Unit 3 Flashcards
Where do cranial nerves attach?
brainstem (midbrain, pons, medulla)
exceptions: CN I and II attach directly to brain, CN XI originates in SC but then enters the spinal cavity
How do cranial nerves enter/exit the cranial cavity?
openings in skull (foramina, meatus, fissures, or canals)
Cranial nerve nuclei
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
3 letter classification scheme of nerve impulses
- G or S; general or special
- S or V; somatic or visceral
- A or E; afferent or efferent
- G or S
general - impulses can be transmitted by cranial OR spinal nerves
special - impulses can ONLY be transmitted by CN
- S or V
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
- A or E
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
GSA
general somatic afferent
sensation from muscles, tendons, joints
GVA
general visceral afferent
sensation from visceral tissues
GSE
general somatic efferent
motor to skeletal muscle
GVE
general visceral efferent
motor to visceral tissues
SSA
special somatic afferent
“special sensations” including vision, audition, and balance
SVA
special visceral afferent
“special sensations” including taste, and olfaction (these ones involve chemical reactions)
SVE
special visceral efferent
motor to “special viscerally-related” skeletal muscles…
Why is SSE not a category?
not special;
considered GSE
Cranial Nerves
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
Cranial Sensory Nerves
CN I – Olfactory Nerve: SVA – smell (olfaction)
CN II – Optic Nerve: SSA – vision
CN VIII – Vestibulocochlear Nerve: SSA – balance/orientation, hearing
CN I
olfactory: smell (SVA), involves chem rxn -> V
* *attaches directly to brain, NOT brainstem
CN II
optic: vision (SSA); no chem rxn -> S
* * attaches directly to brain, NOT brainstem
CN VIII
vestibulocochlear nerve: sensory (SSA) balance/orientation, hearing
nuclei in pons and medulla
passes thru internal auditory meatus
Cranial Nerves: Motor
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)
CN III
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
CN III superior branch
motor (GSE)
innervates superior rectus and levator palpebrae muscles
CN III inferior branch
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
CN IV
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
CN VI
abducens
GSE – motor to the lateral rectus muscle of the eye
CN XI
(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
CN XII
hypoglossal Nerve: GSE – motor to the muscles of the tongue (except palatoglossus)
- nucleus in medulla: passes through hypoglossal canal
Cranial nerves: both
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
CN V
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
V1
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
V2
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
V3
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
CN VII
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
CN IX
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
CN X
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
Sympathetic Fibers
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
Parasympathetic fibers
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!)
4 parasympathetic ganglia in head
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
