Chapter 15: Part II (Cranial Nerves) Flashcards
cranial nerves pass through _________ and it’s sheath is derived from what (these are the features of it)
-pass through cranial openings
-sheath derived from cranial meninges
functions of cranial nerves
motor, sensory, special sensory
how many pairs of cranial nerves? how are they numbered?
-12 pairs
-numbered based on origin from brain
name the 12 cranial nerves
(mnemonic to help remember cranial nerves)
(oh) olfactory, CN I
(once) optic, CN II
(one) oculomotor, CN III
(takes) trochlear, CN IV
(the) trigeminal, CN V
(anatomy) abducens, CN VI
(final) facial, CN VII
(very) vestibulocochlear, CN VIII
(good) glossopharyngeal, CN IX
(vacations) vagus, CN X
(are) [spinal] accessory, CN XI
(heavenly!) hypoglossal, CN XII
sensory function of CN I (olfactory nerve) & features
-sensory function: smell
-as many as 20 bundles/side
-passes through the cribriform plate
-enters olfactory bulb at end of olfactory tract
sensory function of CN II (optic nerve) & features
-sensory function: sight
-CNS tracts (part of the brain)
-optic canal
-fibers cross in optic chiasm (medial 1/2 pass to opposite side)
-optic tract
features of optic nerve clinical
-only in myelinated in sclera (oligodendrocytes not schwann cells)
-vulnerable to CNS demyelinating diseases (multiple sclerosis)
somatic motor function of CN III (oculomotor nerve)
supplies 5 extrinsic eye muscles:
-superior rectus
-inferior rectus
-medial rectus
-inferior oblique
-levator palpebrae superioris
which eye muscle uplifts the eye?
levator palpebrae
parasympathetic motor function of CN III (oculomotor nerve)
-makes pupil constrict
-ciliary body changes lens for near vision
somatic motor function of CN IV (trochlear nerve)
supplies superior oblique to move eye inferiorly and laterally
pathway of CN IV (trochlear nerve)
leaves cranium via superior orbital fissure and travels to superior oblique muscle
sensory function of CN V (trigeminal nerve)
general sensory nerve to the head
3 branches of CN V (trigeminal nerve)
-ophthalmic nerve
-maxillary nerve
-mandibular nerve
which branch of the CN V (trigeminal nerve) are the somatic motor fibers in?
mandibular branch
somatic motor function of CN V (trigeminal nerve)
innervates muscle of mastication
somatic motor function of CN VI (abducens nerve)
innervates lateral rectus for eye abduction
pathway of CN VI (abducens nerve)
leaves cranium through superior orbital fissure and travels to lateral rectus muscle
what is ocular palsies?
damage to ocular nerves
how can ocular palsies occur?
-may be driven by increase in cranial pressure
-examples: cranial hemorrhage, brain tumor