Cranial nerves

1. Ivano-Frankivsk National Medical University
The Department of Human anatomy
The Cranial Nerves
Prepared by PhDPrepared by PhD
Tetyana Knyazevych - ChornaTetyana Knyazevych - Chorna

2.  Cranial nerves are nerves
that emerge directly from
the brain, in contrast to spinal
nerves, which emerge from
segments of the spinal cord.
In humans, there are
traditionally twelve pairs of
cranial nerves. Only the first
and the second pair emerge
from the cerebrum; the
remaining ten pairs emerge
from the brainstem.

3. Names of cranial nerves
 Ⅰ Olfactory nerve
 Ⅱ Optic nerve
 Ⅲ Oculomotor nerve
 Ⅳ Trochlear nerve
 Ⅴ Trigeminal nerve
 Ⅵ Abducent nerve
 Ⅶ Facial nerve
 Ⅷ Vestibulocochlear nerve
 Ⅸ Glossopharyngeal nerve
 Ⅹ Vagus nerve
 Ⅺ Accessory nerve
 Ⅻ Hypoglossal nerve

4. Classification of cranial nerves
 Sensory cranial nerves: contain only afferent (sensory)
fibers
 ⅠOlfactory nerve
 ⅡOptic nerve
 Ⅷ Vestibulocochlear nerve
 Motor cranial nerves: contain only efferent (motor) fibers
 Ⅲ Oculomotor nerve
 Ⅳ Trochlear nerve
 ⅥAbducent nerve
 Ⅺ Accessory nerv
 Ⅻ Hypoglossal nerve
 Mixed nerves: contain both sensory and motor fibers---
 ⅤTrigeminal nerve,
 Ⅶ Facial nerve,
 ⅨGlossopharyngeal nerve
 ⅩVagus nerve

5. Cranial Nerve I: Olfactory
 Arises from the
olfactory epithelium
 Passes through the
cribriform plate of the
ethmoid bone
 Fibers run through the
olfactory bulb and
terminate in the
primary olfactory
cortex (uncus)
 Functions solely by
carrying afferent
impulses for the sense
of smell
 Lesions result in
ANOSMIA

6. Cranial Nerve II: Optic
 Arises from the retina of the
eye
 Optic nerves pass through the
optic canals and converge at
the optic chiasm
 They continue to the thalamus
where they synapse
 From there, the optic radiation
fibers run to the visual cortex
 Functions solely by carrying
afferent impulses for vision

7. Cranial Nerve III: Oculomotor
 Fibers extend from the ventral midbrain, pass
through the superior orbital fissure, and go to the
extrinsic eye muscles
 Functions in raising the eyelid, directing the
eyeball, constricting the iris, and controlling lens
shape
 The latter 2 functions are parasympathetically
controlled
 Parasympathetic cell bodies are in the ciliary
ganglia

8. Cranial Nerve III: Oculomotor
Figure III from Table 13.2

9. Cranial Nerve IV: Trochlear
 Fibers emerge from the dorsal midbrain and
enter the orbits via the superior orbital fissures;
innervate the superior oblique muscle
 Primarily a motor nerve that directs the eyeball

10. Cranial Nerve V: Trigeminal
 Composed of three divisions
 Ophthalmic (V1)
 Maxillary (V2)
 Mandibular (V3)
 Fibers run from the face
to the pons via the
superior orbital fissure
(V1), the foramen
rotundum (V2), and the
foramen ovale (V3)

11.  Ophthalmic nerve
 Sensory from the eyes,
conjunctiva and orbital
contents including the
lacrimal gland
 Maxillary nerve
 Sensory branches from
anterior and middle cranial
fossa, nasopharynx, palate,
nasal cavity, teeth of the
upper jaw, maxillary sinus,
skin of the side of the nose,
lower eyelid, cheek, upper
lip
 Mandibular nerve
 Motor fibers innervate
muscles of mastication,
tensor veli palatini,
mylohyoid, anterior
belly of digastric,
tensor tympani
 Sensory fibres from the skin
of the lower face, cheek,
lower lip, ear, external
auditory meatus and
temporal region, anterior
two thirds of the tongue,
teeth of the lower jaw,
mastoid air cells, mucous
membrane and dura in the
middle cranial fossa

13.  Lesion involves loss of
sensation, weakness in
chewing, Jaw deviation towards
the affected side
 (Tic douloureux) or trigeminal
neuralgia
 - Most excruciating pain
known
 - Caused by inflammation of
nerve
 - In severe cases, nerve is
cut; relieves agony but results
in loss of sensation on that side
of the face

14. Cranial Nerve VI: Abducens
 Fibers leave the inferior pons and enter the orbit
via the superior orbital fissure
 Primarily a motor nerve innervating the lateral
rectus muscle (abducts the eye; thus the name
abducens)

15. Cranial Nerve VII: Facial
 Fibers leave the pons, travel through the internal
acoustic meatus, and emerge through the
stylomastoid foramen to the lateral aspect of the face
 Motor functions include;
 Facial expression
 Transmittal of parasympathetic impulses to
lacrimal and salivary glands (submandibular and
sublingual glands)
 Sensory function is taste from taste buds of anterior
two-thirds of the tongue

16. Cranial Nerve VII: Facial
Figure VII from Table 13.2

18. Facial Nerve (CN VII)
 Bell’s palsy: paralysis of facial
muscles on affected side and loss
of taste sensation
 Caused by herpes simplex I virus
 Lower eyelid droops
 Corner of mouth sags
 Tears drip continuously and eye
cannot be completely closed (dry
eye may occur)
 Condition may disappear
spontaneously without treatment

