Lectures 8, 10: Brainstem and Cranial Nerves Flashcards
The trochlear nerve emerges __________ and wraps around the brainstem at what junction?
Ventrally; at the junction b/t the midbrain and pons
Motor nuclei are _______ and sensory nuclei are _______
Medial; lateral
Cortical innervation of cranial nerves is bilateral in all cases except (2)
Portion of VII and XII
What is the significance of bilateral cortical innervation of cranial nerves?
Unilateral cortical lesion would not impact nerve function
What is the sole CN that crosses the midline?
IV
Discuss the anatomy of the olfactory nerve
Short primary sensory nerves (cranial nerves) –> (cribiform plate) –> Olfactory bulb –> primary olfactory cortex
What is one way to damage olfactory nerve fibers? What process of the cell is damaged?
Anterior cranial fossa fractures; primary axons
How do you test for CSF rinorrhea?
Glucose or beta 2 transferrin
Anosmia
Loss of sense of smell
Parosmia
Perverted sense of smell
Olfactory hallucinations are often caused by…
Temporal lobe (parahippocampal) seizures
How do you test olfactory nerve function?
Coffee/vanilla, one side at a tie; note: don’t use an irritating smell
Temporary anosmia caused by colds affects what level of the olfactory system?
The receptors
What are four ways to damage the central processing structures of the olfactory system?
Contusion/laceration of olfactory bulb, aneurysm, olfactory groove meningioma, frontal lobe tumor
What are the 3 trigeminal sensory nuclei and what do each control?
- Spinal trigeminal: crude touch; 2. Pontine Trigeminal (chief): discriminative touch; 3. Mesencephalic: proprioception from muscles of mastication
Where is the trigeminal motor nucleus?
The pons
What are the 3 branches of the trigeminal nerve and where does each exit the skull?
V1: Opthalmic, superior orbital fissure; V2: Maxillary, foramen rotundum; V3: Mandibular, foramen ovale
Where are the cell bodies of the sensory fibers of the trigeminal nerve?
Trigeminal ganglion