Cranial Nerves and Pathways
Preview this topic section
Each condition includes a free overview and clinical definition. Plans unlock the full Step 1 details.
Cranial Nerves and Pathways conditions
Bell PalsyBell Palsy causes sudden unilateral facial paralysis due to inflammation of the facial nerve, often linked to herpes simplex virus reactivation.Cavernous Sinus SyndromeA syndrome caused by lesions in the cavernous sinus leading to ophthalmoplegia, sensory loss in V1/V2 distribution, and Horner syndrome due to sympathetic fiber involvement.CN III PalsyOculomotor nerve palsy (CN III palsy) causes ptosis, eye movement limitation, and pupil involvement due to nerve compression or ischemia, critical for neuroanatomy.CN IV PalsyCN IV palsy causes vertical diplopia due to trochlear nerve dysfunction, often presenting with head tilt to compensate for superior oblique muscle weakness.CN V Motor LesionCN V Motor Lesion involves damage to the motor fibers of the trigeminal nerve causing weakness in mastication muscles, jaw deviation, and decreased jaw reflex.CN VI PalsyCN VI palsy causes lateral rectus muscle weakness leading to horizontal diplopia and impaired eye abduction, often linked to increased intracranial pressure.CN X LesionCN X lesion involves damage to the vagus nerve causing hoarseness, dysphagia, loss of gag reflex, and impaired parasympathetic control of thoracic and abdominal organs.CN XI LesionCN XI lesion involves damage to the accessory nerve causing weakness in the sternocleidomastoid and trapezius muscles, leading to shoulder droop and impaired head rotation.CN XII LesionCN XII lesion involves damage to the hypoglossal nerve causing tongue weakness, atrophy, and deviation toward the affected side during protrusion.Ramsay Hunt SyndromeRamsay Hunt Syndrome is caused by varicella-zoster virus reactivation affecting the facial nerve, leading to facial paralysis and painful ear rash.