19. Cranial Nerve VIII:
Vestibulocochlear
 Fibers arise from the hearing and equilibrium
apparatus of the inner ear, pass through the
internal acoustic meatus, and enter the
brainstem at the pons-medulla border
 Two divisions – cochlear (hearing) and
vestibular (balance)
 Functions are solely sensory – equilibrium and
hearing

20. Cranial Nerve VIII: Vestibulocochlear
Figure VIII from Table 13.2

21. Cranial Nerve IX:
Glossopharyngeal
 It receives general sensory fibers from the tonsils,
the pharynx, the middle ear and the posterior 1/3 of
the tongue.
 It receives special sensory fibers (taste) from the
posterior one-third of the tongue.
 It receives visceral sensory fibers from the carotid
bodies, carotid sinus.
 It supplies parasympathetic fibers to the parotid
gland via the otic ganglion.
 It supplies motor fibers to stylopharyngeus muscle,
the only motor component of this cranial nerve.
 It contributes to the pharyngeal plexus.

22. Cranial Nerve IX: Glossopharyngeal
Figure IX from Table 13.2

23. Cranial Nerve X: Vagus
(pneumogastric nerve )
 The Dorsal nucleus of vagus nerve -
which sends parasympathetic output to
the viscera (esp. intestines)
 The Nucleus ambiguus - which sends
parasympathetic output to the heart
(slowing it down)
 The Solitary nucleus - which receives
afferent taste information and primary
afferents from visceral organs

24.  Auricular nerve
 Pharyngeal nerve
 Superior laryngeal nerve
 Superior cervical cardiac branches
 Inferior cervical cardiac branch
 Recurrent laryngeal nerve
 Thoracic cardiac branches
 Branches to the pulmonary plexus
 Branches to the esophageal plexus
 Anterior vagal trunk
 Posterior vagal trunk

25. Cranial Nerve X: Vagus

26. Cranial Nerve XI: Accessory
 Formed from a cranial root emerging from the
medulla and a spinal root arising from the
superior region of the spinal cord
 The spinal root passes upward into the
cranium via the foramen magnum
 The accessory nerve leaves the cranium via
the jugular foramen
 Innervates the trapezius and sternocleidomastoid,
which move the head and neck

27. Cranial Nerve XI: Accessory
Figure XI from Table 13.2

28. Cranial Nerve XII: Hypoglossal
 Fibers arise from the medulla and exit the
skull via the hypoglossal canal
 Innervates both extrinsic and intrinsic
muscles of the tongue, which contribute to
swallowing and speech
 If damaged, difficulties in speech and swallowing

29. Cranial Nerve XII: Hypoglossal
Figure XII from Table 13.2

32. The ciliary ganglion
 The ciliary ganglion is a parasympathetic ganglion
located in the posterior orbit. Preganglionic axons
from the Edinger-Westphal nucleus travel along the
oculomotor nerve and form synapses in ganglion.
The postganglionic axons run in the short ciliary
nerves and innervate two eye muscles:
 the sphincter pupillae constricts the pupil, a
movement known as Miosis. The opposite - dillatator
pupillae ,Mydriasis, is the dilation of the pupil.
 the ciliaris muscle contracts, releasing tension on
the Zonular Fibers, making the lens more convex,
also known as accommodation.
 Both of these muscles are involuntary – they are
controlled by the autonomic nervous system.

33.  The fibers that simply
pass through
ganglion:
 a sympathetic root of
ciliary ganglion
 a sensory root of
ciliary ganglion

34.  The pterygopalatine
ganglion (Synonym: meckel's ganglion)
is a parasympathetic ganglion found in
the pterygopalatine fossa.
 The pterygopalatine ganglion supplies the
lacrimal gland, paranasal sinuses, glands
of the mucosa of the nasal cavity and
pharynx, the gingiva, and the mucous
membrane and glands of the hard palate.
It communicates anteriorly with the
nasopalatine nerve.

35.  Its sensory root is derived from two sphenopalatine branches of
the maxillary nerve
 Its parasympathetic root is derived from the nervus intermedius
(a part of the facial nerve) through the greater petrosal nerve.
 The ganglion also consists of sympathetic efferent
(postganglionic) fibers from the carotid plexus - the deep
petrosal nerve. The deep petrosal nerve joins with the greater
petrosal nerve to form the nerve of the pterygoid canal (Vidian),
which enters the ganglion.

36.  The otic ganglion is a small, oval shaped,
flattened parasympathetic ganglion of a reddish-gray
color, located immediately below the foramen ovale
in the infratemporal fossa. It gives innervation to
the parotid gland for salivation.

37.  The sympathetic postganglionic fibers consists of a
filament from the plexus surrounding the middle
meningeal artery.
 Its sensory root is derived from the maxillary nerve
 Preganglionic parasympathetic fibers originate from
the glossopharyngeal nerve via the lesser petrosal
nerve.
 Postganglionic parasympathetic fibers travel with the
sympathetic fibers of the auriculotemporal nerve to
supply the parotid gland.

38.  The submandibular ganglion is responsible for
innervation of two salivary glands: the
submandibular gland and sublingual gland.
 It is situated above the deep portion of the
submandibular gland, on the hyoglossus muscle,
near the posterior border of the mylohyoid muscle.

39.  Sympathetic fibers from the
external carotid plexus, via the
facial nerve and its branches.
 Its sensory root is derived from
the mandibular nerve
 Preganglionic parasympathetic
fibers via the chorda tympani
and lingual nerve, which
synapse at the origin of:
 Postganglionic
parasympathetic fibers to the
oral mucosa and the
submandibular and sublingual
salivary glands.They are
secretomotor to these glands.