2. Cranial Nerves (Keim) Flashcards
Name the cranial nerves in order.
OH OH OH, TO TOUCH AND FEEL A GIRLS VAGINA AH HEAVEN.
- CN I. Olfactory
- CN II. Optic
- CN III: Oculomotor.
- CN IV: Trochlear
- CN V: Trigeminal
- CN VI: Abducens
- CN VII: Facial
- CN VIII: Vestibulocochlear
- CN IX: Glossopharyngeal
- CN X: Vagus
- CN XI: Spinal Acessory N.
- CN XII: Hypoglossal N
Name the general function of each cranial N.
Some say marry money, but my brother says big boobs matter most.
- CN I. Olfactory: sensory
- CN II. Optic: sensory
- CN III: Oculomotor: motor
- CN IV: Trochlear: motor
- CN V: Trigeminal: both
- CN VI: Abducens: motor
- CN VII: Facial: both
- CN VIII: Vestibulocochlear: sensory
- CN IX: Glossopharyngeal: both
- CN X: Vagus: both
- CN XI: Spinal Acessory N: motor
- CN XII: Hypoglossal N: motor
There are several fibers within the cranial nerves:
- GSE
- GVE
- SVE
- GSA
- GVA
- SSA
- SVA
What are each?
Efferent (motor)
- GSE (general somatic efferent): send somatic efferent information to somatic muscles
- GVE (general visceral efferent): autonomics to smooth/cardiac muscle and glands
- SVE (branchial or special visceral efferent) send info to muscles derived from pharyngeal arches.
Afferent
- GSA (general somatic afferent): send sensory information to the skin, joint capsule, tendon or muscle from ectoderm
- GVA (general visceral afferent) send sensory information. to visceral structures from endoderm
- SSA (sensory somatic afferent): resp for hearing (CN 8), balance (CN 8) and sight (CN2)
- SVA (special visceral afferent): taste (CN 7, 9, 10) and smell (CN 1)
What is the function, location, and tract of the olfactory nerve (CN I)?
- Function: SVA –smell.
- Location: olfactory organ.
- Tract: cribiform plate (in nasal cavity) to olfactory bulbs (in brain)
Head impact can shear olfactory. N. What can happen?
Pt can become anosmic (complete olfactory loss)
How does our sense of smell change with age?
Gradually decreases with age.
Pts will commonly complain for loss of taste
What is ansomia?
What happens if we have unilateral anosmia?
Causes?
- Anosmia. -> complete olfactory loss.
- Our other nostril can compensate for unilateral anosmia.
- Causes:
- head trauma,
- viral infection
- intracranila lesion
- obstruction of nasal passage
What is CSF rhinorrhea with fracture of cribriform plate?
Tested using?
- Can cause CSF leakage through nose.
- Tested via halo sign: clear drainage that forms ring around blood suggests that it is CSF. Thus, we have damage to meninges
Optic nerve (CN II) function
SSA: vision
What is the pathway for the fibers of the optic nerve into the brain?
ganglion cells in the retina -> leaves bony orbit via optic canal of the sphenoid bone -> enters cranial cavity runnning along middle cranial fossa -> optic chiasm -> optic tract -> fibers terminate LGN of the thalamus ->
- Axons are then sent to the optic radiations -> primary visual cortex.
CN II: clinical correactions
What can compress the optic chiasm?
- Optic chiasm is located near pituitary gland. Thus, pituitary tumors can cause damage.
- Interal carotid a. aneuyrism can compress optic chiasm
What happens if we have damage to optic chiasm?
Bitemporal hemianopia (loss of vision laterally in both visual fields)
Oculomotor nerve (CN III) Functions
GSE and GVE
- GSE: motor innervation to eye muscles:
- superior, medial, and inferior recti m.
- inferior oblique m.
- levator palpebrae superioris m.
- GVE: carries parasympathetic innervation to the pupil and ciliary muscle.
What tract is followed by the oculomotor nerve?
- Leave the midbrain ->
- pierces the dura lateral to diaphragma sellae ->
- runs in lateral wall of cavernous sinus ->
- enters orbit via superior orbital fissure.
What is the function of the trochlear nerve (CN IV)?
GSE
GSE: motor innervation to the superior oblique muscle of the eye.
What is the tract of the trochlear nerve?
- Exits the dorsal surface of the midbrain ->
- Pierces the dura mater at the margin of the tentorium cerebelli ->
- Runs in the lateral wall the cavernous sinus ->
- Enters the orbit via the superior orbital fissure.
What is the only nerve to exit the dorsal surface of the midbrain?
CN IV (trochlear)
What is the function of the abducens nerve (CN VI)?
GSE
Motor innervation to the lateral rectus m. of the eye
What is the tract of the abducens nerve (CN VI)?
- Emerges from the brainstem at the pontomedullary. junction ->
- Goes thru pontine cistern ->
- pierces of the dura covering the clivus ->
- runs in the cavernous sinus near the ICA ->
- enters the orbit by the superior orbital fissure.
Where is the nucleus of the abducens located?
In the pons.
What are the functions of the trigeminal nerve (CN V)?
SVE and GSA
- Special visceral efferent (SVE): motor innervation to the chewing muscles (derived from pharyngeal arch 1).
- General somatic afferen (GSA)t: sensory from face and scalp.
What is the tract for the trigeminal nerve (CN V)?
Both the motor and sensory portions emerge from the lateral aspect of the pon: trigeminal ganglion is located in the trigeminal cave, lateral to cavernous sinus. Then, it branches into:
- V1 (Opthalmic): passes through the cavernous sinus and enters the orbit of the eye via the superior orbital fissure.
- V2 (Maxillary): passes through the cavernous sinus and exits the skull by the foramen rotundum.
- V3 Mandibular: exits the skull by the foramen ovale- > inferotemporal fossa
The motor portion of the trigeminal nerve exists within which branch?
V3 Mandibular
What is the function of the ophthalmic division of the trigeminal nerve (CN V)?
Sensation from:
- cornea,
- skin of forehead and scalp,
- upper eyelid,
- part of nose (bridge -> point)
- part of nasal cavity.
What is the function of the maxillary division of the trigeminal nerve (CN 5)?
Sensation from
- the skin of the face
- lower eyelid
- cheek
- upper lip
- maxillary teeth
- mucosa of nose and
- maxillary sinus.
What is the function of the mandibular division of the trigeminal nerve (CN V)?
Sensation from the :
- skin of the mandible,
- lower lip side of head (?),
- Mandibular teeth,
- TMJ joint,
- part of oral mucosa,
- anterior 2/3 of tongue
motor innervation to the:
- muscles of chewing (as well as the myelohyoid, anterior belly of the digastric, and the tensor tympani).