Chapter 15: Part II (Cranial Nerves) SYDNEY 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
condition caused by oculomotor nerve damage
oculomotor palsy
what happens during oculomotor palsy?
-ptosis (drooping eyelid)
-abducted and inferiorly directed pupil (down and out)
-dilated pupil (loss of parasympathetic)
-no pupillary light reflex
condition caused by abducens nerve damage
abducent palsy
what happens during abducent palsy?
-long intracranial course
-inability to abduct affected eye
-diplopia (double vision)
pathway of CN VII (facial nerve)
-somatic motor axons leave the pons and enter the temporal bone through the internal acoustic meatus
-then projects through the temporal bone, and emerges through the stylomastoid foramen to supply the musculature
somatic motor function of CN VII (facial nerve)
motor to muscles of facial expression
sensory function of CN VII (facial nerve)
taste from anterior two-thirds of tongue
-sensory axons travel from the tongue via chorda tympani branch
-join lingual nerve
parasympathetic motor function of CN VII (facial nerve)
increases secretions of the lacrimal gland of the eye as well as the sublingual and submandibular salivary glands
clinical of CN VII (facial nerve)
-lesion near origin
-long bony path
features of long origin
loss of taste
Bell’s palsy (motor to entire side of face)
features of long bony path
viral inflammation
sensory functions of CN VIII (vestibulocochlear nerve)
-cochlear branch conducts impulses for: hearing
-vestibular branch conducts impulses for: equilibrium
pathway of CN VIII (vestibulocochlear nerve)
the vestibular and cochlear branches merge and together enter cranial cavity through internal acoustic meatus
nerves of the CN VIII (vestibulocochlear nerve)
-vestibular nerve
-cochlear nerve
features of the vestibular nerve
-maculae (position)
-ampullae of semicircular canals (rotational)
feature of cochlear nerve
spinal ganglion
sensory function of CN IX (glossopharyngeal nerve)
general sensation and taste to oropharynx and posterior 1/3 of tongue
somatic motor function of CN IX (glossopharyngeal nerve)
innervates stylopharyngeus (pharynx muscle)
parasympathetic motor function of CN IX (glossopharyngeal nerve)
increases secretion of parotid salivary glands
pathway of CN IX (glossopharyngeal nerve)
sensory axons travel from posterior 1/3 of tongue and carotid bodies along nerve through the inferior or superior ganglion into the jugular foramen
clinical of glossopharyngeal nerve
•Rarely injured alone
• Jugular Foramen Syndrome
- Includes CN IX. X. and XI
• Involved in sensory limb of gag reflex
- loss of reflex on affected side
“curtain sign”
What artery does the vagus nerve (CN X) follow?
Carotid artery
Parts of carotid artery
- Carotid sheath
- Branches to pharynx, heart, bronchi, larynx
Features of vagus nerve (CN X)
• Esophageal plexus in
Thorax
• Vagal trunks in abdomen
- Stomach, small intestines, part of large intestines
Is vagus nerve (CN X) sympathetic or parasympathetic?
Parasympathetic
- thoracic and abdominal viscera to left colic flexure
Features of the mouth relating to the Vagus nerve (CN X)
• Muscles of pharynx & soft palate (gag reflex)
• Taste from root of tongue
What type of sensory in the thorax and abdomen from the vagus nerve (CN X)?
• Visceral sensory in thorax and abdomen
Parts of the spinal accessory nerve (CN XI)
• Jugular Foramen
• Motor to
- Sternocleidomastoid m.
- Trapezius
Functions of the hypoglossal nerve (CN XI)
• Motor to intrinsic and extrinsic muscles of the longue
• Paralysis of tongue if damaged
Cranial nerves broken down into cranial nerve fibers:
I. Olfactory
II. Optic
III. Oculomotor
IV. Trochlear
V. Trigeminal
VI. Abducent
VII. Facial
VIII. Vestibulochochlear
IX. Glossopharyngeal
X. Vagus
XI. Spinal Accessory
XII. Hypoglossal
Sensory (Some)
Sensory (Say)
Motor (Marry)
Motor (Money)
Both (But)
Motor (My)
Both (Brother)
Sensory (Says)
Both (Big)
Both (Brains)
Motor (Matter)
Motor (More)
