lecture 14 cranial nerves and autonomic nervous system for exam 3

how many pairs of cranial nerved are there?

12

which cranial nerves do not have somatic motor components?

CN I, II and VIII

which cranial nerves comprise part of the parasympathetic division of the autonomic nervous system?

CN III, VII, IX and X

CN I

olfactory nerve

is the olfactory nerve sensory, motor and both?

sensory only

where do olfactory receptor cell axons travel from?

from the nasal mucosa through the cribriform plate and synapse on neurons in the olfactory bulb.

what are cell axons?

the elongated portion of the neuron located in the center of the cell between the soma and axon terminals

CN II

optic nerve

is the optic nerve, sensory, motor, or both?

sensory only

what axons form the optic nerve?

axons of retinal neurons

how do axons enter the skull for the optic nerve?

via the optic canal

Half of the axons cross at the ——-; axons continue as the optic tract to the ————- in the ——-

optic chiasm, thalamus and synapse, lateral geniculate nucleus

LGN axons project to the primary visual cortex in the —-

occipital lobe

CN III

oculomotor nerve

is the oculomotor nerve sensory, motor or both?

motor only

where do axons emerge from and exit for the oculomotor nerve?

emerge from the midbrain and exit the skull through the superior orbital fissure

how many muscles does the oculomotor never innervate?

5 (medial rectus, superior rectus, inferior rectus, inferior oblique, levator palpebrae)

Parasympathetic axons that originate from neurons of the dinger-westphal nucleus are part of what nerve?

oculomotor

what do the parasympathetic axons of the oculomotor nerve target?

the ciliary ganglion behind the eye

what muscles do the postganglionic neurons in the ciliary ganglion innervate?

the pupillary constrictor muscles as well as the ciliary body

CN V

trigeminal nerve

is the trigeminal nerve sensory, motor or both?

both sensory and motor

where does the sensory nerve emerge from?

the pons

how many divisions does the trigeminal nerve have?

3 divisions

V1 of trigeminal nerve

ophthalmic nerve

where does the ophthalmic nerve of the trigeminal nerve get its information and enter the skull?

receives sensory information from the upper face and enters the skull via the superior orbital fissure

V2 of trigeminal nerve

maxillary nerve

where does the maxillary nerve of the trigeminal nerve get its information from and how does it enter the skull?

receives sensory information from the middle part of the face/nose as well as the upper teeth and enters the skull via foramen rotundum

where does the mandibular nerve carry motor fiber to?

the 4 muscles of mastication, the 4 muscles of the neck, palate and ear

V3 of the trigeminal nerve

Mandibular nerve

where does the mandibular nerve get information from and how does it enter the skull

the lower face and lower teeth and anterior 2/3 of tongue. the axons enter the skull through the foramen ovale

where do all 3 divisions of the trigeminal nerve relay?

in the thalamus

where do all 3 division of the trigeminal nerve project?

projecet to the somatosensory cortex where the face and tongue are respresented

CN VI

abducens nerve

where do axons originate ans exit in the abducens nerve?

from pons to the skull through the superior orbital fissure

what does the abducens nerve target?

the lateral rectus

CN VII

facial nerve

is the abducens nerve sensor, motor, or both?

motor only

is the facial nerve sensory, motor, or both?

both sensory and motor

what sensations do facial axons carry and where?

sensory axons carry taste sensation from anterior 2/3 of the tongue and enter the cranium via the internal acoustic meatus.

where do motor axons of the facial nerve exit?

motor axons from the pons exit the skull through the stylomastoid foramen

what muscles does the facial nerve innervate?

innervates the muscles of facial expression, 2 suprahyoid muscles and the stapedius muscles

do parasympathetic nerves travel with the facial nerve?

yes

what do the parasympathetic fibers of the facial nerve target?

either the pterygopalatine or submaandibular ganglion

what do the postganglionic fibers of the facial nerve reach?

the glands of the nasal cavity, lacrimal glands or the submandibular and sublingual salivary glands

CN VIII

vestibulocochlear/acoustic nerve

is the vestibulocochlear/acoustic nerve sensory, motor or both?

sensory only

what does the vestibulocochlear/acoustic nerve carry?

special sensory information for hearing and vestibulation

where does the vestibulocochlear/acoustic nerve for hearing and vestibulation originate from?

for hearing, from the cochlea and for vestibulation, from the semicircular canals to the pons.

how do axons of the vestibulocochlear/acoustic nerve enter the cranium?

through the internal acoustic meatus

what do auditory fibers synapse with, where, and what do the cells project to?

