Cranial nerves- lecture 3 Flashcards
typical spinal nerves contain what fibers
motor, sensory and post-ganglionic sympathetic fibers
the brain stem is a site for numerous ____ ____
parasympathetic nuclei
cranial nerves arise from ___ ___ and do not contain _____
brainstem and do not contain sympathetic fibers
how many pairs of cranial nerves
12
which two cranial nerves are not considered to be true nerves, but are instead consider ____
CN I and II, are considered tracts
how are cranial nerves numbered?
sequentially according to their origin cephalocaudally, CN I is the most cephalic and CN XII is the most caudal
the site where the cranial nerve attaches to the brain stem is known as the ___ ____
superficial origin
the more deeply situated group of neurons from which the fibers arise from is called the ___ ___
deep origin (motor nucleus) or deep termination (sensory nucleus)
what is the other name for CN I
olfactory nerve
where does CN I leave from?
through the cribriform of the ethmoid
what fibers does CN I contain
special sense of smell (olfaction)
what is the other name for CN II
optic n.
what does CN II leave through
optic canal
what fibers does CN II contain
special sense of sight (vision)
what is the other name for CN III
oculomotor n.
what does CN III leave through
superior orbital fissure (SOF)
what fibers does CN III contain
- motor to selected extraocular muscles: levator palpebrae, superioris, superior rectus, medial rectus, inferior rectus, inferior oblique
- parasympathetic to ciliary and sphincter pupillae muscles via the ciliary ganglion
what is the other name for CN IV
trochlear n.
what does CN IV leave through
SOF
what fibers does CN IV contain
motor to superior oblique extraocular muscle
what is the other name for CN V
trigeminal
what is different about CN V compared to the other nerves
it has 3 divisions, V1, V2, V3
what does CN V leave through
V1- SOF
V2- Foramen rotundum
V3- foramen ovale
what fibers does CN V contain
V1- sensory to the orbit and forehead
V2-sensory to the upper jaw and region
V3-sensory to the lower jaw and region; anterior 2/3 of the tongue (general sensation) and motor to the muscles of mastication, tensor palati, anterior belly of digastric, mylohyoid
what is the other name for CN VI
Abducens n.
what does CN VI leave through
SOF
what fibers does CN V1 contain
motor to the lateral rectus extraocular muscle
what is the other name for CN VII
facial n.
what does CN VII leave through
internal auditory meatus–>intraosseos pathway–>stylomastoid foramen
what fibers does CN VII contain? these are the fibers in the actual facial n, not its branches
- motor to muscles of facial expression, stylohyoid, posterior belly of digastric, stapedius
- special sense of taste fibers to anterior 2/3 of tongue
- parasympathetic to sublingual and submandibular glands via submandibular ganglion; parasympathetic to lacrimal gland via pterygopalatine ganglion
- sensory sensation from the skin of the external auditory meatus
what is the other name for CN VIII
vestibulochochlear n.
what does it CN VIII leave through
internal auditory meatus
what fibers does CN VIII contain
special senses of hearing, balance, and acceleration
what is the other name for CN IX
glossopharyngeal n.
what does CN IX leave through
jugular foramen
what fibers does CN IX contain
- motor to stylopharyngeus m.
- sensation from the external ear, sensation from carotid sinus/body, pharynx, and middle ear
- parasympathetic to parotid gland via otic ganglion
- special sense of taste posterior 1/3 of tongue
what is the other name for CN X
vagus n.
what does CN X leave through
jugular foramen
what fibers does CN X contain
- parasympathetic to thorax and abdomen
- motor to pharynx, larynx, soft palate (except for tensor palati), upper 2/3 of esophagus
- visceral sensation (sensory) from larynx, trachea, bronchi, heart, esophagus, digestive tract up to mid transverse colon
- special sense of taste from epiglottis and palate
- general sensation from auricle, external acoustic meatus
what is the other name for CN XI
accessory n.
what does CN XI leave through
jugular foramen
what fibers does CN XI contain
motor to the SCM and trapezius m.
