Cranial Nerves Flashcards
How many pairs of cranial nerves are there?
12
What is the name of the first cranial nerve?
Olfactory
What is the pathway of the olfactory nerve?
Passes through the cribriform plate and enters the olfactory bulb in the anterior cranial fossa
What is the role of the olfactory nerve?
Special sensory (smell)
What is the consequence of a fractured cribriform plate?
Olfactory nerve tear causing anosmia
What is the name of the second cranial nerve?
Optic
What is the pathway of the optic nerve?
Enters via optic canal to join optic chiasma
What is the role of the optic nerve?
Special sensory (vision)
What are the clinical application of the optic nerve?
Increase CSF pressure causes papilloedema
Right optic nerve section causes right eye blindness
Optic chiasma section causes peripheral vision loss
Right optic tract section causes left temporal and right nasal field blindness
What is the name of the third cranial nerve?
Oculomotor
What is the pathway of the oculomotor nerve?
Emerges from midbrain
Exits via superior orbital fissure
What is the role of the oculomotor nerve?
Somatic motor control of extra ocular muscles and eyelid
Parasympathetic control of pupil constriction and ciliary muscle causing lens accommodation
What are the clinical signs of an oculomotor nerve problem?
Ptosis
No pupillary reflex
No lens accommodation
Eyeball abducted and pointing down
What is the name of the fourth cranial nerve?
Trochlear
What is the pathway of the trochlear nerve?
Emerges from dorsal surface of midbrain
Exits via superior orbital fissure
What is the role of the trochlear nerve?
Somatic motor control of superior oblique
What are the clinical signs of trochlear nerve problems?
Diplopia
What is the name of the fifth cranial nerve?
Trigeminal
What are the 3 branches of the trigeminal nerve?
Ophthalmic (V1)
Maxillary (V2)
Mandible (V3)
What is the pathway of the ophthalmic nerve?
Emerges from pons, travels through trigeminal ganglion
Exits via superior orbital fissure
What is the role of the ophthalmic nerve?
Sensory into from cornea, forehead, scalp, eyelids, nose, mucosa from nasal cavity and sinuses