CLASS DISCUSSION
Module 12
The auditory and vestibular systems are pretty easy topics and the plan is for tutors to spend a limited time discussing them with their groups. There is a single clinical problem and it is rather straightforward. So, the idea is to set aside 20 minutes or so of this lab to give students a chance to clear up questions about the (branchomeric) cranial nerves. With that in mind, topics 4 and 5 below provide access some of that material. Another strategy is simply to go back to the discussion page for Module 8 to call up figures if needed.
Special note regarding the vestibular lecture on Wednesday. The discussion of Figure 9 was a bit rushed and not as clear as it should have been. The macula of the utricle lies in the horizontal plane. Cells there respond to any tilt away from the horizontal; they also respond to linear (as opposed to angular) acceleration in a direction parallel to the horizontal plane. The macula of the saccule lies in a vertical plane; it is more difficult to figure out how it responds to tilt, but it is said to respond to linear acceleration in an upward or downward direction.
TOPIC 1 - The auditory pathway. Probably it is best to start with an over-all diagram of the pathway.
1) -
2) - FIGURE 12-2 This is the module view. It makes use of our standard dorsal view of the brainstem and it relates the pathway to actual slide levels, but it may be too cluttered to use for the first look at the system
TOPIC 2 - Key Slides - Auditory Pathway. The best way to look at the auditory pathway is to look at slide 7, and then just click on "rostral" to go through the series. But, I'll list 11 "key" slides below
3) - Cu Slide 7 - the dorsal and posteroventral cochlear nuclei; formation of dorsal and intermediate acoustic stria
4) - Cu Slide 8 - the anteroventral cochlear nucleus
5) - Cu Slide 9 - formation of ventral acoustic stria
6) - Cu Slide 12 - the trapezoid body and superior olive
7) - Cu Slide 14 - the lateral lamniscus
8) - Cu Slide 16 - the lateral lemniscus approaches the inferior colliculus
9) - Cu Slide 18 - the lateral lemniscus enters the inferior colliculus
10) - Cu Slide 20 - the brachium ascends toward the medial geniculate nucleus
11) - Cu Slide 22 - the medial geniculate nucleus
12) - Cu Slide 28 - the auditory radiation
13) - HF Slide 30 - the auditory radiation
TOPIC 3 - Key Slides - Vestibular Pathway. Here are the highlites. The vestibular nerve enters the brainstem slightly rostral to the cochlear nerve. The fibers can barely be seen as they pass dorsomedially, squeezing their way between the spinal tract of the trigeminal and the inferior cerebellar peduncle, to reach the vestibular nuclei (#14). #15 shows where the nuclei are on a dorsal view of the brainstem and gives you a way to call them up. You should be able to identify the inferior and medial vestibular nuclei on slides like Cu slide 6 (#16) or Cu slide 7 (#17)
14) - Cu Slide 10 - the vestibular nerve enters the brainstem
15) - FIGURE 12-5 - the four vestibular nuclei on a dorsal view of the brainstem
16) - Cu Slide 6 - the medial and inferior vestibulat nuclei - the only two you can identify on our slides
17) - Cu Slide 7 - the medial and inferior vestibulat nuclei - the only two you can identify on our slides
IThe next views show the formation of the vestibulospinal tracts.
18) - Cu Slide 8 - the lateral vestibular nucleus forms the lateral vestibulospinal tract; the medial vestibular nucleus forms the medial vestibulospinal tract
19) - Cu Slide 4 - the two vestibulospinal tracts descend as part of the medial descending motor system
OTHER STUFF
TOPIC 4 - Corticobulbar pathways
20) - - gives the general idea
21) - FIGURE 8-26 - summarizes the situation for the various motor nuclei
22) - FIGURE 8-27 - deals with the facial nerve
23) -
TOPIC 5 - Brainstem reflexes
24) - FIGURE 8-28 - the gag reflex
25) - FIGURE 8-29 - the corneal reflex
TOPIC 6 - Clinical Cases
Case 19
PIX BRAIN HOME _ _ MODULE 12 HOME _ _ I WANT TO