Unit 3

Question 1

Where do cranial nerves attach?

Answer 1

brainstem (midbrain, pons, medulla)

exceptions: CN I and II attach directly to brain, CN XI originates in SC but then enters the spinal cavity

Question 2

How do cranial nerves enter/exit the cranial cavity?

Answer 2

openings in skull (foramina, meatus, fissures, or canals)

Question 3

Cranial nerve nuclei

Answer 3

are sensory or motor but NEVER both
Groups of neurons in which sensory fibers terminate OR
Groups of neurons from which motor fibers originate
collection of cell bodies within CNS = nucleus
cranial nerves can have both nuclei and ganglia

Question 4

3 letter classification scheme of nerve impulses

Answer 4

1. G or S; general or special
2. S or V; somatic or visceral
3. A or E; afferent or efferent

Question 5

1. G or S

Answer 5

general - impulses can be transmitted by cranial OR spinal nerves
special - impulses can ONLY be transmitted by CN

Question 6

2. S or V

Answer 6

somatic - impulses that transmit to skeletal muscle and skin; voluntary transmission
visceral - impulses that transmit to digestive sys, smooth muscle, cardiac muscle, vascular system, and glands; involuntary

Question 7

3. A or E

Answer 7

afferent - impulses transmitted from body to CNS: sensory

efferent - impulses transmitted from CNS to body: motor neurons to skeletal and smooth muscle; secretomotor to glands

Question 8

GSA

Answer 8

general somatic afferent

sensation from muscles, tendons, joints

Question 9

GVA

Answer 9

general visceral afferent

sensation from visceral tissues

Question 10

GSE

Answer 10

general somatic efferent

motor to skeletal muscle

Question 11

GVE

Answer 11

general visceral efferent

motor to visceral tissues

Question 12

SSA

Answer 12

special somatic afferent

“special sensations” including vision, audition, and balance

Question 13

SVA

Answer 13

special visceral afferent

“special sensations” including taste, and olfaction (these ones involve chemical reactions)

Question 14

SVE

Answer 14

special visceral efferent

motor to “special viscerally-related” skeletal muscles…

Question 15

Why is SSE not a category?

Answer 15

not special;

considered GSE

Question 16

Cranial Nerves

Answer 16

Some say marry money but my brother says big brains matter more
CN I – Olfactory Nerve: sensory SVA
CN II – Optic Nerve: sensory SSA
CN III – Oculomotor Nerve: motor GSE + GVE
CN IV – Trochlear Nerve: motor GSE
CN V – Trigeminal Nerve: both GSA + SVE
CN VI – Abducens Nerve: motor GSE
CN VII – Facial Nerve: both GSA + GVA + SVA + SVE + GVE
CN VIII – Vestibulocochlear Nerve: sensory SSA
CN IX – Glossopharyngeal Nerve: both GSA + GVA + SVA + SVE + GVE
CN X – Vagus Nerve: both GSA + GVA + SVA + SVE + GVE
CN XI – (Spinal) Accessory Nerve: motor SVE
CN XII – Hypoglossal Nerve: motor GSE

Question 17

Cranial Sensory Nerves

Answer 17

CN I – Olfactory Nerve: SVA – smell (olfaction)
CN II – Optic Nerve: SSA – vision
CN VIII – Vestibulocochlear Nerve: SSA – balance/orientation, hearing

Question 18

CN I

Answer 18

olfactory: smell (SVA), involves chem rxn -> V

* *attaches directly to brain, NOT brainstem

Question 19

CN II

Answer 19

optic: vision (SSA); no chem rxn -> S

* * attaches directly to brain, NOT brainstem

Question 20

CN VIII

Answer 20

vestibulocochlear nerve: sensory (SSA) balance/orientation, hearing
nuclei in pons and medulla
passes thru internal auditory meatus

Question 21

Cranial Nerves: Motor

Answer 21

CN III – Oculomotor Nerve: GSE + GVE – motor to muscles of the eye, and parasympathetic to the ciliary muscles and pupil
CN IV – Trochlear Nerve: GSE – motor to the superior oblique muscle of the eye
CN VI – Abducens Nerve: GSE – motor to the lateral rectus muscle of the eye
“3,4, 6 -> eyes do tricks”
CN XI – (Spinal) Accessory Nerve: SVE – motor to the sternocleidomastoid muscle and trapezius muscle
CN XII – Hypoglossal Nerve: GSE – motor to the muscles of the tongue (except palatoglossus)

Question 22

CN III

Answer 22

oculomotor: motor (GSE and GVE)
motor to muscles of the eye, and parasympathetic to the ciliary muscles and pupil
*nuclei in midbrain, passes through superior orbital fissure, then divides in superior and inferior branch

Question 23

CN III superior branch

Answer 23

motor (GSE)

innervates superior rectus and levator palpebrae muscles

Question 24

CN III inferior branch

Answer 24

motor (GSE)
innervates medial and inferior rectus muscles and inferior oblique muscle
parasympathetic motor (GVE)
preganglionic parasymp fibers synapse in ciliary ganglion -> short ciliary nerves -> innervate ciliary muscles of eye and pupil sphincter

Question 25

CN IV

Answer 25

trochlear GSE – motor to the superior oblique muscle of the eye nucleus in midbrain * passes through superior orbital fissure ** only CN to attach on dorsum of brainstain

