Nerves 1

Question 1

Cranial nerves

Answer 1

12 pairs

Emerge from ventrolateral surface of brain (ex. CN VI from dorsal surface)

Question 2

CN I

Answer 2

Olfactory nerve, purely sensory

From nasal mucosa to olfactory bulbs, passing cribriform plate of ethmoid bone

Question 3

CN II

Answer 3

Optic nerve

From retina, pass optic canal, crosses over at optic chiasm, continues as optic tract till occipital lobe

Question 4

Crossing over

Answer 4

Inf. nasal fibers cross in ant. chiasm
Sup. Nasal fibers cross in pos. chiasm
Temporal fibers continue on their side
Continues as optic tract to LGM

Question 5

Cavernous sinus relation to CN

Answer 5

Network of venous space surrounding pituitary gland.
CN III, IV, VI pass superior orbital fissure
Before SOF they pass cavernous sinus where they may all be damaged.

Question 6

CN III

Answer 6

Oculomotor nerve [Motor/parasympathetic]
From ventral midbrain through superior orbital fissures where if branches Sup./Inf.
Superior: SR, LPS
Inferior: MR, IR, IO, ciliary ganglion
Iris constriction, lens shape (parasympathetic)

Question 7

Extraocular muscles innervation

Answer 7

LR6(SO4)3
LR6 (Lateral rectus muscle: CN VI), SO4 (Superior oblique muscle: CN IV), (SO4)3 : all other extraocular muscles = CN III

Question 8

CN IV

Answer 8

Trochlear nerve
From dorsal midbrain to superior orbital fissure (lowest of nerves in SO)
Purely motor, to superior oblique

Question 9

CN V

Answer 9

From pons through trigeminal ganglion (where division occurs) to face
Trigeminal nerve, 3 divisions, mainly sensory
Ophthalmic V1 passes SO fissure
Maxillary V2 passes foramen rotundum
Mandibular V3 passes foramen ovale

Question 10

CN V1

Answer 10

Ophthalmic branch: senses eye and upper face.
Passes SO fissure from trigeminal ganglion
Splits into 3 branches:
Lacrimal: passes lateral wall to lacrimal gland/conjunctiva
Frontal: passes orbit roof to LPS, splits to supraorbital / supratrochlear branch
Nasociliary: passes medial wall, splits to long/short ciliary and infratrochlear nerve
*sensory reverse direction

Question 11

Nasociliary nerves

Answer 11

Branch of ophthalmic branch of CN V. branches into long/short ciliary and infratrochlear nerves
Long ciliary 2x: enter sclera near either side of ON to cornea/conjunctiva/limbus/sclera, Sharp pain
Short ciliary 10x: Exit ciliary ganglion near ON, enter sclera to iris/ciliary body/choroid, dull pain
*Sensory so reversed direction

Question 12

CN V2:

Answer 12

Maxillary: temple, mid face.
from trigeminal ganglion, enters Foramen rotundum, branches in pterygopalatine fossa adjacent to inferior orbital fissure.
Forms zygomatic and infraorbital branch
*sensory reverse direction

Question 13

Infraorbital branch

Answer 13

Branch of maxillary branch of CN V
Branches in pterygopalatine fossa, enters inferior orbital fissure, follows infraorbital groove, enters infraorbital canal, exits infraorbital foramen to face.
*sensory reverse direction

Question 14

Zygomatic branch

Answer 14

Branch of maxillary branch of CN V
Branches off in pterygopalatine fossa, enters inferior orbital fissure to zygomatic bone. Branch of this joins lacrimal nerve
*sensory reverse direction

Question 15

CN V3

Answer 15

Mandibular: lower face.
Branch from trigeminal ganglion passes foramen ovale to jaw.
*sensory reverse direction

Question 16

CN VI

Answer 16

Abducens nerve
From pons through SO fissure within annulus of zinn.
Pure motor to Lateral rectus
LR6(SO4)3

Question 17

CN VII

Answer 17

Facial nerve, motor, sensory, and parasympathetic
From pons, through internal acoustic meatuses, partially emerging through stylomastoid foramina to lateral face
Motor: facial expression (orbicularis oculi)
Parasympathetic: lacrimal / salivary
Sensory: taste

Question 18

CN VII motor branch

Answer 18

Enters internal auditory meatus (with CN VIII)

Exits stylomastoid foramen below ear, branches in parotid gland, supplies face muscles including orbicularis oculi.

Question 19

Order of nerves passing into orbit from top to bottom

Answer 19

Above annulus of Zinn
Lazy French Tarts: Lacrimal, frontal, trochlear (CN V5, IV)
Within annulus of Zinn
Sit naked in anticipation: Sup. III, Nasociliary, Inf. III, Abducent (CN III, V1, VI, III)

Question 20

Order of CN from below, Ant. to Pos. wish how to tell which is which

Answer 20

Olfactory: Cerebrum. highest
Optic: Cerebrum. has chiasm
Oculomotor: Midbrain. under optic, between trochlear
Trochlear: Midbrain. around oculomotor from behind, small above trigeminal.
Trigeminal: Pons. large with branches
Abducent: Pons. medial, below and between trigeminal
Facial: Pons. small, next to large CN VIII

Question 21

Ciliary ganglion

Answer 21

Nasociliary branch and Inf. branch of oculomotor join and form short ciliary nerves