cranial nerves Flashcards
the cranial nerve nuclei
- each nucleus has a single function
- location of nucleus in brain stem follows organization of neural tube
somatic efferent column includes what 4 nuclei?
- hyoglossal nucleus
- abducens nucleus
- trochlear nucleus
- oculomotor nuclei
somatic efferent column nuclei order of ascending the brain stem
caudal > rostral
hypoglossal > abducens > trochlear > oculomotor
hypoglossal nucleus function
- controls intrinsic and extrinsic muscles of the tongue
where do the hypoglossal nucleus axons exit?
between the pyramid and inferior olive and join in to make CN XII (12)
signs and symptoms of hypoglossal nerve lesion
- paralysis of ipsilateral half of the tongue
- on protrusion, tongue deviates to side of lesion (unopposed action of genioglossus muscle)
- atrophy and fasciculations
hypoglossal nucleus location and shape
- in the medulla
- spherical/dome shaped
- alpha motor neurons innervating the tongue
abducens nucleus location and shape
- in caudal pons
- spherical
what does the abducens nucleus control?
- lateral rectus muscle
where does the abducens nucleus axons exit?
attached at junction of pons and medulla and in CN VI (6)
signs and symptoms of lesion on CN VI (abducens nucleus)
- medial strabismus
- diplopia
- inability to abduct eye
trochlear nucleus location
caudal midbrain
what does the trochlear nucleus control?
- superior oblique muscles
where do the trochlear nucleus axons exit?
- CN IV (4)
- CN IV leaves on dorsal side of brain stem and decussates
signs and symptoms of lesion on CN IV (trochlear)
- limitation of downward gaze when looking medially
- postural adjustments
oculomotor nuclei location
rostral midbrain
what does the oculomotor complex contain? what do they control?
- subnuclei that control medial rectus, superior rectus, inferior rectus, and inferior oblique muscles
- subnucleus that controls levator palpebrae superior
where do the oculomotor complex axons exit?
from interpeduncular fossa into CN III (3)
signs and symptoms of a lesion on CN III (oculomotor complex)
- eye is down and out
- ptosis (drooping of eyelid)
general visceral efferent column includes…
- dorsal motor nucleus of the vagus
- salivatory nuclei (inferior and superior)
- Edinger-westphal nucleus
location of dorsal motor nucleus of X
in medulla, ventral to 4th ventricle
what is the dorsal motor nucleus of X and what does it do?
- preganglionic parasympathetic fibers
- supply heart, lungs, stomach, and intestine
where do the dorsal motor nucleus of X axons exit and synapse?
exit: CN X
synapse: in parasympathetic ganglia of organs innervated
inferior salivatory nucleus location
dorsal pons
what is the inferior salivatory nucleus and what does it do?
- preganglionic parasympathetic (visceral) fibers
- supplies parotid gland
where do the inferior salivatory nucleus axons exit and synapse?
exit: CN IX
synapse: otic ganglion
superior salivatory nucleus location
rostral medulla, cannot be easily identified
what is the superior salivatory nucleus and what does it do?
- preganglionic parasympathetic fibers
- supply sublingual, submandibular, and lacrimal glands
where do the superior salivatory nucleus axons exit and synapse?
exit: CN VII (7)
synapse: sphenopalatine and submandibular ganglia
Edinger-westphal nucleus location
in the heart of oculomotor complex, this is the only portion that is visceral efferent
what is the Edinger-westphal nucleus and what does it do?
- preganglionic parasympathetic fibers
- supply ciliary muscle and iris constrictor
where do the Edinger-westphal nucleus axons exit and synapse?
exit: CN III
synapse: ciliary ganglion
what does the visceral afferent column include?
- nucleus solitarius
nucleus solitarius location
in medulla
where do axons enter from in nucleus solitarius?
- enter from CN VII, IX, X
what does the nucleus solitarius do/have?
- special visceral afferents (taste)
- general visceral afferents (carotid sinus, carotid body, gut)
- nucleus and tract
general somatic afferent column includes…
- descending nucleus of V (pain and temperature)
- principal nucleus of V (fine touch)
- mesencephalic nucleus of V (proprioceptive afferents)
the descending nucleus of V receives projections from …?
