Lectures 2 & 3: Cranial Nerves Flashcards
Where are the nuclei of cranial nerve III-XII?
Brainstem
What are the cranial nerves?
1: Olfactory
2: Optic
3: Oculomotor
4: Trochlear
5: Trigeminal
6: Abducens
7: Facial
8: Auditory: vestibular/cochlear
9: Glossopharyngeal
10: Vagus
11: Spinal accessory
12: Hypoglossal
What can a cranial nerve do?
Function solely for sensation or motor
Function as a combination of sensory, motor, and autonomic
What nerves function as sensory only?
I, II, VIII
What nerves function as motor only?
III, IV, VI, XI, XII
What nerves function as mixed sensory and motor?
V, VII, IX, X
What nerves function as autonomic?
III, VII, IX, X
What are the general somatic sensory/afferent nerves?
5, 7, 9, 10
What are the special somatic sensory/afferent nerves?
2, 8
What are the special somatic sensory/afferent nerves responsible for?
Sight and hearing
What are the general visceral sensory/afferent nerves?
7, 9, 10
What are the special visceral sensory/afferent nerves?
1, 7, 9, 10
What are the special visceral sensory/afferent nerves responsible for?
Smell and taste
What are the general somatic motor/efferent nerves?
3, 4, 5, 6, 7, 9, 10, 11, 12
What are the general visceral motor/efferent nerves?
3, 7, 9, 10, (+/-) 11
Which nerve does sensation to the face?
5
Which nerves share the solitary tract and nucleus?
7, 9, 10
Which nerves share nucleus ambiguus?
9, 10, 11
What is the olfactory nerve made of?
Biopolar neurons
How are the bipolar neurons replaced?
Stem cells
Where does the olfactory nerve come from?
Olfactory mucosa and vomeronasal organ
What is special about the pathway between the olfactory mucosa and vomeronasal organ?
It is the only pathway that does not pass through the thalamus
What does the olfactory nerve pass through?
Cribriform plate
What is the synapse of the olfactory nerve on?
Olfactory bulb neurons
What happens when the olfactory nerve hits the olfactory bulb neurons?
Send axons caudally via lateral and medial olfactory tract
Where does the olfactory nerve terminate?
In the piriform lobe for olfactory perception and hypothalamus OR reticular formation for behavior and emotion
Is the optic nerve an actual nerve?
Not technically. It is truly a tract
Since the optic nerve is truly a tract and not a nerve, the myelin is placed by which cell?
Oligodendrocytes
What axons come together to form the optic nerve?
Rods (night vision) and cones (color vision)
How does the optic nerve enter the skull?
Via optic foramen and canal
What forms the optic chiasm?
Right and left optic nerve come together in front of hypophysis
What percentage of the optic nerve decussates (cross to the other side) and becomes the optic tract in primates?
50%
What percentage of the optic nerve decussates (cross to the other side) and becomes the optic tract in cats?
65%
What percentage of the optic nerve decussates (cross to the other side) and becomes the optic tract in dogs?
75%
What percentage of the optic nerve decussates (cross to the other side) and becomes the optic tract in ungulates?
80-90%
What percentage of the optic nerve decussates (cross to the other side) and becomes the optic tract in fish?
100%
What does the optic nerve become once it crosses to the other side?
Optic tract
What is the post chiasm pathway?
Optic tract to lateral geniculate nucleus in the thalamus OR optic tract to midbrain for reflex pathways
What type of species have more laterally placed eyes? Why?
Prey
Giving them a wide field of view
Greater percentage of fibers decussating at the chiasm
Poor binocular vision
What is the vision of predators like?
Smaller field of view
Better binocular vision due to decrease decussation
What cranial nerves control the extra-ocular muscles?
3, 4, 6
What muscles does cranial nerve 3 (oculomotor) innervate?
Dorsal, medial, ventral recti
Ventral oblique
What muscle does cranial nerve 4 (trochlear) innervate?
Dorsal oblique
What muscles does cranial nerve 6 (abducens) innervate?
Lateral rectus
Retractor bulbi
What are the 2 nuclei of the oculomotor nerve?
Oculomotor motor nucleus and parasympathetic nucleus of CN3 in the midbrain
Where does the oculomotor go through the skull?
Orbital fissure
What are the 2 parts of the oculomotor nerve?
Somatic motor and parasympathetic motor
What muscles does the somatic oculomotor nerve innervate?
Levator palpable superioris Dorsal rectus Medial rectus Ventral rectus Ventral oblique