what is the other name for CN XII
hypoglossal n.
what does CN XII leave through
hypoglossal canal
what fibers does CN XII contain
motor to muscles of the tongue (except for palatoglossus)
all autonomic ganglia in the head are ____
parasympathetic (COPS)
what are the parasympathetic ganglia of the head
- ciliary
- pterygopalatine
- submandibular
- otic
preganglionic parasympathetic fibers reach their target ganglia via branches of ___ ___ ___
CN III, CN VII, or CN IX
post-ganglionic parasympathetic fibers reach their end organs by hitch-hikinh along branches of ____
CN V- the different divisions
preganglionic sympathetic fibers arise in ____
T1-T4
post-ganglionic sympathetic fibers arise from the _____ and reach their target end organs how
superior cervical ganglion and reach their target organs via branches of the internal and external carotid aa.
CN III goes to which ganglion? which then goes where to do what?
ciliary ganglion, which then synapses on the postganglionic fiber and it hitches a ride on V1 to go to the orbit and constrict the pupil
a post ganglionic fiber goes through the ciliary ganglion to do what
to dilate the pupil
CN VII goes to which ganglion to do what
goes to two ganglions, pterygopalantine and submandibular
- synapses on postganglionic fibers, hitches a ride on V2 and V3 respectively
- fiber from pterygopalantine goes to lacrimal gland and palate
- fiber from submandibular goes to sublingual gland, submandibular gland and floor of mouth
a postganglionic sympathetic fiber goes through the pterygopalantine ganglion to get where
lacrimal gland and palate
what ganglion does CN IX go to and what does it do
goes to the otic ganglion, synapses on postganglionic fiber, hitches a ride on V3, and goes to parotid gland and vestibule of the mouth
-parotid gland is the salivary gland that is activated when you are chewing something tough
CN 1 is purely sensory for what
smell
what comprises the actual CN I nerve
axons from bipolar neurons of the olfactory epithelium of the nasal cavity
the axons that form the olfactory n. pass from the nasal cavity up into the cranial cavity through holes in the ____________
cribriform plate of the ethmoid bone, located on either side of the crista galli
the axons of the olfactory nerve pass through the cribriform plate in groups called what
filia olfactoria
what do the filia olfactoria enter
the olfactory bulb that lies just above the perforated cribriform plate
what is it called when you lose your sense of smell and what is the most common way for this to happen
anosmia; nerve is most easily torn in trauma and CSF will drip from the nose
what nerve is purely sensory for vision and where does it extend
optic nerve and it is really a brain tract that extends from the eye through the optic canal to form the optic chiasm
what is the purpose of the optic chiasm
the union allows the excitatory stimuli from one retina to pass to the opposite side of the brain for interpretation
what does the optic nerve pass through?
optic foramen, it is the only nerve that doesn’t use the SOF to get into the orbit
what does the oculomotor nerve supply
all the extraocular mm. except for the lateral rectus (LR6) and the superior oblique (SO4)
remember clue: (LR6SO4)^3, means that the rest of the extraocular muscles are supplied by CN III but LR is supplied by CN VI and SO is supplied by CN IV
parasympathetic supply of CN III
it supplies the sphincter pupillae and ciliary mm. via the ciliary ganglion
sympathetic innervation to the sphincter pupillae and ciliary mm.
reaches these targets by hitch hiking along the ophthalmic division of the trigeminal (CN V1)- specifically the nasociliary n.
the superior division of CN III supplies what muscles
superior rectus and levator palpebrae mm.
the inferior division of CN III supplies what muscles
medial rectus, inferior rectus, and inferior oblique mm.
preganglionic parasympathetic fibers travel in the ____ ____ of CN III and then pass to the ciliary ganglion
inferior division of CN III
Postganglionic sympathetic fibers travel directly to the eye via the ___ ___ nerve or to the nasocilary branch of V1 and then into the ___ ___ nn.
short ciliary nn; long ciliary nn.
