Cranial Nerves Flashcards
What are the twelve cranial nerves?
One-Olfactory Two-Optic Three-Oculomotor Four-Trochlear Five-Trigeminal (ophthalmic, maxillary and mandibular branches) Six-Abducens Seven-Facial Eight-Vestibulocohlear Nine-Glossopharyngeal Ten-Vagus Eleven-Accessory Twelve-Hypoglossal
What is the pathway of the olfactory nerve?
Starts at olfactory bulb in anterior cranial fossa then goes through foramina in cribriform plate to reach the olfactory epithelium where it expresses as receptors.
What clinical pathology can affect the olfactory nerve?
A fractured cribriform plate from trauma could tear olfactory nerve fibres and cause anosmia.
What is the pathway of the optic nerve?
Starts at posterior eyeball and travels through optic canal to the optic chiasm then the optic tract to the posterior part of the brain.
What are some clinical pathologies that affect the optic nerve?
Increase in CSF pressure can cause papilledema.
Section of optic nerve, optic chiasm or optic tract can cause different kinds of blindness.
What is the pathway for the oculomotor nerve?
Emerges from the midbrain to emerge from the superior orbital fissure.
What are the two components of the oculomotor nerve?
Somatic Motor to control the muscles of the eye
Visceral Motor-Parasympathetic to constrict the pupil and control the ciliaris muscle.
What are some clinical presentations of the oculomotor pathology?
Ptosis
Eyeball abducted and pointing down
No pupillary reflex
No accommodation of the lens
What is the pathway of the trochlear nerve?
From the dorsal surface of the midbrain then goes through the superior orbital fissure.
What is the component of the trochlear nerve?
Somatic motor for controlling the superior oblique
What is a clinical presentation of trochlear nerve pathology?
Diplopia when looking down (especially noticed going down stairs)
What is the pathway of the abducent nerve?
What is its component?
Emerges from between the medulla and pons to exit from the superior orbital fissure
Somatic Motor
What is a clinical presentation of abducent nerve pathology?
Diplopia from medial deviation of affected eye.
Where does the trigeminal nerve emerge from and which branch of it has more than one component?
Emerges from the pons
All branches have general sensory function but only the mandibular branch has somatic motor for innervation of muscles of mastication, digastric muscle and tensor tympani.
What are some clinical presentations of trigeminal nerve pathology?
Trigeminal nerve neuralgia
Muscles of mastication paralysis
Loss of face sensation
Loss of sneezing and corneal reflex