The cranial nerves are those nerves that attach to the brain. They are paired and are numbered (typically by Roman numerals) from anterior to posterior. The olfactory nerve is a sensory nerve that receives the sense of smell from the nose and transmits it to the brain. The optic nerve takes visual impulses from the eye while the oculomotor nerve mostly takes motor impulses to several muscles that move the eye. The trochlear nerve takes motor impulses to the superior oblique muscle. The trochlear nerve is so named because it innervates a muscle that passes through a loop called the trochlea. The trigeminal nerve is a large nerve located laterally in the pons. It is a mixed nerve (having both sensory and motor functions) that has three branches. The ophthalmic branch innervates the upper head while the maxillary branch innervates the region around the maxilla. The mandibular branch innervates the jaw. The abducens nerve is posterior to the trigeminal and is located exiting the brain between the pons and the medulla oblongata. It is a motor nerve to the lateral rectus muscle of the eye. On the anterior portion of the medulla oblongata is the facial nerve, which is both a sensory and motor nerve to the face and the tongue. The vestibulocochlear nerve is a sensory nerve that receives impulses from the ear. It picks up auditory stimuli as well as information about equilibrium. The glossopharyngeal nerve is a nerve that carries both sensory and motor impulses. It innervates the tongue and throat. A large nerve on the side of the medulla oblongata is the vagus nerve. It is also a mixed nerve carrying both sensory and motor impulses. The vagus nerve innervates organs in the thoracic and abdominal regions. The accessory nerve is inferior to the vagus nerve and is a motor nerve to the neck muscles. The hypoglossal nerve is a motor nerve to the tongue. Label the cranial nerves and color each pair a different color.
Answer Key: a. Olfactory, b. Optic, c. Oculomotor, d. Trochlear, e. Trigeminal, f. Abducens, g. Facial, h. Vestibulocochlear, i. Glossopharyngeal, j. Vagus, k. Accessory, I. Hypoglossal
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This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.