CRANIAL NERVES - University of Kansas Medical Center
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Transcript CRANIAL NERVES - University of Kansas Medical Center
CRANIAL NERVES
I, II, IV, VI, VIII, XI, XII
Modalities
SSS:
Special Sensory:
Special senses derived from ectoderm:
Sight, sound, balance.
SVS:
Special Visceral Sensory:
Special senses derived from endoderm:
Taste
SVM:
Special Visceral Motor:
Muscles derived from pharyngeal arches.
Modalities
GVS:
General Visceral Sensory:
General sensation from viscera.
GVM:
General Visceral Motor:
To smooth muscles of gut tract.
Autonomic motor
GSS:
General Somatic Sensory:
General senses from ectoderm (skin).
GSM:
General Somatic Motor:
Skeletal muscles.
Generalizations
Cranial nerves have same basic structure
as spinal nerves.
Dorsal root and ventral root.
Dorsal root ganglion.
Motor components of cranial nerves begin
within brain within motor nuclei.
Comparable to spinal cord anterior horns.
Cell bodies of sensory fibers are located in
dorsal root (cranial) ganglia.
Generalizations
Special sensory cranial nerves:
Are actually tracts.
No motor nuclei and no sensory ganglia.
Motor cranial nerves:
Begin in cranial motor nuclei.
Have no sensory roots and no sensory root ganglia.
Mixed cranial nerves:
Have both cranial motor nuclei and sensory ganglia.
Sensory ganglia are usually given specific names.
Generalizations
For each cranial nerve know:
Modality (modalities).
Function (functions).
Sensory areas and/or muscles innervated.
Foramen through which it passes.
Specific ganglion (if applicable).
Specific information included in this slide
presentation.
Olfactory Nerve (CN I)
Olfactory nerve fibers pass from:
Olfactory receptor cells.
Through:
Cribriform plate.
To:
Olfactory bulbs.
Modality:
SVS
Optic Nerve (CN II)
Begins in ganglionic layer of retina (not
rods and cones).
Exits orbit through optic canal.
50% decussation in optic chiasma:
Near pituitary gland.
Near internal carotid.
Modality:
SSS
Oculomotor Nerve (CN III)
Supplies four of the six extrinsic muscles
of the eye.
Has a parasympathetic component.
Will be discussed in a group with other
parasympathetic nerves.
Trochlear Nerve (CN IV)
Enters orbit through superior orbital
fissure.
Innervates superior oblique muscle of the
eye.
Modality:
GSM.
Only crossed cranial nerve.
Only cranial nerve that emerges dorsally.
Abducens Nerve (CN VI)
Enters orbit through superior orbital
fissure.
Lies on medial aspect of lateral rectus
muscle.
Innervates lateral rectus muscle of the
eye.
Modality:
GSM.
Vestibulocochlear Nerve (CN VIII)
Leaves cranial cavity via internal acoustic
meatus:
Accompanied by facial nerve.
Modality:
SSS
Auditory (cochlear) component:
Cell bodies in spiral ganglion of cochlea.
Function: Hearing.
Vestibulocochlear Nerve (CN VIII)
Vestibular component:
Cell bodies in vestibular ganglion.
From receptors for balance and equilibrium.
Function: Balance.
Spinal Accessory Nerve (CN XI)
Arises from C1-3 (4).
Single trunk enters cranial cavity through
foramen magnum.
Temporarily joins cranial root.
Cranial roots leave with vagus nerve.
Spinal Accessory Nerve (CN XI)
Spinal accessory trunk exits cranial cavity
via jugular foramen.
Supplies:
Sternocleidomastoid and trapezius.
Modality:
SVM.
Hypoglossal Nerve (CN XII)
Exits cranial cavity via hypoglossal
foramen.
Descends anteriorly in neck between
internal carotid and internal jugular.
In neck gives rise to superior root of ansa
cervicalis and a nerve to thyrohyoid
muscle.
Supplies extrinsic and intrinsic muscles of
tongue.
Modality:
GSM.