Download The Cranial Nerves [9-29

The Cranial Nerves
The 12 pairs of cranial nerves are parts of the PNS and pass through foramina or fissures in the cranial
cavity. All but one, the Accessory Nerve [XI], originate from the brain.
Each developing pharyngeal arch of an embryo is associated with a developing cranial nerve:
1)
2)
3)
4)
5)
First arch: Trigeminal Nerve [V3]
Second arch: Facial Nerve [VII]
Third arch: Glossopharyngeal Nerve [IX]
Fourth arch: superior laryngeal branch of the Vagus Nerve [X]
Sixth arch: recurrent laryngeal branch of the Vagus Nerve [X]
Names and Locations:
#
I
Nerve
Olfactory
II
III
IV
V
Optic
Oculomotor
Trochlear
Trigeminal
VI
VII
VIII
Abducent
Facial
Vestibulocochle
ar
Glossopharynge
al
Vagus
Accessory
Hypoglossal
IX
X
XI
XII
Exit from Skull
Cribiform plate of
ethmoid
Optic canal
Superior orbital fissure
Superior orbital fissure
Superior orbital fissure
[V1], foramen rotundum
[V2], foramen ovale [V3]
Superior orbital fissure
Stylomastoid foramen
Internal acoustic meatus
Jugular foramen
Jugular foramen
Jugular foramen
Hypoglossal canal
Functional Components: Types of fibers and Parasympathetic components
I.
II.
III.
IV.
V.
VI.
VII.
VIII.
Olfactory: SA
Optic: SA
Oculomotor: GSE, GVE
Trochlear: GSE
Trigeminal: GSA, BE
Abducent: GSE
Facial: GSA, SA, GVE, BE
Vestibulocochlear: SA
IX.
X.
XI.
XII.
Glossopharyngeal: GVA, GSA, SA,
GVE, BE
Vagus Nerve: GSA, GVA, SA, GVE, BE
Accessory: GSE
Hypoglossal: GSE
Functions: some cranial nerves carry motor or sensory or both.
#
I
Nerve
Olfactory
Function
Smell
II
Optic
Vision
GSE- levator palpebrae superioris, superior and
inferior rectus, medial rectus, inferior oblique
muscles of eye.
III
IV
V
VI
Oculomotor
Trochlear
Trigeminal
Abducent
GVE- (parasympathetic) sphincter papillae for
papillary constriction, ciliary muscles of the lens
for near vision
Superior oblique muscle of eye
GSA- sensory from face, anterior ½ scalp, mucous
membranes of oral and nasal cavities and the
paranasal sinuses, nasopharynx, part of ear and
external auditory meatus, part of tympanic
membrane, orbital contents and conjunctiva, and
the dura mater of the anterior and medial cranial
fossae
BE- muscles of mastication, the tensor tympani,
tensor veli palitini, mylohyoid, and the anterior
belly of the digastric (motor is only from [V3])
Lateral rectus muscle of the eye
Potential Deficits
Loss of smell
Blindness, visual field
abnormalities, loss of
papillary constriction
Dilated pupils, ptosis,
loss of normal papillary
reflex, eye moves down
and out (down
inferiorly and laterally)
Inability to look
inferiorly when eye is
adducted
Loss of sensation in
facial sections supplied
by [V], loss of motor to
mastication muscles
(on same side as lesion)
Inability to move eye
laterally
GSA- sensory from external auditory meatus and
deeper parts of the auricle
SA- taste for the anterior 2/3 of the tongue
VII
VIII
Facial
Vestibulocochlear
GVE- (parasympathetic) stimulate secretomotor
activity of the lacrimal glands, submandibular and
sublingual salivary glands, and the glands in the
mucous membrane of the nasal cavity, and the
hard and soft palates
BE- innervate the muscles of the face and scalp,
stapedius, posterior belly of digastric, and the
stylohyoid muscle
Balance (vestibular division) and hearing (cochlear
division)
Paralysis of facial
muscles, abnormal
taste sensation from
anterior 2/3 of tongue,
Progressive unilateral
hearing loss and ringing
in the ears (tinnitis)
GVA- sensory from carotid body and sinus
GSA- sensory from posterior 1/3 tongue, palatine
tonsils, oropharynx, and mucosa of the middle ear
and eustachain tube
IX
Glossopharyngeal
SA- taste from posterior 1/3 of the tongue
GVE- (parasympathetic) secretomotor activity in
the parotid gland
Loss of taste to
posterior ½ of tongue
and sensation to the
soft palate
BE- stylopharyngeus muscle
GSA- sensory from larynx, laryngopharynx, deeper
parts of auricle, part of external auditory meatus,
dura mater in the posterior cranial fossae
GVA- sensory from aortic body chemoreceptors,
aortic arch baroreceptors, esophagus, bronchi,
lungs, heart, abdominal viscera in foregut and
midgut
X
Vagus
SA- taste around the epiglottis and pharynx
GVE- (parasympathetic) stimulate smooth muscle
and glands in the pharynx, larynx, thoracic viscera,
abdominal viscera of foregut and midgut
Soft palate deviation
with deviation of the
uvula to the normal
side, vocal cord
paralysis
BE- palatoglossus (tongue), muscles of the soft
palate (except tensor veli palatine), pharynx
(except stylopharyngeus), and larynx
XI
Accessory
Sternocleidomastoid and trapezius
XII
Hypoglossal
Hyoglossus, genioglossus, styloglossus muscles, all
intrinsic tongue muscles
Paralysis of
sternocleidomastoid
and trapezius
Atrophy of ipsilateral
muscles of the tongue
and deviation toward
the affected side;
speech disturbance
Parasympathetic Cranial Nerve Ganglia
Ganglion
Ciliary
Input Function
[III]
CN origin
[III]
Pterygopalatine
Greater petrosal nerve
[VII]
Function
Innervation of sphincter
papillae muscle for
papillary constriction
and ciliary muscles for
lens accommodation
Innervate lacrimal
Otic
Submandibular
Lesser petrosal nerve
Chorda tympani to
lingual
[IX]
[VII]
gland, mucous glands of
nasal cavity, maxillary
sinus, and palate
Innervate parotid gland
Innervate
submandibular and
sublingual glands
Cranial Nerve Ganglia
Ganglion
Trigeminal
Geniculate
Superior and Inferior
Superior and Inferior
Cranial Nerve Distribution:
Input
[V1], [V2], [V3]
[VII], greater petrosal nerve
Sensory of [IX]
Sensory of [X]
Cranial Nerve
[V]
[VII]
[IX]
[X]