MRI cranial nerves Flashcards
(23 cards)
Which cranial nerves are usually consistently visualized in MRI?
II, III, V, and VIII
These nerves are typically isointense to gray matter on T1 and T2.
Where is the nucleus of the hypoglossal nerve (CN XII) located?
In the medulla adjacent to midline in the floor of the 4th ventricle
What is the function of the hypoglossal nerve (CN XII)?
Motor to extrinsic and intrinsic muscles of the tongue
Through which anatomical structures do cranial nerves IX, X, and XI exit the brain?
Jugular foramen and tympano-occipital fissure
Where does the vestibulocochlear nerve (CN VIII) exit the brain?
Through the internal acoustic meatus
What is the exit path of the facial nerve (CN VII)?
Through internal acoustic meatus to the facial canal, to the stylomastoid foramen
Which cranial nerves exit the brain through the orbital fissure?
Oculomotor nerve (CN III), Trochlear nerve (CN IV), Ophthalmic branch of trigeminal nerve (CN Voph), Abducens nerve (CN VI)
Also internal carotid artery
What are the exit points for the branches of the trigeminal nerve (CN V)?
Ophthalmic branch: orbital fissure, Maxillary branch: trigeminal canal to round foramen to alar canal, Mandibular branch: trigeminal canal to oval foramen
Which cranial nerve exits through the optic canal?
Optic nerve (CN II)
What is the exit point for the olfactory nerves (CN I)?
Through cribriform plate
What is noted about the contrast enhancement of the trigeminal ganglia and nerve?
Mild contrast enhancement
What diseases can affect the olfactory nerve?
Nasal cavity disease extending into cranial vault, neoplasia involving the olfactory bulb
What comprises the white matter tracts of the diencephalon related to the optic nerve?
Retinal ganglion cell axons
What are the MRI features of optic neuritis?
Unilateral or bilateral enhancement of optic nerves and chiasm after gadolinium injection, possible enlargement of optic chiasm
What type of tumor is typically T2 hyperintense and strongly contrast enhancing in optic nerve diseases?
Retrobulbar meningioma
What are the characteristics of idiopathic oculomotor neuropathy?
Unilateral areflexive mydriasis, smaller palpebral fissure due to ptosis, neuromuscular dorsolateral strabismus, external ophthalmoparesis
What MRI features are associated with idiopathic trigeminal neuropathy?
Diffuse enlargement of the trigeminal nerve, T1 isointense, T2 iso to hyperintense, variable contrast enhancement
What is the ‘dropped jaw syndrome’ associated with?
Idiopathic trigeminal neuropathy
What are the MRI features of trigeminal nerve sheath tumors?
Extra-axial mass on the ventral aspect of the cranial vault, hyperintensity on T1 and T2 of masticatory muscles
What is the function of the tensor veli palatini muscle?
Innervated by a branch of the mandibular nerve
What do cavernous sinuses provide for the orbit and brain?
Venous drainage
What are the MRI features of facial nerve paralysis secondary to otitis media/interna?
Abnormal enhancement of the intratemporal facial nerve, absence of middle/inner ear pathology
What MRI findings are associated with vestibulocochlear nerve diseases?
T2 hyperintense/T1 isointense material filling the tympanic bulla, post-contrast enhancement of the lining of the affected bulla