CN: V, VII, IX, and X
- these nerves send pain info
descending nucleus of V characteristics..?
- pain and temperature sensation from head and face
- has tract and nucleus
- analog of zone of lissauer and substantia gelatinosa of spinal cord
- projects to ventral posterior medial (VPM) of thalamus
Principal (chief) nucleus of V receives projections from
CN
- V
- VII
- IX
- X
Principal (chief) nucleus of V characteristics?
- touch, pressure, and vibration sensation from head and face
- analog of dorsal column nuclei
- projects to VPM of thalamus
mesencephalic nucleus of V has axons in…
CN V
mesencephalic nucleus of V characteristics?
- has cell bodies of pseudo-unipolar neurons form this nucleus
- spindle and joint afferents related to mastication
- projects to cerebellum (superior peduncle)
- includes tract and nucleus
- analog to spinocerebellar pathways
- adjusts force and direction of movement as well as timing of the mouth and chewing
special visceral efferent column include
- nucleus ambiguus
- facial nucleus
- motor nucleus of V
- accessory nuclei
nucleus ambiguus axons exit..
in CN X and IX
nucleus ambiguus innervate muscles of the…
pharynx and larynx
what is the nucleus ambiguus responsible for?
- swallowing
- phonation
location of nucleus ambiguus?
somewhere between inferior cerebellar peduncle and the inferior olive
signs and symptoms of lesion on CN IX
- ipsilateral pareisis (weak voluntary mvmt) of pharynx
- gag reflex can not be elicited
signs and symptoms of lesion on CN X
- ipsilateral pareisis of soft palate and difficulty swallowing
- hoarseness
facial nucleus axons exit…
CN VII
facial nucleus innervates…
muscles of facial expression (frontalis, orbicularis, oculi, orbicularis oris)
motor nucleus of V axons exit
CN V (mandibular division)
motor nucleus of V innervates…
muscles of mastication (masseter, temporalis, external and internal pterygoid)
- receives crossed and uncrossed corticobulbar fibers
accessory nuclei have cell bodies located:
in ventral horns C2-C5
accessory nuclei exit
in CN XI
accessory nuclei innervate…
trapezius and sternocleidomastoid muscles
each nerve has ___________ function(s) and each nucleus has ___________ function(s)
multiple, one
in the neural tube, the…
____________ plate contains ________ nuclei and the ___________ plate contains _______ nuclei
alar, sensory
basal, motor
- correspond with dorsal ventral
as you ascend the spinal cord to the brain, the neural tube gets divided.
the alar/dorsal is split into __________ and _________ sensory.
the basal/ventral is split into ____________ and ___________ motor
(put in order from dorsal to ventral)
somatic, visceraI
visceral, somatic
in the brain, visceral is part of the ____________ nervous system
parasympathetic
visceral motor has…
parasympathetic nuclei
visceral means
autonomic
so therefore… visceral sensory and visceral motor are…
parasymphathetic autonomic sensation and movement (unconscious)
4 columns of nuclei include:
- somatic afferent
- visceral afferent
- visceral efferent
- somatic afferent
cranial nerves that are devoted to special sensory input?
CN I, II, and VIII
cranial nerves that are devoted to eye movement and pupillary constriction?
CN III, IV, and VI
cranial nerves that are devoted to pure motor? what muscles do they control?
CN XI and XII
XI = sternocleidomastoid and trapezius muscles
XII = muscles of tongue
cranial nerves that are mixed?
CN V,VII, IX, and X
cranial nerves that are parasympathetic fibers?
