CRANIAL NERVESCRANIAL NERVES

I, II, IV, VI, VIII, XI, XIII, II, IV, VI, VIII, XI, XII

ModalitiesModalities

SSS:SSS: Special Sensory:Special Sensory:Special senses derived from ectoderm:Special senses derived from ectoderm:Sight, sound, balance.Sight, sound, balance.

SVS:SVS: Special Visceral Sensory:Special Visceral Sensory:Special senses derived from endoderm:Special senses derived from endoderm:TasteTaste

SVM:SVM: Special Visceral Motor:Special Visceral Motor:Muscles derived from pharyngeal arches.Muscles derived from pharyngeal arches.

ModalitiesModalities

GVS:GVS: General Visceral Sensory:General Visceral Sensory:General sensation from viscera.General sensation from viscera.

GVM:GVM: General Visceral Motor:General Visceral Motor:To smooth muscles of gut tract.To smooth muscles of gut tract.Autonomic motorAutonomic motor

GSS:GSS: General Somatic Sensory:General Somatic Sensory:General senses from ectoderm (skin).General senses from ectoderm (skin).

GSM:GSM: General Somatic Motor:General Somatic Motor:Skeletal muscles.Skeletal muscles.

GeneralizationsGeneralizations

Cranial nerves have same basic structure Cranial nerves have same basic structure as spinal nerves.as spinal nerves.

Dorsal root and ventral root.Dorsal root and ventral root.

Dorsal root ganglion.Dorsal root ganglion.

Motor components of cranial nerves begin Motor components of cranial nerves begin within brain within motor nuclei.within brain within motor nuclei.

Comparable to spinal cord anterior horns.Comparable to spinal cord anterior horns.

Cell bodies of sensory fibers are located in Cell bodies of sensory fibers are located in dorsal root (cranial) ganglia.dorsal root (cranial) ganglia.

GeneralizationsGeneralizations

Special sensory cranial nerves:Special sensory cranial nerves:Are actually tracts.Are actually tracts.No motor nuclei and no sensory ganglia.No motor nuclei and no sensory ganglia.

Motor cranial nerves:Motor cranial nerves:Begin in cranial motor nuclei.Begin in cranial motor nuclei.Have no sensory roots and no sensory root Have no sensory roots and no sensory root

ganglia.ganglia.Mixed cranial nerves:Mixed cranial nerves:

Have both cranial motor nuclei and sensory Have both cranial motor nuclei and sensory ganglia.ganglia.

Sensory ganglia are usually given specific names.Sensory ganglia are usually given specific names.

GeneralizationsGeneralizations

For each cranial nerve know:For each cranial nerve know:Modality (modalities).Modality (modalities).

Function (functions).Function (functions).

Sensory areas and/or muscles innervated.Sensory areas and/or muscles innervated.

Foramen through which it passes.Foramen through which it passes.

Specific ganglion (if applicable).Specific ganglion (if applicable).

Specific information included in this slide Specific information included in this slide presentation.presentation.

Olfactory Nerve (CN I)Olfactory Nerve (CN I)

Olfactory nerve fibers pass from:Olfactory nerve fibers pass from:Olfactory receptor cells.Olfactory receptor cells.

Through:Through:Cribriform plate.Cribriform plate.

To:To:Olfactory bulbs.Olfactory bulbs.

Modality:Modality:SVSSVS

Optic Nerve (CN II)Optic Nerve (CN II)

Begins in ganglionic layer of retina (not Begins in ganglionic layer of retina (not rods and cones).rods and cones).

Exits orbit through optic canal.Exits orbit through optic canal.50% decussation in optic chiasma:50% decussation in optic chiasma:

Near pituitary gland.Near pituitary gland.

Near internal carotid.Near internal carotid.Modality:Modality:

SSSSSS

Oculomotor Nerve (CN III)Oculomotor Nerve (CN III)

Supplies four of the six extrinsic muscles Supplies four of the six extrinsic muscles of the eye.of the eye.

Has a parasympathetic component.Has a parasympathetic component.Will be discussed in a group with other Will be discussed in a group with other

parasympathetic nerves.parasympathetic nerves.

Trochlear Nerve (CN IV)Trochlear Nerve (CN IV)

Enters orbit through superior orbital Enters orbit through superior orbital fissure.fissure.

Innervates superior oblique muscle of the Innervates superior oblique muscle of the eye.eye.

Modality:Modality:GSM.GSM.

Only crossed cranial nerve.Only crossed cranial nerve.Only cranial nerve that emerges dorsally.Only cranial nerve that emerges dorsally.

Abducens Nerve (CN VI)Abducens Nerve (CN VI)

Enters orbit through superior orbital Enters orbit through superior orbital fissure.fissure.

Lies on medial aspect of lateral rectus Lies on medial aspect of lateral rectus muscle.muscle.

Innervates lateral rectus muscle of the Innervates lateral rectus muscle of the eye.eye.

Modality:Modality:GSM.GSM.

Vestibulocochlear Nerve (CN VIII)Vestibulocochlear Nerve (CN VIII)

Leaves cranial cavity via internal acoustic Leaves cranial cavity via internal acoustic meatus:meatus:

Accompanied by facial nerve.Accompanied by facial nerve.Modality:Modality:

SSSSSSAuditory (cochlear) component:Auditory (cochlear) component:

Cell bodies in spiral ganglion of cochlea.Cell bodies in spiral ganglion of cochlea.

Function: Hearing.Function: Hearing.

Vestibulocochlear Nerve (CN VIII)Vestibulocochlear Nerve (CN VIII)

Vestibular component:Vestibular component:Cell bodies in vestibular ganglion.Cell bodies in vestibular ganglion.

From receptors for balance and From receptors for balance and equilibrium.equilibrium.

Function: Balance.Function: Balance.

Spinal Accessory Nerve (CN XI)Spinal Accessory Nerve (CN XI)

Arises from C1-3 (4).Arises from C1-3 (4).Single trunk enters cranial cavity through Single trunk enters cranial cavity through

foramen magnum.foramen magnum.Temporarily joins cranial root.Temporarily joins cranial root.

Cranial roots leave with vagus nerve.Cranial roots leave with vagus nerve.

Spinal Accessory Nerve (CN XI)Spinal Accessory Nerve (CN XI)

Spinal accessory trunk exits cranial cavity Spinal accessory trunk exits cranial cavity via jugular foramen.via jugular foramen.

Supplies:Supplies:Sternocleidomastoid and trapezius.Sternocleidomastoid and trapezius.

Modality:Modality:SVM.SVM.

Hypoglossal Nerve (CN XII)Hypoglossal Nerve (CN XII)

Exits cranial cavity via hypoglossal foramen.Exits cranial cavity via hypoglossal foramen. Descends anteriorly in neck between Descends anteriorly in neck between

internal carotid and internal jugular.internal carotid and internal jugular. In neck gives rise to superior root of ansa In neck gives rise to superior root of ansa

cervicalis and a nerve to thyrohyoid muscle.cervicalis and a nerve to thyrohyoid muscle. Supplies extrinsic and intrinsic muscles of Supplies extrinsic and intrinsic muscles of

tongue.tongue. Modality:Modality:

GSM.GSM.