Oculomotor CNIII Flashcards
What is the fiber type(s) of the oculomotor nerve?
Motor: General Somatic Efferent and General Visceral Efferent
The cell bodies of the oculomotor nerve lie in the _____.
Oculomotor nuclear complex
Where is the oculomotor nuclear complex located?
Ventral to the cerebral aqueduct at the level of the superior colliculus (midbrain)
The fibers of the oculomotor nerve course through the _____ and emerge into the _____. They course through the _____ and then enter the orbit via the _____.
Midbrain tegmentum; interpeduncular fossa/cistern;cavernous sinus; superior orbital fissure
The nuclear complex consists of the _____ and _____
Edinger-Westphal nucleus and Oculomotor nucleus
Edinger-Westphal nucleus has what kind of fibers types?
Preganglionic parasympathetic and postganlionic
Edinger-Westphal nucleus: Preganglionic parasympathetic cell bodies send fibers (most superficial in the nerve) to the _____ in the orbit. From here the postganglionics course to the smooth muscles of _____ (lens thickening) and _____ muscle of the iris (pupillary constriction)
Ciliary ganglion; ciliary body; sphincter pupillae
Oculomotor nucleus consists of individual _____ for each muscle.
Subnuclei
The axons of the oculomotor nucleus project to the _____ skeletal muscles of the eye.
Extraocular
What are all the extraocular muscles of the eye innervated by the oculomotor nucleus? (4) Which muscle is the only skeletal muscle innervated by this nerve that is NOT extraocular?
Superior rectus m. Medial rectus m. Inferior rectus m. Inferior oblique m. NOT: Levator palpebrae superioris m.
What is the action of Superior rectus m. ?
Elevation of the eyeball
What is the action of Medial rectus m. ?
Adduction of the eyeball
What is the action of Inferior rectus m.
Depression of the eyeball
What is the action of Inferior oblique m. ?
Excyclotorsion (Outward rotation)
What is the action of Levator palpebrae superioris m. ?
Raise upper eyelid
What is the clinical relevance if there is an lesion on Levator palpebrae superioris m. ?
Ptosis: Drooping of the eye/ Upper eyelids drop
What is Lateral/external strabismus, and what cause this?
Deviation due to unopposed Lateral rectus m. and Superior oblique m.
What is Diplopia?
Double vision
What are the 2 muscles that Edinger-Westphal innervate?
Sphincter pupillae m. and Ciliary m.
What is the action of sphincter pupillae m.? What type of muscle is this?
Pupil constriction; Smooth muscle (Parasympathetic)
What is Mydriasis and what is the cause?
Dilated pupil and light sensitive; dysfunctional sphincter pupillae m. (Parasympathetic)
What is Cycloplegia and what is the cause?
Paralysis of ciliary m. Loss of near response (Eyes cannot focus on nearby objects)
The nucleus of the Oculomotor N. ( both Edinger-Westphal and Oculomotor) are located where?
Tegmentum of rostral midbrain
Specifically, what is the fiber classification of Edinger-Westphal?
General Visceral Efferent (Smooth muscle)
Specifically, what is the fiber classification of Oculomotor nerve?
General Somatic Efferent (Skeletal muscles)
What types of nerve fibers are carried in Edinger-Westphal?
Parasympathetic
In general, what are the function of oculomotor nerve?
- Eyelid and eyeball movement
- Controls muscles responsible for the precise movement of eyes or visual tracking or fixation of objects.
- Adjust the amount of light entering the eye
- Adjust focus
- Changes pupil and lens shape
