NERVE
CN 0: TERMINAL
FIBER
SVA
INNERVATION
Nasal septum
FUNCTIONS and DEFICITS
Involved in specialized olfaction of reproduction
(pheromones); exhibits GnRH; damage leads to mating deficits
“OUT”
Cribiform
foramen
“IN”
Cribiform
foramen
Cribiform
foramen
Cribiform
foramen
Optic
foramen
Optic canal
CN I: OLFACTORY
SVA
Olfactory epithelium of caudal
nasal mucosa
Deficits result in anosmia (absence of smell), hyposmia
(reduced olfactory sense)
CN II: OPTIC
SSA
Light-sensitive part of retina
Involved in visual processing, pupillary reflexes, and
regulating body rhythm
CN III: OCULOMOTOR
GSE
GVE
Muscles of the eye
Pupillary constrictor mm.
Motor branches
GSE
Dorsal rectus m.
Ventral rectus m.
Medial rectus m.
Ventral oblique m.
Levator palpebrae superioris m.
Deficits results in ptosis (droopy eyelid) and ventrolateral
strabismus
Short ciliary nn.
GVE
Pupillary constrictory mm.
cilliary mm. (lens)
CN IV: TROCHLEAR
GSE
Dorsal oblique m.
CN V: TRIGEMINAL
Ophthalmic n. (V1)
GSA
SVE
GSA
Fibers synapse at ciliary ganglion, which sends postganglionic
parasympathetic fibers to muscles. Deficits lead to mydriasis
(dilated pupil)
Only cranial nerve to originate from the dorsal brain stem and
decussate before leaving cranial cavity (within rostral
medullary vellum). Deficits results in dorsolateral strabismus
Damage results in general sensory deficits, particulary a lack of
the palpebral (blink) reflex
Lacrimal n.
GSA
Lacrimal gland and skin of the
upper eyelid
Also carries postganglionic parasympathetic fibers from the
pterygopalatine ganglion (CN VII) to lacrimal gland
Frontal n.
GSA
Skin of upper eyelid and frontal
area (dorsal to dorsal rectus m.)
Terminates as supraorbital and supratrochlear nn.
Nasociliary n.
GSA
Deep eye structures, skin of upper
eyelid/nose, nasal mucosa
Also carries postganglionic sympathetic fibers from the cranial
cervical ganglion that innervate the smooth muscle of eye
Long ciliary n.
GSA
Eyeball, cornea
Slender fibers seen over CN II
Infratrochlear n.
GSA
Skin on medial upper eyelid and
bridge of nose
Courses ventral to the trochlea near the gland of the third
eyelid
Ethmoid n.
GSA
Mucosa of nasal septum, nasal
cavity, skin of nostril vestibule
*Only nerve to exit (via orbital fissure) and re-enter (via
ventral ethmoid foramen) cranial cavity. Enters nasal cavity
and terminates as the external nasal nn.
Orbital
fissure
Structures and skin of the eye,
nasal mucosa
Orbital
fissure
Trigeminal
canal
Orbital
fissure
Orbital
fissure
Orbital
fissure*
Ventral
ethmoid
foramen*
Maxillary n. (V2)
GSA
Structures of upper jaw
Zygomatic n.
GSA
Courses with the periorbita to
supply superficial eye structures
Zygomaticotemporal n.
GSA
Eyelid, skin over lateral cathus
Dorsal of the two branches
Zygomaticofacial n.
GSA
Ventral of the two branches
Pterygopalatine n.
GSA
Skin over zygomatic arch,
temporalis m., and lateral canthus
Mucosa of nasal cavity and palate
Minor palatine n.
Major palatine n.
GSA
GSA
Mucosa of soft palate
Mucosa of hard palate and ventral
nasal meatus
Accessory palatine n.
GSA
Mucosa of hard palate
Given off by major palatine n. within the palatine canal and
exits via accessory palatine foramen
Caudal nasal n.
GSA
Mucosa of the nasal septum and
ventral nasal meatus, lateral nasal
gland
Infraorbital n.
