intro to cranial nerves Flashcards
CN I
oflactory
CN II
optic
CN III
oculomotor
CN IV
trochlear
CN V
trigeminal
CN VI
abducens
CN VII
facial
CN VIII
vestibulocochlear
CN IX
glossopharyngeal
CN X
vagus
CN XI
accessory
CN XII
hypoglossal
general
associated with a large area (body wall and limbs or viscera)
special
associasted with one organ or area (special sense)
somatic
striated muscle derived from somites
visceral
associated with GI tract either striated muscle derived from branchial arches or parasympathetic to smooth muscle and glands
afferent
sensory (impulse conduction toward brain)
efferent
motor (impulse conduction from brain)
afferents
GSA
GVA
SSA
SVA
general somatic afferent (GSA)
touch, temperature, pressure, pain, proprioception from body wall and limbs
general visceral afferent (GVA)
temperature, pressure, pain from viscera (GI tract)
special somatic afferent (SSA)
vision, hearing, balance
special visceral afferent (SVA)
smell, taste (the “chemical senses”, relating to eating)
efferents
GSE
SVE
GVE
general somatic efferent (GSE)
to striated muscles derived from somites = muscles of the eye (extraocular muscles) and the tongue
special visceral efferent (SVE)
to striated muscles dervied from branchial arches = muscles involved in eating and swallowing except for the tongue (i.e. muscles of facial expression, mastication, pharynx, and larynx)
general visceral efferent (GVE)
preganglionic parasympathetic fibers to smooth muscle and glands
mastication
arch 1, V3
facial expression
arch 2, VII
pharyngeal muscle
arch 3, IX
muscles of pharynx and larynx
arch 4, X
telencephalon
cerebrum (olfactory nerve, I)
dicenphalon
optic nerve, II
mesencephalon
midbrain (oculomotor, III, and trochlear, IV)
metencephalon
cerebellum
pons (trigeminal, V)
myelencephalon
pons-medulla junction (abducens, VI; facial, VII; vestibulocochlear, VIII)
medulla (glosopharyngeal, IX; Vagus, X; accessory, XI; hypoglossal, XII)
cranial nerve attachments to midbrain
III, IV
cranial nerve attachments to pons
V
cranial nerve attachments to pons - medulla junction
VI, VII, VIII
cranial nerve attachments to medulla
IX, X, XII
cranial nerve attachments to spinal cord
XI
cribiform plate
CN I
optic canal
CN II
sup. orbital fissure
CN III, IV, V1, VI
foramen rotundum
CN V2
foramen ovale
CN V3
interal auditory meatus
CN VII, VIII
jugular foramen
CN IX, X, XI
hypoglossal canal
CN XII
olfactory nerve
consists of numerous bundles of unmyelinated axons from bipolar neurons in the nasal mucosa
olfactory nerve
CN I
axons from the mitral cells pass to the telencephalon as the olfactory tract; the olfactory nerve is classified as SVA. (special sense, visceral [smell and taste are associated with the visceral of GI tract], afferent [sensory])
optic nerve
CN II
the optic nerves are formed by the axons of ganglion cells in the retina
SSA fibers (special sense, somatic, afferent)
location of optic chiasm and tracts
diencephalon
oculomotor, trochlear, abducens nerves
motor neves to extraocular muscles
III, IV, VI
CN III, IV, and VI
motor nerves to muscles of the orbit that are derived from head somites (GSE); they supply the extraocular muscles that move the eye
CN III (oculomoter) and cranial nerve IV (trochlear)
arise from the midbrain (mesencephalon)
the oculomotoer nervve CN III
innervates most of the extraocular muscles (GSE); provides parasympathetic preganglionic fibers (GVE) to the ciliary ganglion whose postganglionic fibers help control pupillary diameter
trochlear nerve (CN IV)
supplies one eye muscle, the superior oblique; it is the only cranial nerve to original from the dorsal or superior surface of the midbrain
abducens (or abducent nerve) (CN VI)
supplies one eye muscle, the lateral rectus; it is actually a nerve of the myelencephalon and arise from the brain at the pons-medulla junction; it travels into the orbit with the cranial nerves III, IV, and V1
