Cranial Nerves

Question 1

What are the cranial nerves?

Answer 1

Ooh, ooh, ooh to touch and feel very good velvet. Such heaven!

CN I: Olfactory
CN II: Optic
CN III: Oculomotor
CN IV: Trochlear
CN V: Trigeminal
CN VI: Abducent
CN VII: Facial
CN VIII: Vestibulocochlear
CN IX: Glossopharyngeal
CN X: Vagus
CN XI: Spinal Accessory
CN XII: Hypoglossal

Question 2

Which cranial nerves provide both sensory and motor innervation?

Answer 2

V, VII, IX, X

CN V: Trigeminal
CN VII: Facial
CN IX: Glossopharyngeal
CN X: Vagus

Question 3

What is the function of GSE fibers?

Answer 3

GSE

General Somatic Efferent: motor innervation from the brain to voluntary muscle, skin, and joints

Question 4

What is the function of GSA fibers?

Answer 4

GSA

General Somatic Afferent: sensory innervation from skin, muscle, joints to the brain

Question 5

What is the function of GVE fibers?

Answer 5

GVE

General Visceral Efferent: Involuntary/ Parasympathetic motor innervation to blood vessels, guts, and glands

Question 6

What is the function of GVA fibers?

Answer 6

GVA

General Visceral Afferent: sensory/pain innervation from internal organs to brain

Question 7

What is the function of SVE fibers?

Answer 7

SVE

Special Visceral Efferent: voluntary motor innervation from brain to any muscle that is derived from the pharyngeal arches

Question 8

What is the function of SVA fibers?

Answer 8

SVA (smell/taste)

Special Visceral Afferent: special taste and smell innervation from tongue/nose to brain

Question 9

What is the function of SSA fibers?

Answer 9

SSA (see and hear that ass clap, but balance)

Special Somatic Afferent: special vision, hearing, and balance from ears/eyes to brain

Question 10

What are the only 2 nerves with the SSA functional component?

Answer 10

CN II (optic) and CN VIII (Vestibulocochlear)

Question 11

Which nerves have parasympathetic function?

Answer 11

GVE: III, VII, IX, X (3,7,9,10) - only cranial nerves with parasympathetic function

Question 12

Which nerves exit the jugular foramen?

Answer 12

9,10,11 - jugular foramen

Question 13

Which nerves exit the superior orbital fissure?

Answer 13

3,4,V1, 6 - superior orbital fissure

Question 14

4 Unique features of the trochlear nerve?

Answer 14

Only nerve that exits the back of the brain

Only nerve in which all lower motor neurons decussate (intersect) (i.e. left side of brain does the right eye, and vice versa)

Longest intracranial course (Significant because of there is any trauma, this is most exposed and open to damage)

Smallest Number of axons

Question 15

What are the branches of the trigeminal nerve (CN V)?

Answer 15

Ophthalmic (V1)

Maxillary (V2)

Mandibular (V3)

Question 16

What are the routes of the branches of the trigeminal nerve?

Answer 16

STANDING ROOM ONLY, STUPID

Ophthalmic (V1) - superior orbital fissure

Maxillary (V2) - foramen rotundum

Mandibular (V3) - foramen ovale

Middle meningeal artery - foramen spinosum

Question 17

True or False: CN V has parasympathetic innervation?

Answer 17

False. CN 5 technically has no parasympathetic function, but CN 3,7,9,10 all have parasympathetic function and their fibers need to jump on branches of 5 to get to their destinations

Question 18

What is right oculomotor nerve palsy?

Answer 18

Dysfunction in the oculomotor nerve that results in ptosis (drooping eyelid), down/outward gaze, dilated pupil.

Question 19

What if there is a lesion to CN 11 on the left side?

Answer 19

If there’s a lesion to the right CN 11, then you cannot turn head to the left. (SCM turns head to the OPPOSITE side.

Question 20

What is left abducent nerve palsy?

Answer 20

Left eye will not abduct (lateral rectus innervation destroyed).

Question 21

What if there is a lesion of the left hypoglossal nerve?

Answer 21

The tongue will point toward the lesion.