GSA
Teeth (upper cheek, incisors,
canines), skin of the nose, nasal
mucosa, upper lip
Main continuation that enters the nasal cavity via the
sphenopalatine foramen to supply mucosa. Also carries
postganglionic parasympathetic fibers from the pterygopalatine
ganglion (CN VII) and postganglionic sympathetic fibers from
the cranial cervical ganglion to the lateral nasal gland
Enters the maxillary foramen, traverses the infraorbital canal,
and exits via the infraorbital foramen. Within the canal, gives
off many branches that supply the teeth. Beyond the
infraorbital formamen, gives of external nasal nn. that supply
the skin of the nose, nasal mucosa, and upper lip
Mandibular n. (V3)
GSA
Skin of external ear and ear canal,
cheek, tongue, lower lip and jaw
Muscles of mastication
Because the otic ganglion is located just ventral to the oval
foramen, CN V3 receives many postganglionic parasympathetic
fibers from CN IX. Deficits lead to general sensory defecits,
atrophy of masticatory muscles, and dropped jaw if bilateral
Skin of lateral aspect of cheek,
cheek mucosa
Tympanic membrane, skin of the
external ear canal
Also carries postganglionic parasympathetic GVE fibers (CN
IX) from the otic ganglion to the zygomatic salivary gland
Branches at level of oval foramen. Also carries postganglionic
parasympathetic GVE fibers (CN IX) from the otic ganglion to
the parotid salivary gland
Body (rostral 2/3) of tongue,
intrafusal fibers of intrinsic and
extrinsic tongue muscles
Joins the chorda tympani n. of CN VII that provides taste to the
body of the tongue. Lingual n. branches supply intrafusal fibers
of tongue muscle and have a proprioceptive function
SVE
Buccal n.
GSA
Auriculotemporal n.
GSA
Lingual n.
GSA
Exits the cranial cavity via the round foramen (roof of the alar
canal), courses within the alar canal, then exits via the rostral
alar foramen along with the maxillary a. Damage results in
general sensory deficits
Given off within alar canal
Runs along the lateral surface of the medial pterygoid m.,
ventral to the pterygopalatine ganglion
Runs along rostral margin of medial pterygoid mm
Enters (via caudal palatine foramen) and exits (via major
palatine foramen) the palatine canal. Terminal branches supply
mucosa of ventral nasal meatus with the caudal nasal n.
Rostral alar
foramen*
Round
foramen*
Alar canal
Major
palatine
foramen
Caudal
palatine
foramen
Accessory
palatine
foramen
Sphenopalatine
foramen
Infraorbital
foramen
Oval
foramen
Maxillary
foramen
Inferior alveolar n.
GSA
Lower cheek teeth, canines, and
incisors, lower lip
Mylohioid n.
GSA
SVE
Tensor tympani n.
SVE
Skin of the intermandibular area
Digastricus m. (rostral belly)
Mylohioid m.
Tensor tympani m. within middle
ear cavity
Nerve of the tensor veli
palatini m.
Lateral and medial
pterygoid nn.
Masseteric n.
SVE
Tensor veli palatini m.
SVE
Lateral pterygoid m.
Medial pterygoid m.
Temporalis m.
Masseter m.
Lateral rectus m.
Retractor bulbi mm.
SVE
CN VI: ABDUCENT
GSE
CN VII: FACIAL
GVE
SVE
GSA
SVA
Lacrimal, nasal, and salivary
glands
Muscles of facial expression
External ear and ear canal
Taste from body of tongue
Major petrosal n.
GVE
Lacrimal and lateral nasal glands
Chorda tympani n.
GVE
Mandibular and sublingual
salivary glands
Taste buds of the fungiform
papillae on the body of the tongue
SVA
Stapedial n.
SVE
Stapedius m.
Enters mandibular foramen and passes through mandibular
canal, giving off branches to the lower teeth. Exits the canal via
mental foramina as the mental nn., which supply the lower lip
Usually arises from caudal margin of inferior alveolar n.
Mental
foramina
Mandibular
foramen
Nerve plays an important role in the tympanic reflex, which
prevents vibratory damage to delicate inner ear structures
Involved in opening of the auditory tube
Branches into deep temporal nn. that supply the temporalis m.
and the masseteric n. that supplies the masseter m.