trochlear nerve
left outside of the tendinous ring; its muscle (superior onliue) also doesn’t attach to the ring
trigeminal nerve (V)
attached to the middle pons at the level of the cerebellar peduncle; it has motor and sensory roots; most cell bodies contributing to the sensory root are located in the trigeminal ganglion which lies in a pocket of dura mater just lateral to the cavernous sinus; sensory neurons of the trigeminal nerve (V3) innervate structures anterior to the vertex-ear-chin line (GSA). the mandibular division of the trigeminal nerve (V3) also contains motor neurons; these inntervate the muscles of mastication that develop from the first branchial arch (SVE)
exits of trigeminal nerve branches
sup. orbital fissure (CN III, IV, V1, VI)
foramen rotundum (CN V2)
foramen ovale (CN V3)
where do cranial nerves VI, VII, and VIII arise from
from the brain at the pons-medulla junction
the pyramids
a pair of ridges, lie on either side of the anterior median fissure of the medulla; just lateral are bumps called the olives
hypoglossal nerve (XII)
emerges from the groove between the pyramid and olive
glossopharyngeal, vagus, and accessory nerves (IX, X, and XI)
emerge posterior to the olives in the postolivary fissure
facial nerve motor components
the facial nerve innervates muscles of facial epression plus stapedius, stylohyoid, and psoterior digastrist; these are striated muscles derived from the 2nd branchial arch, so teh nerve modality is SVE
facial nerve sensory component
sense of taste from anterior 2/3 of tongue, so SVA; cell bodies for taste fibers are in the geniculate ganglion
facial nerve parasympathetic components
parasympathetic preganglionic fibers (GVE) are in the greater petrosal nerve and the chorda tympani
vestibulocochlear nerve VIII
vestibulo (vestibule - balance); cochlear (cochlea - hearing); Special Somatic Afferent (SSA)
vestibulocochlear nerve
special (special sense) somatic (hearing and balance) afferent (sensory), therefore SSA; inputs to dorsal and ventral cochlear nuclei (hearing); inputs to vestibular nuclei (balance, control of extraocular muscles)
glossopharyngeal n (CN IX)
general sense from middle ear (GSA), general sense from pharynx and psoterior tongue (GVA), taste from posterior tongue (SVA), motor to stylopharyngeus (SVE), parasympathetic supply to parotid gland (GVE)
vagus nerve (CN X)
GVA from GI tract, lungs, heart
GVE parasympathetic preganglionic to GI tract
SVE to 4th arch: pharynx, larynx muscles
accessory nerve (CN XI)
SVE or GSE to striated muscle, depending on text
hypoglossal nerve (CN XII)
the hypoglossal nerve innervates all muscles whose name ends in “glossus,” except palatoglossus; GSE to striated muscles from somites
GVE
parasympathetic preganglionic fibers in cranial nerves III, VII, and IX go to ganglia in the head, controlling lens and pupil of eye, and secretion from mucus and salivary glands
cranial nerves
locations of nuclear columns derived from primitive neural tube
somatic and visceral sensory
are dorsal (posterior)
somatic and visceral motor
are anterior
cranial nerve nuclei
sometimes contribute to more than one cranial nerve; are in order anterior to posterior
GSE (somatic motor)
oculomoter (III), trochlear (IV), abducens (VI), spinal accessory (XI), hypoglossal (XII)
SVE (branchial motor)
trigeminal motor (V), facial motor (VII), ambiguus (IX, X)
GVE (visceral motor - parasympathetic preganglionic)
edinger-wesphal (III), superior salivatory (VII), inferior salivatory (IX), dorsal motor vagal (X)
SSA (special sensory)
vestibular (VIII), cochlear (VIII)
GSA (somatic sensory)
mesencephalic, main, spinal trigeminal (V)
GVA (visceral sensory)
solitarius (IX, X)
SVA (taste)
solitarius (VII, IX, X)