synapse with neurons in the medial geniculate nucleus of the thalamus and the cells project to the primary auditory cortex

CN IX

glossopharyngeal nerve

is the glossopharyngeal nerve sensory, motor, or both?

both sensory and motor

what does the glossopharyngeal nerve carry?

carriers general sensory and taste information from the posterior 1/3 of the tongue and pharynx and carries motor information to the stylopharyngeus

how do axons of the glossopharyngeal nerve leave the skull?

through the jugular foramen

CN X

vagus nerve

is the vagus nerve sensory, motor, or both?

both sensory and moto

what info does the vagus nerve carry?

carries sensory information from the neck, thorax and abdomen and pelvis.

what do the motor axons of the vagus nerve target?

muscles of palate, pharynx, tongue and larynx

how do axons enter and leave skull for vagus nerve?

through jugular foramen

do preganglionic axons run with the vagus nerve?

yes

what do the preganglionic axons of the medulla for the vagus nerve do?

contact numerous terminal ganglia throughout the thorax, abdomen and pelvis

what do postganglionic axons of the vagus nerve do?

innervate wide array of peripheral target including heart, lungs, digestive tract and smooth muscle lining numerous blood vessels

CN XI

spinal accessory nerve

is the spinal accessory nerve sensory, motor or both?

motor only

where are neurons of the spinal accessory nerve located and how to they enter/leave the skull?

located in the cervical spinal cord and send axons which ascend to enter skull through foramen magnum and exit through the jugular foramen.

what muscles do the axons of the spinal accessory nerve innervate?

the sternocleidomastoid and trapezius muscles

CN XII

hypoglossal nerve

is the hypoglossal nerve sensory, motor or both?

motor only

where do axons of the hypoglossal nerve enter and exit the skull?

from neurons in the medulla and exit through the hypoglossal canal

what muscles does the hypoglossal nerve innercate?

tongue muscles

what does the autonomic nervous system (ANS) do?

functions to regulate the internal environment and maintain equilibrium/homeostasis

what are the targets of the autonomic nervous system?

smooth muscles, cardiac muscle and glands

digestion function of autonomic nervous system

regulates GI tract mobility

functions of autonomic nervous system

blood pressure, sweat/salivary gland activity, pupillary diameter, airway diameter, adrenal gland function, urination, defecation and sexual function.

divisions of autonomic nervous system

sympathetic and parasympathetic

sympathetic division origin

thoracolumbar origin of preganglionic axons

what does the sympathetic division of the autonomic nervous system target?

T1 to L2

parasympathetic division origin

craniosacral origin of pre-ganglionic axons

what does the para sympathetic division of the autonomic nervous system target?

CN III, VII, IX and X plus S2-S4

what does the sympathetic division respond to?

needs requiring the mobilization of resources aka fight or flight emergencies

what opposes the sympathetic division?

the parasympathetic division

most organs receive input from ——

both divisions

anatomy of ANS outputs involves a —- neuron chain

two neuron chain

where is the axon of a preganglionic neuron located?

either in the spinal cord or brainstem

where is the axon of a postganglionic cell located?

in one of various peripheral ganglia

where are the preganglionic neurons of the sympathetic division located?

in the lateral horn of the spinal cord (between T1-L2)

intermediolateral cell column

T1-L2

where are the postganglionic neurons of the sympathetic division located?

in the peripheral ganglia adjacent to the vertebral column

sympathetic trunk

the chain of ganglia extends from the cervical region to the base of the coccyx on the ventrolateral side of the vertebral column. The ganglia are connected to spinal nerves by small branches called rami communicans; they are also connected to the ganglia above and below.

prevertebral ganglia

ganglia located anterior to vertebral column

what are the 3 pairs of the prevertebral ganglia?

celiac, superior mesenteric and inferior mesenteric

a preganglionic axon can take of on how many cources?

4

course 1 that a preganglionic axon can take

Establish synaptic contact with a postganglionic neuron at the same segmental level.

course 2 that a preganglionic axon can take

Travel up or down the sympathetic trunk before establishing synaptic contact with a postganglionic neuron at a different level.

course 3 that a preganglionic axon can take

Pass thru the sympathetic trunk to reach a postganglionic neuron in any of the 3 prevertebral ganglia

course 4 that a preganglionic axon can take

Pass thru the sympathetic trunk and target the adrenal medulla, which when stimulated releases adrenaline (epinephrine) into the bloodstream

rami communicans can either be —- or —-

white or gray

white rami

always axons of sympathetic preganglionic neurons (myelinated)

gray rami

axons of postganglionic neurons (unmyelinated)