information coming from the MGB
• Located in temporal lobe of the cerebral cortex

Question 11

What do you know about binaural processing in the SOC (localization, distance estimation and understanding speech in noise)-IID, ITD?

Answer 11

• Localization will depend on the time of sound arrival at the two ears and the intensity difference at the two ears. (ITD’s for low frequencies, IID’s for high frequency)
• Inhibition of OHC motility will improve detection, localization and perception of speech in background noise

Question 12

Where does the efferent system begin and what is the significance of the SOC-olivocochlear bundle)?

Answer 12

• Begins in the auditory cortex
• The olivocochlear bundle controls electromotility of OHC’s, reducing OHC activity. This in turn decreases the amplification of the auditory signal at the level of the cochlea