CN III, VII, IX, and X
what are special visceral efferent column derived from?
gill arches (evolution of the head)
why are pharyngeal arches important?
cranial nerves develop from there during development
facial nucleus is located in
the pons
motor nucleus of V location
ventral to the principal (chief) nucleus of V (between 4th ventricle and inferior olive)
location of principal (chief) nucleus of V
dorsal to motor nucleus of V (between 4th ventricle and inferior olive)
cranial nerve XII is also known as
the hypoglossal nerve
hypoglossal nerve (CN XII) is formed by and exits?
numerous fascicles that exit the medulla between the pyramid and the olive
cranial nerve XI is also known as
the accessory nerve
accessory nerve (CN XI) pathway
- origin: 5 upper cervical segments of the spinal cord
- ascends: into the skull through the foramen magnum
- exits: brainstem (medulla) lateral to inferior olive
cranial nerve X is also known as
the vagus nerve
the vagus nerve (CN X) originates:
- as numerous fascicles
- fascicles are attached lateral to the inferior olive
what does the vagus nerve innervate?
internal structures including:
- heart
- lungs
- stomach
- small intestine
also provides parasympathetic innervation to the visceral organs
cranial nerve IX is also known as
the glossopharyngeal nerve
the glossopharyngeal nerve (CN IX) originates:
- as fascicles emerging lateral to the inferior olive (medulla) to the pharynx
- superior to CN X
the glossopharyngeal nerve controls
- motor and sensory innervation to the pharynx and larynx
- autonomic and visceral sensory innervation to the cardiovascular and respiratory structures
- parasympathetic to the parotid glands
- afferent taste information from post. 1/3 of tongue
cranial nerve VIII is also known as
the vestibulocochlear nerve
the vestibulocochlear nerve location
attaches to brainstem at cerebellopontine angle rostral to CN IX
what are the 2 parts of vestibulocochlear nerve (CN VIII)
- acoustic division
- vestibular division
the acoustic divistion of CN VIII
- carries auditory sensation from the ear
the vestibular division of CN VIII
carries equilibrium sensations from the labyrinth of the inner ear
cranial nerve VII is also known as
the facial nerve
facial nerve location
adjacent to CN VIII at the junction of the pons and medulla
2 roots of the facial nerve (CN VII)
- larger = motor
- smaller = sensory and motor
the facial nerve (CN VII) is parasympathetic to:
- lacrimal glands
- salivary glands
the facial nerve (CN VII) is sensory to:
the anterior 2/3 of the tongue
the facial nerve (CN VII) is motor to:
muscles of facial expression
cranial nerve XI relates to:
gustatory (taste) information
cranial nerve V is also known as
the trigeminal nerve
where does the trigeminal nerve emerge?
on the ventrolateral surface of the pons
the trigeminal nerve (CN V) has 3 branches:
- opthalamic (V1)
- maxillary (V2)
- mandibular (V3)
the trigeminal nerve is a mixed nerve and carries what signals to where?
- sensory info from the structures of the head and neck
- motor signals to the muscles of mastication
opthalamic (V1) branch and the maxillary branch (V2) carry ___________ information
sensory
the mandibular (V3) branch carries ____________ & ___________ information
sensory and motor
cranial nerve VI is also known as
the abducens nerve
the abducens nerve is located:
attached at the junction of the pons and medulla medially
the abducens nerve innervates:
lateral rectus muscle
cranial nerve IV is also known as
the trochlear nerve
the trochlear nerve location:
- exits from the dorsal aspect of the brainstem
what is unique to the trochlear nerve (CN IV)?
- it is the only CN where all of its axons decussate
- has the longest intracranial course
the trochlear nerve innervates:
the superior oblique muscle
cranial nerve III is also known as
the oculomotor nerve
the oculomotor nerve location:
emerges from the interpeduncular fossa
what is unique about oculomotor nerve (CN III)?
it has 2 nuclei
the oculomotor nerve (CN III) controls:
- motor innervation of 4 of the 6 extraocular muscles that control eye movement
- motor innervation to levator palpebrae superiosis
- parasympathetic to the ciliary and pupillary constrictor muscles
cranial nerve II is also known as
the optic nerve
the optic nerve carries
- sensual information
- visual sensation
what is unique about the optic nerve?
- the nerves from both eyes undergo partial decussation in the optic chiasm
- fibers representing the nasal half of the retina in each eye cross to the contralateral side
cranial nerve I is also known as
the olfactory nerve
the olfactory nerve (CN I) is responsible for
sense of smell
location of olfactory nerve
- originates at the olfactory epithelium of the nose
- then pierce the cribriform plate of the ethmoid bone
- synapse to the olfactory bulb
what is the olfactory bulb?
the elongated olfactory tract to comprise CN I