Deficits result in medial strabismus (due to impaired lateral
rectus m.), lack of corneal reflex with keratitis sicca (impaired
retractor bulbi mm. leads to inability to retract globe and
protrude third eyelid)
Mainly a motor (GVE, SVE) nerve with a small sensory (GSA,
SVA) component. *The combined nerve exits the cranial
cavity via the dorsal foramen of the internal ear canal, which
leads to the facial canal. CN VII gives off three branches
within the canal, exits the facial canal via the stylomastoid
foramen and then gives of six more branches
Arises in the facial canal at the location of the geniculate
ganglion. Carries mostly preganglionic parasympathetic fibers
that travel within the petrosal canal and join the deep petrosal
n. (postganglionic sympathetic fibers from the cranial cervical
ganglion) to form the nerve of the pterygoid canal. This
nerve exits the cranial cavity. Parasympathetic fibers that first
synapse at the pterygopalatine ganglion and sympathetic fibers
are distributed by branches of CN V2 to the lacrimal and lateral
nasal glands
Preganglionic parasympathetic fibers of the chorda tympani n.
synapse at the mandibular and sublingual ganglia and course
to the mandibular and sublingual salivary glands. After exiting
the cranial cavity, the nerve joins with the lingual n. of CN V 3
to be distributed to taste buds of the fungiform papillae over
the body of the tongue. Deficits can lead to reduced salivation
and atrophy of fungiform papillae.
Arises in the facial canal; responsible for tympanic reflex
Orbital
fissure
Stylomastoid
foramen
Pterygoid
canal
Facial
canal*
Caudal auricular n.
SVE
Platysma m., caudal muscles of
external ear
Damage results in a droopy lip and ear due to loss of tone of
the muscles of the face and ear
Digastric n.
SVE
Caudal belly of digastricus m.
Jugulohyoidius m.
Stylohioideus m.
Small branch supplying a masticatory muscle and minor
muscles of the hyoid apparatus
Buccal nn.
SVE
Zygomaticus m
Buccinator m.
Auriculopalpebral n.
SVE
Rostral muscles of external ear
Orbicularis oculi m.
Retractor anguli lateralis m.
Levator nasolabialis m.
Dorsal and ventral buccal nn. course over the lateral surface
of the masseter m. to supply the two muscles. Nerve deficits
result in paralysis of the only muscle of the cheek, leading to
the accumulation of food boli and subsequent infection. The
dorsal buccal n. receives communicating branches from the
auriculotemporal n. of CN V3.
Divides into a rostral auricular n. that supplies the rostral
muscles of the external ear and palpebral n. that supplies
muscles of the eye and nose. Damage to the palpebral n. results
in loss of the blink reflex and keratitis sicca (due to eye
remaining open)
Internal auricular nn.
GSA
Skin of the external ear and
external ear canal
Cervical n.
GSA
Platysma m.
Parotidauricularis m.
Sphincter coli profundus m.
Cochlea
Vestibular apparatus
VIII: VESTIBULOCOCHLEAR
IX: GLOSSOPHARYNGEAL
Lingual n.
Carotid n.
SSA
GVA
SVA
SVE
GVE
GVA
SVA
GVA
Root of tongue, carotid sinus
Taste buds on root of tongue
Stylopharyngeus m.
Parotid/zygomatic salivary glands
Root of tongue
Taste buds of foliate and vallate
papillae on the root of the tongue
Carotid sinus chemoreceptros and
baroreceptors
Three sets of auricular nn. are given off by CN VII. The
middle and caudal auricular nn. provide sensory innervation
to the external ear. The lateral internal auricular n. provides
sensory innervation to the skin of the external ear canal. This
nerve also carries branches of CN X. Thus, irritation on the
external ear canal can provoke an emetic reflex (vomiting).
