Cranial Nerves Flashcards
How many pairs of cranial nerves are there?
- 12
Where do the cranial nerves emerge?
- along the longitudinal axis of the brain from anterior to posterior
Are cranial nerves part of the peripheral or central nervous system?
- peripheral nervous system
What are the sensory components of the PNS?
- somatic sensation (skin, muscles)
- special sensations (vision, etc.)
- visceral sensations (visceral organs)
What are the motor components of the PNS?
- somatic motor (skeletal muscles)
- autonomic motor (visceral organs)
What cranial nerve controls somatic sensory?
- CN V (trigeminal)
What cranial nerve controls special sensory?
- CN I (olfactory)
- CN II (optic)
- CN VII (facial)
- CN VIII (vestibularcochlear)
- CN IX (glossopharyngeal)
What cranial nerve controls visceral sensory?
- CN IX (glossopharyngeal)
- CN X (vagus)
What cranial nerve controls somatic motor?
- CN III (oculomotor)
- CN IV (trochlear nerve)
- CN V (trigeminal)
- CN VI (abducens)
- CN VII (facial)
- CN IX (glossopharyngeal)
- CN X (vagus)
- CN XI (accessory)
- CN XII (hypoglossal)
What cranial nerve controls autonomic motor?
- CN III (oculomotor)
- CN VII (facial)
- CN IX (glossopharyngeal)
- CN X (vagus)
What is olfaction?
- sense of smell
Where are the receptors that detect olfactory stimulation located?
- they line the superior portion of the nasal cavity
Where do the olfactory stimuli axons enter the skull?
- via the olfactory foramen and then synapse with neurons in the ipsilateral olfactory bulb
Where does the optic nerve emerge?
- the back of each eyeball
Where does the optic nerve enter the skull?
- the optic foramina
What is the optic chiasma?
- provides a site for the crossing over or desiccation of optic nerve fibers so that contralateral half of the visual field is perceived and processed by the visual cortex
Where do the axons continue after they cross the optic chiasma?
- continue posteriorly via the optic tracts and synapse with neurons in the thalamus
Where does the oculomotor nerve originate?
- in the midbrain
Where does the oculomotor nerve enter the orbit?
- superior orbital fissure of the sphenoid bone
What does the oculomotor nerve do?
- carries motor signals to some of the extrinsic eye muscles
- carries autonomic (parasympathetic) signals to intrinsic (smooth) eye muscles that
constrict the pupil and adjust the shape of the lens
Where does the trochlear nerve originate?
- in the midbrain
What does the trochlear nerve do?
- carries motor
signals to one of the extrinsic eye muscles
Where does the trochlear nerve enter the orbit?
- superior orbital fissure
Where does the abducens nerve originate?
- in the pons