Cranial Nerves Lecture 3 Flashcards
Olfactory (CN I)
- Function: (SVA) special sense of smell
- Location: Olfactory organ
- Tract: Cribriform plate to olfactory bulbs
Anosmia
Olfactory loss • Contralateral nostril can compensate for unilateral anosmia • Causes: Head trauma, viral infections, Intracranila lesions, nasal passage obstruction
Optic (CN II) function
(SSA) special sense of
vision
Optic (CN II) tract
• Optic nerve fibers arise from ganglion cells in retina • Exit the orbit via the optic canal into the middle cranial fossa • Most fibers terminate in lateral geniculate bodies of thalamus
what is relationship of optic chiasm to pituitary?
right next to each other. Pituitary can compress and cause lateral vision loss in both fields (bitemporal hemainopia)
what is relationship of internal carotid artery to optic chiasm
next to each other. aneurysm can compress optic chiasm
CN II testing
- light and dark (head injury
- finger counting (head injury)
- snellens test (eye chart)
- visual field test (4 quadrants)
- peripheral vision
- pupillary light reflex
- blink reflex
Oculomotor (CN III) function
• (GSE) Motor innervation to superior, medial, and inferior recti and inferior oblique and levator palpebrae superioris • (GVE) Parasympathetic innervation to pupil and ciliary muscle
Oculomotor (CN III) tract
• Leaves the midbrain • Pierces dura lateral to diaphragma sellae • Runs in lateral wall of cavernous sinus • Enters orbit via superior orbital fissure
Trochlear (CN IV) function
Motor innervation to
superior oblique
Trochlear (CN IV) tract
• Exits dorsal surface of midbrain • Pierces dura mater at the margin of the tentorium cerebelli • Run in the lateral wall of cavernous sinus • Enters the orbit via the superior orbital fissure
Abducens (CN VI) function
• (GSE) Motor innervation to the
lateral rectus
Abducens (CN VI) tract
• Emerges from brainstem between pons and medulla • Traverses the pontine cistern • Pierces dura covering the clivus • Runs in the cavernous sinus near the ICA • Enters orbit via superior orbital fissure
which 2 nerves can be compressed by aneurysm?
CN III and CN VI (between 2 arteries)
Trigeminal (CN V) function
• (SVE) Motor innervation to muscles
of mastication (pharyngeal arch 1)
• (GSA) Sensory to the face and
scalp
Trigeminal (CN V) tract
• Emerges from lateral aspect of pons
• Trigeminal ganglion located in the
trigeminal cave lateral to the
cavernous sinus
*branches to 3 different divisions
• V1 Ophthalmic: tract
Passes through the
cavernous sinus and enters the orbit
via the superior orbital fissure
v2 maxillary tract
Passes through the
cavernous sinus and exits the skull
via foramen rotundum
v3 mandibular tract
Exits the skull via the
foramen ovale
• Ophthalmic division: CN V
Sensation from cornea, skin of forehead and
scalp, upper eye lid, part of nose and part of
nasal cavity
Maxillary division: CN V
Sensation from skin of face, lower eyelid,
cheek, upper lip, maxillary teeth, mucosa of
nose, maxillary sinus
Mandibular division: CN V
Sensation from skin of mandible, lower lip
side of head, mandibular teeth, TMJ joint,
part of oral mucosa, anterior 2/3 of tongue
• Motor to muscle of mastication
Facial (CN VII)
• Function:• (SVE)
• (SVE) Motor innervation to muscles of facial expression (pharyngeal arch 2)
Facial (CN VII)
• Function:• (GVE)
• (GVE) Parasympathetic innervation to lacrimal, nasal, and palatine glands,
and submandibular and sublingual salivary glands
Facial (CN VII)
• Function:•• (SVA)
• (SVA) Taste to anterior 2/3 of tongue
Facial (CN VII)
• Function:•• (GSA)
• (GSA) Sensation to eternal acoustic meatus
Facial Nerve tract
Tract:
• Emerges from pontine-medullary junction
• Traverses the posterior cranial fossa and exits the skull via the internal
acoustic meatus
• Runs in the facial canal and exits via the stylomastoid foramen
• Passes through the parotid gland
bells palsy
- problem with CN VII (facial)
- test= close eye and smile
Vestibulocochlear (CN VIII) function
• (SSA) Special sense of hearing and equilibrium
Vestibulocochlear (CN VIII) tract
• Vestibular nerve innervates the utricle and saccule, cochlear nerve innervates
the cochlea.
• Enter skull via the internal acoustic meatus
• Enter brainstem on the pontine-medullary junction
Glossopharyngeal (CN IX) function GSA
Sensation from ear and external auditory canal, and posterior 1/3 of tongue
Glossopharyngeal (CN IX) tract
• Emerges from medulla • Exits cranium through jugular foramen • Passes between the superior and middle pharyngeal constrictors • Enters oral cavity
Glossopharyngeal (CN IX) function GVA
Sensory information from oropharynx and carotid body
Glossopharyngeal (CN IX) function SVA
(SVA) Taste to the posterior 1/3 of tongue
Glossopharyngeal (CN IX) function GVE
Parasympathetics to parotid gland
Glossopharyngeal (CN IX) function SVE
(SVE) Motor to stylopharyngeus muscles (pharyngeal arch 3)
what 2 nerves are tested at same time?
glossopharyngeal and vagus (gag reflex)
Glossopharyngeal Neuralgia
- eating and swallowing starts an intense pain
- idiopathic
Vagus (CN X) GSA
Sensation from external auditory canal and dura
Vagus (CN X) GVA
Sensory information from viscera, pharynx, larynx,
aortic arch, epiglottis, and base of tongue
Vagus (CN X) SVA
Taste from epiglottis
Vagus (CN X) GVE
Parasympathetics to viscera
Vagus (CN X) SVE
Motor to constrictors of pharynx, palatine muscles, and
intrinsic muscle of larynx (pharyngeal arch 4 & 6)
Vagus (CN X) tract
- Emerges from medulla
* Exits cranium through jugular foramen
Spinal Accessory (CN XI) function
• (GSE) Motor to sternocleidomastoid and trapezius
*no sensory
Spinal Accessory (CN XI) tract
• Tract: • Emerges from the spinal cord • Enters the cranium through foramen magnum • Exits the skull through the jugular foramen
Hypoglossal (CN XII) GSE
Motor to intrinsic tongue muscles, and styloglossus,
hypoglossus and genioglossus.
Hypoglossal (CN XII) tract
- Tract:
- Emerges from the medulla
- Exits skull via hypoglossal canal
- Travels with the cervical plexus
- Crosses the occipital artery
- Enters the oral cavity
