CRANIAL NERVES

Question 1

What is Cranial Nerve 1? What are its functional components? Cell bodies? Where does it exit?

Answer 1

1. Olfactory Nerve
2. SVA: smell
3. Cell bodies: nasal mucosa
4. Arises from the nasal mucosa –> cribriform plate –> olfactory bulbs –> Prefrontal Cortex

Question 2

What is Cranial Nerve 2? What are its functional components? Cell bodies? Where does it exit?

Answer 2

1. Optic Nerve
2. SSA: vision, PaNS: pupillary light reflex
3. Ganglion cells
4. Retina –> Optic Nerve –> Optic Chiasm (nasal afferents or temporal visual fields cross over) –> Optic Tracts –> LGN (thalamus) –> Visual Cortex –>
   - M ganglion cells –> 4Ca –>4B –> Dorsal Pathway –> Motion
   - P ganglion cells –> 4Cb –> Ventral Pathway –> Faces, Color, Abstract

Question 3

What is Cranial Nerve 3? What are its functional components? Cell bodies? Where does it exit?

Answer 3

1. Oculomotor
   2.
   GSE: efferents; Superior, Inferior, Medial Rectus; Inferior Oblique (looks up), Levator Palpebrae Superiors (elevates the upper eye lid)
   GVE: Effector of Pupillary Light Reflex. Preganglionic Parasympathetic Fibers –> ciliary muscles
2. GSE: Oculomotor Nucleus
   GVE: Edinger-Westphal
3. Exits via the superior orbital fissure.
   Passes through Cavernous Sinus

Question 4

What passes through the cavernous sinus?

Answer 4

1. Internal Carotid A.
2. CN 3, 4, 6
3. Branches of the trigeminal (V1, V2) are closely associated.

Question 5

What is Cranial Nerve 4? What are its functional components? Cell bodies? Where does it exit?

Answer 5

1. Trochlear Nerve
2. GSE: efferent: Superior Oblique (moves eye downward when in the medial position)
3. Caudal Aspect of DORSAL MIDBRAIN
4. Superior Orbital Fissure. Passes through the Cavernous Sinus.

Question 6

What is Cranial Nerve 5? What are its functional components? Cell bodies? Where does it exit?

Answer 6

1. Trigeminal Nerve. V1/V2/V3
2. GSA, SVE
   GSA: Sensory information: Somatosensory: Face, Palate, Teeth, Gum, Cornea.
   SVE: Muscles of Mastication
3. GSA; the cell bodies: Mesencephalic Nucleus (unconsious proprioception), Chief Nucleus (fine touch), Spinal Trigeminal Nucleus (pain, temperature).
   SVE: Motor Nucleus
4. V1: Ophthalamic: superior orbital fissure
   V2: Mandibular: Ovale
   V3: Maxillary: Rotundum

Question 7

What is Cranial Nerve 6? What are its functional components? Cell bodies? Where does it exit?

Answer 7

1. Abducens Nerve
2. GSE: Abducens - Abduction
3. Posterior Pons
4. Superior Orbital Fissure

Question 8

What is Cranial Nerve 7? What are its functional components? Cell bodies? Where does it exit?

Answer 8

1. Facial Nerve
2.
SVE: Muscles of Facial Expression
GVE: Preganglionic Parasympathetic; submandibular, sublingual, LACRIMAL, nasal, palatine
SVA: Taste from Ant. 2/3 of tongue
GSA: Sensation behind the ear, and EAM
3. 
SVE: Facial Motor Nucleus 
GVE: Superior Salivary Nucleus
SVA: Genticulate Ganglion
GSA: Genticulate Ganglion
4. 
SVA: to the Rostral Solitary Nucleus
GSA: to the Spinal Trigeminal Ganglion

Question 9

What is Cranial Nerve 8? What are its functional components? Cell bodies? Where does it exit?

Answer 9

1. Vestibulocochlear
2. SSA: sound and sight
3. Sound: Cochlear N (ventral). –> Sup. Olivary N –> Inf. Colliculus –> MGN –> Auditory Cortex
   Balance: Vestibular N.
4. Stays within the Skull

Question 10

What are the branches of the Facial Nerve?

Answer 10

Greater Petrosal - Lacrimation
S: Stapedius; controls movement of the stapes thus sound deafening
Chorda Tympani: Taste - gets lost in the ear
Temporal, Zygomatic, Buccal, Mandibular, Cervical

Question 11

What is Cranial Nerve 9? What are its functional components? Cell bodies? Where does it exit?

Answer 11

1. Glossopharyngeal
2. GVE: Preganglionic Parasympathetic: PAROTID GLAND
   SVE: innervates stylopharngeus; elevates upper part of pharynx for speech and swallowing.
   GVA: Responds to changes in BP
   SVA: Afferent Limb of Diaphragm contraction, Taste inputs from Post. 1/3 of tongue.
3. GVE: Inferior Salivatory Nucleus
   SVE: Nucleus aMbiguuS
   GVA: Ganglion in carotid sinus
   SVA: Carotid Body, Nucleus of the Solitary Tract (Rostral)
4. Jugular Foramen

Question 12

What is Cranial Nerve 10? What are its functional components? Cell bodies? Where does it exit?

Answer 12

1. Vagus
   2.
   GSE: 1 muscle of the tongue
   SVE: Innervates Pharynx, Soft Palate –> speech
   GVE: PaNS innervation to heart, body, peristalsis
   GVA: Sensory Information from Abd. and Thoracic viscera, Baroreflex (aortic arch)
   SVA: Taste from epiglottis, pharynx
   GSA: Somatosensory Information from behind the ear and EAM.
2. SVE: Nucleus Ambiguus
   GVA: aortic arch
3. Jugular Foramen

Question 13

What is Cranial Nerve 11? What are its functional components? Cell bodies? Where does it exit?

Answer 13

1. Spinal Accessory Nerve
2. SVE: sternomastoid, trapezius; Turning, Shrugging, Nodding, Lifting head
3. C1 - C5 ventral horn cells
4. Jugular Foramen

Question 14

What is Cranial Nerve 12? What are its functional components? Cell bodies? Where does it exit?

Answer 14

1. Hypoglossal
2. GSE: Tongue Muscles except for one.
3. Hypoglossal N.
4. Hypoglossal Canal