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# Nervous System: Description of Instruments The document describes several cranial nerves. **IV. Trochlear Nerves:** * **OR (Origin):** Trochlear nucleus in midbrain * **OA (Course):** Posterior surface of the brainstem (TC). The nerve structure is innervated by muscles of the superior oblique...

# Nervous System: Description of Instruments The document describes several cranial nerves. **IV. Trochlear Nerves:** * **OR (Origin):** Trochlear nucleus in midbrain * **OA (Course):** Posterior surface of the brainstem (TC). The nerve structure is innervated by muscles of the superior oblique of the eyeball. * **Function:** Motor nerves **V. Trigeminal Nerves:** * **Types of Fibers:** Mixed; three main branches (ophthalmic, maxillary, mandibular) * **Sensory Fibers (OR):** Primary sensory neurons (N1) in the trigeminal ganglion on the anterior surface of the temporal bone. Axons of these neurons send signals to the trigeminal nuclei (N2) in the midbrain, pons, and medulla. * **Motor Fibers (OR):** Motor nuclei in the pons. * **Sensory Fibers (OA):** Located on the anterior surface of the pons, with motor fibers positioned more laterally. * **Function:** Sensory information from the face and motor commands to masticatory muscles. **VI. Abducens Nerves:** * **OR (Origin):** Abducens nucleus located in the pons * **OA (Course):** Located in the bulbopontine sulcus, close to the pyramids of the medulla. Innervates the lateral rectus muscle. * **Function:** Motor nerves controlling lateral eye movement **VII. Facial Nerves:** * **Types of Fibers:** Mixed, containing both sensory and motor fibers and parasympathetic (PS) fibers. * **Sensory (OR):** Sensory fibers travel through the geniculate ganglion, synapse with secondary neurons in the nucleus solitarius of the medulla. * **Motor (OR):** Motor nuclei in the pons. * **Parasympathetic (PS):** PS fibers run through the lacrimal and superior salivatory nuclei of the pons. * **OA (Course):** Located in the bulbopontine sulcus, lateral to the abducens nerve (VI). * **Function:** Controls facial expressions, taste, and parasympathetic functions.