Question 26

CN VI

Answer 26

abducens | GSE – motor to the lateral rectus muscle of the eye

Question 27

CN XI

Answer 27

(Spinal) Accessory Nerve: SVE – motor to the sternocleidomastoid muscle and trapezius muscle - motor cell bodies in SC (C1-C5), ascend via SC, enter cranial cavity via foramen magnum, exit via jugular foramen

Question 28

CN XII

Answer 28

hypoglossal Nerve: GSE – motor to the muscles of the tongue (except palatoglossus) - nucleus in medulla: passes through hypoglossal canal

Question 29

Cranial nerves: both

Answer 29

CN V – Trigeminal Nerve: GSA + SVE CN VII – Facial Nerve: GSA + GVA + SVA + SVE + GVE CN IX – Glossopharyngeal Nerve: GSA + GVA + SVA + SVE + GVE CN X – Vagus Nerve: GSA + GVA + SVA + SVE + GVE These cranial nerves have multiple fiber types They will carry multiple types of impulses They will have multiple nuclei They will have the most complicated pathways

Question 30

CN V

Answer 30

trigeminal: Motor root: Motor to muscles of mastication (SVE) Sensory root: Sensory from face, sinuses, teeth (GSA) - nuclei for both in pons - roots pass through middle cranial fossa - sensory root: trigeminal ganglion, 3 branches: opthalmic (V1), maxillary (V2), mandibular (V3) - motor root joins mandibular division

Question 31

V1

Answer 31

opthalmic division of CN V sensory (GSA) - passes through superior orbital fissure to enter orbit - divides into frontal, nasociliary, and lacrimal nerves - supplies eyeball, conjunctiva, part of nasal cavity mucuous membrane, and from upper eyelids, eyebrow, forehead, anterior scalp, nose - assoc with ciliary ganglion

Question 32

V2

Answer 32

maxillary division of CN V sensory (GSA) - passes through foramen rotundum to enter pterygopalatine fossa - enters orbit via inferior orbital fissure; terminal branch exits via infraorbital foramen - sensory from upper teeth/gums, mucosa, skin of upper cheek, lip, side of nose, lower eyelid, upper side of head - assoc with pterygopalatine ganglion

Question 33

V3

Answer 33

mandibular division of CN V mixed nerve: GSA and SVE combines w/ motor root of CN V after passing through foramen ovale branches: auriculotemporal, lingual, inferior alveolar nerves - sensory: from lower teeth/gums, mucus membranes, skin of cheeks, lower lips, chin, ext ear, middle scalp - motor: innervates mastication muscles, tensor tympani, tensor veli palatinis, mylohyoid muscle, ant belly of digastric muscle - assoc w/ submandibular ganglion and otic ganglion

Question 34

CN VII

Answer 34

Facial Nerve: (GSA, GVA, SVA, SVE, GVE) - Motor: Muscles of facial expression - Parasympathetic “Secretomotor”: Submandibular, sublingual, and lacrimal glands - Sensory: Taste for anterior 2/3 of tongue, soft palate; via chorda tympani nerve; also sensory from skin around ear canal/ear drum exit cranial cavity via internal acoustic meatus -> go to geniculate ganglion, splits into divisions

Question 35

CN IX

Answer 35

Glossopharyngeal Nerve: Motor: Stylopharyngeus muscle Parasympathetic “Secretomotor”: Parotid gland Sensory: Taste posterior 1/3 of tongue, sensory from pharynx, external ear, middle ear cavity, carotid body/sinus

Question 36

CN X

Answer 36

Vagus Nerve: Motor: Palate, pharynx (except stylopharyngeus), larynx, palatoglossus muscle Parasympathetic: Bronchial tree, heart, GI tract Sensory: External acoustic meatus, taste from epiglottis and palate, visceral sensory from pharynx, larynx, bronchial tree, heart, GI tract

Question 37

Sympathetic Fibers

Answer 37

``` Sympathetic Trunk (presynaptic sympathetic fibers) only extends the length of the spinal cord – it does NOT enter the cranial cavity Superior Cervical Ganglion – contains all of the synapses for the major sympathetic fibers going into the head Postsynaptic sympathetic fibers will then wrap around blood vessels (Internal Carotid Artery) to get into the cranial cavity Then they associate (travel with) cranial nerves to get to their target organ ```

Question 38

Parasympathetic fibers

Answer 38

Preganglionic parasympathetic fibers – cell bodies are in the brainstem – travel out with four of the cranial nerves Oculomotor (CN III) Facial (CN VII) Glossopharyngeal (CN IX) Vagus (CN X) There are four parasympathetic ganglia in the head that these will synapse in Preganglionic PS fibers traveling with Vagus will synapse near their target organs throughout the body (NOT in the head!)

Question 39

4 parasympathetic ganglia in head

Answer 39

The four parasympathetic ganglia in the head are associated with branches of the Trigeminal Nerve (CN V) Oculomotor (CN III) – Ciliary Ganglion – V1 Facial (CN VII) – Pterygopalatine Ganglion – V2 Facial (CN VII) – Submandibular Ganglion – V3 Glossopharyngeal (CN IX) – Otic Ganglion – V3