CLASS DISCUSSION
Module 9
It should be apparent that Module 9 is the rare short one. It deals only with the nuclei and cranial nerves associated with the somatic efferent cell column. Since three of the four cranial nerves in this group innervate extraocular muscles, the module is mainly concerned with eye movement. The fourth, the hypoglossal, innervates the muscles of the tongue. The oculomotor has a general visceral efferent (parasympathetic) component, but the other three are pure somatic motor nerves.
TOPIC 1 - The somatic efferent cell column
1) - FIGURE 9-1 - This view shows the cell column and gives you a way to call up individual slides. Because of the angle of our slides, you often have to click through several of them to trace exiting fibers as they leave their nucleus and migrate through the brainstem to their point of exit. Try the following:
_____ For the oculomotor, start at slide 22 and keep clicking "rostral" to slide 27.
_____ For the trochlear, start at slide 21 and keep clicking "caudal" to slide 16.
_____ For the abducens, look at slide 11.
_____ For the hypoglossal, look at slide 5
TOPIC 2 - Course of the nerves, once they exit from the brainstem. The hypoglossal just passes laterally and exits through the hypoglossal canal. The story is more complex for the others. They all ultimately exit from the cranial cavity by passing through the cavernous sinus together, and then through the superior orbital fissure to enter the orbit. However the way they get to the cavernous sinus differs, from one nerve to the next.
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TOPIC 3 - Action of the extraocular muscles
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TOPIC 4 - The Clinical Cases.
Case 19 -
Case 20 -