Nerves 1 Flashcards
Cranial nerves
12 pairs
Emerge from ventrolateral surface of brain (ex. CN VI from dorsal surface)
CN I
Olfactory nerve, purely sensory
From nasal mucosa to olfactory bulbs, passing cribriform plate of ethmoid bone
CN II
Optic nerve
From retina, pass optic canal, crosses over at optic chiasm, continues as optic tract till occipital lobe
Crossing over
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
Cavernous sinus relation to CN
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.
CN III
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)
Extraocular muscles innervation
LR6(SO4)3
LR6 (Lateral rectus muscle: CN VI), SO4 (Superior oblique muscle: CN IV), (SO4)3 : all other extraocular muscles = CN III
CN IV
Trochlear nerve
From dorsal midbrain to superior orbital fissure (lowest of nerves in SO)
Purely motor, to superior oblique
CN V
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
CN V1
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
Nasociliary nerves
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
CN V2:
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
Infraorbital branch
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
Zygomatic branch
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
CN V3
Mandibular: lower face.
Branch from trigeminal ganglion passes foramen ovale to jaw.
*sensory reverse direction
CN VI
Abducens nerve
From pons through SO fissure within annulus of zinn.
Pure motor to Lateral rectus
LR6(SO4)3
CN VII
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
CN VII motor branch
Enters internal auditory meatus (with CN VIII)
Exits stylomastoid foramen below ear, branches in parotid gland, supplies face muscles including orbicularis oculi.
Order of nerves passing into orbit from top to bottom
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)
Order of CN from below, Ant. to Pos. wish how to tell which is which
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
Ciliary ganglion
Nasociliary branch and Inf. branch of oculomotor join and form short ciliary nerves
