Cranial Nerves Flashcards
Cribriform plate diseases
Nasal origin: nasal tumors, destructive rhinitis
Intracranial: esthesioneuroblastoma, cranial trauma (dural tears, CSF rhinorrhea, olfactory bulb separation)
What is the optic nerve derived from?
Outgrowth of brain = white matter tract myelinated by oligodendrocytes
Sequences best for optic nerve identification?
Dorsal images with fat suppression
Where is the optic chasm located?
Ventral to hypothalamus & rostral to hypophyseal infundibulum
In general, how do disease affect the optic nerve?
Cause demyelination
What are the MRI findings of optic nerve disease?
Swelling, altered signal intensity, & contrast enhancement of the optic nerve
What is the common tumor of the optic nerve?
Meningioma (arises from dural sheath)
Exit of olfactory nerve (I)
Cribriform plate (ethmoid bone)
What is important about the trochlear nerve at level of brainstem?
Only CrN to emerge DORSALLY
What are the 3 branches of the trigeminal nerve (V)?
Ophthalmic, Maxillary, Mandibular
Where does the ophthalmic nerve exit?
Orbital fissure
Where does the maxillary nerve exit?
Round foramen, alar canal, & rostral alar foramen
Where does the mandibular nerve exit?
Oval foramen
Mandibular nerve is motor to what?
Muscles of mastication
What are the 6 muscles of mastication?
Masseter, Temporalis, Rostal digastricus, Medial & lateral pterygoids, & mylohyoideus
Where does the abducens nerve exit (VI)?
Orbital fissure
What nerve innervates the caudal belly of the digastricus?
Facial
Where does the facial nerve (VII) exit?
Internal acoustic meatus (along w/ vestibular & cochlear nn)
Name the CrN in order from 1 to 12
1 - Olfactory, 2- Optic, 3 - Oculomotor, 4- Trochlear, 5- Trigeminal, 6- Abducens, 7- Facial, 8- Vestibulocochlear, 9- Glossopharyngeal, 10 - Vagus, 11- Accessory, 12- Hypoglossal
What dysfunction results from CrN 1?
Loss of smell
What is the entrance of CrN 1?
Cribriform foramina
What dysfunction results from CrN 2?
Loss of vision
What 4 things are contained within the orbital fissure?
CrN3 (exrtraoc, ciliary, pupil)
CrN 4 (dorsal obl m)
CrN 5 - ophthalmic branch (sensory to cornea, nasal cavity, & periocular skin)
CrN 6 (motor lateral rectus & retractor bulbi)
What is contained within the rostral alar foramen?
Maxillary artery & maxillary branch of CrN 5
What is contained within the caudal alar foramen?
Maxillary artery
What are the motor & sensory functions of the mandibular branch of CrN 5?
Motor to muscles of mastication
Sensory to rostral tongue, lower cheek, & jae
What is the function of the hypoglossal nerve?
Motor to tongue, vocalization & swallowing
What is the function of the facial nerve?
Motor to muscles of facial expression, taste to rostral 1/3, parasympathetic to salivary glands
What is the function of the glossopharyngeal nerve?
Taste to caudal 1/3, motor to pharynx to allow for swallowing, salivation
What is the function of the vagus nerve?
Motor to pharynx (along w/ CrN 9), larynx (recurrent laryngeal n), parasympathetic to viscera of neck/thorax/abdomen