Damage to the auricular nn. results in lack of sensory
innervation to the surface of the external ear
Sometimes given off as a branch of the ventral buccal n. of CN
VII. Runs over lateral surface of mandibular salivary gland, so
must be careful during surgical procedures of the gland
Cochlear n. is involved in hearing while the vestibular n. is
involved in balance. Cochlear n. deficits result in hearing
impairment or deafness. Unilateral deficits to the vestibular n.
results in head tilt, circling, rolling, positional strabismus, and
spontaneous or position nystagmus. Bilateral deficits results in
exagerrated head movement
CN IX is a mixed nerve primarily involved with the tongue and
pharynx. Together with CN X, it controls the swallowing reflex
Provides both general sensation and gustatory innervation to
the root of the tongue. Damage results in loss of general
sensation to the tongue and atrophy of papillae
Innervates receptors of the carotid sinus that respond to
changes in blood pressure and pH (called “buffer nerves”)
Internal
acoustic
meatus
Jugular
foramen
Phayrngeal n.
SVE
GVA
(maybe)
Tympanic n.
GVE
Parotid and zygomatic salivary
glands
GVA
GSA
SVA
GVE
Laryngeal mucosa, esophagus
Skin of the external ear
Taste buds of the epiglottis
Smooth muscle and glands of the
larynx, trachea, and esophagus
Most pharyngeal and laryngeal
mm.
Skin of external ear canal
X: VAGUS
SVE
Internal auricular n.
GSA
Pharyngeal n.
SVE
GVA
GVE
Stylopharyngeous m.
Pharyngeal mucosa
Joins the pharyngeal n. of CN X and the postganglionic
sympathetic fibers from the cranial cervical ganglion to form
the pharyngeal plexus. Fibers from CN IX innvervate the
stylopharyngeus m., the only dilator of the pharynx and may
also provide sensory innervation (GVA) to the pharynx.
Damage results in dysphagia (difficulty swallowing)
Becomes the minor petrosal n., which is mostly composed of
preganglionic parasympathetic fibers that synapse at the otic
ganglion. These fibers are distributed to the parotid salivary
gland via the auriculotemporal n. of CN V3 or the zygomatic
salivary gland via the buccal n. of CN V3
Most of CN X (80%) is composed of sensory GVA fibers
while a minor proportion (20%) consists of GSA, SVA, SVE,
and GVE fibers
Joins CN VII to become the lateral auricular n. Irritation of the
external ear canal may trigger reflex vomition
All pharyngeal muscles except
stylopharyngeous m.
Cervical esophagus
Cervical esophagus
Joins pharyngeal n. of CN IX to supply the pharyngeal mm.
Branch supplies both sensory and motor fibers to the cervical
esophagus. Bilateral CN X deficits may result in
megaesophagus
Cricoarytendoideus dorsalis m.
Laryngeal mucosa
Taste buds of the epiglottis
Smooth muscle and glands of the
larynx, trachea, and esophagus
Laryngeal mucosa
Cricothyroideus m.
SVE fibers are distributed the cricoarytendoideus dorsalis m.
(only dilator of the larynx) via the recurrent laryngeal n. of CN
X, though the fibers are mainly derived from CN XI. Damage
results in larygneal paralysis and difficulty breathing.
Recurrent laryngeal n.
SVE
GVA
SVA
GSE
Cranial laryngeal n.
GVA
SVE
Caudal laryngeal n.
SVE
All laryngeal mm. except
cricothyroideus m.
XI: ACCESSORY
SVE
GSA
Cricoarytenoideus dorsalis m.
Intrafusal muscle fibers
XII: HYPOGLOSSAL
GSE
Intrinsic and extrinsic muscles of
the tongue
Jugular
foramen
Given off at the nodose ganglion. Internal branch is larger
and sensory to the laryngeal mucosa. External branch
supplies cricothyroideus m. Damage may result in dysphagia.
Main continuation of the recurrent laryngeal n. Damage may
result in laryngeal paralysis.
Most SVE fibers from CN XI are distributed to muscles of the
esophagus and larynx via the recurrent laryngeal n. of CN X.
GSA fibers provide proprioception
Muscle innervation may also be provided by C1 due to its
connection to CN XII via the ansa cervicalis. Damage results
in paralysis and atrophy of the tongue muscles
Jugular
foramen
Hypoglossal
canal