00:00 / 00:00
0 / 11 complete
0 / 4 complete
osteopetrosis p. 473
branchial arch derivation p. 644
common lesions p. 550
locations of p. 521
nerve and vessel pathways p. 522
nuclei of p. 523
reflexes of p. 523
cranial nerves in p. 550
cranial nerves and nuclei p. 521, 522
cranial nerve p. 523
The cranial nerves consist of 12 pairs of nerves originating directly from the brain and brainstem. They supply both motor and sensory information from the brain to other parts of the body, primarily supplying the region of the head and neck.
The nervous system is divided into the central nervous system, so the brain and the spinal cord, and the peripheral nervous system, which is further divided into the somatic and the autonomic nervous systems. Broadly speaking, the nervous system is split into an afferent and an efferent division. The afferent division brings sensory information - like vision, smell, touch, and proprioception - from the outside world into the brain. On the other hand, the efferent division brings motor information from the brain to the periphery, ultimately resulting in contraction of skeletal muscles to trigger movement through the somatic nervous system, as well as the contraction of the smooth muscles to trigger activity of the glands and organs through the autonomic nervous system.
Now, neurons are the main cells of the nervous system. And they’re composed of a cell body, which contains all of the cell’s organelles, and when there’s a group of neuron cell bodies found in the central nervous system, the whole thing is called a nucleus, while a group of neuron cell bodies that are located outside of the central nervous system is called a ganglion. Neurons also have nerve fibers that extend out from the neuron cell body - these are either dendrites that receive signals from other neurons, or axons that send signals along to other neurons. Where two neurons come together is called a synapse, and that’s where one end of an axon releases neurotransmitters, further relaying the signal to the dendrites or directly to the cell body of the next neuron in the series.
The cranial nerves are a set of 12 nerves that originate in the brain and the brainstem. They supply the muscles and skin of the head, and some of the muscles within the neck, and provide some visceral innervation in the chest and abdomen. The cranial nerves are numbered I through XII, starting with the nerve closest to the brainstem. The olfactory nerve (I) is unique in that it doesn't supply any muscles or skin; it's responsible for smell perception. The remaining 11 cranial nerves supply various muscles and skin in the head, as well as some mucous membranes and glands. Each nerve has a specific function, such as tasting food (II), controlling blinking (III), or supplying sensation to part of the face (V).
Copyright © 2023 Elsevier, its licensors, and contributors. All rights are reserved, including those for text and data mining, AI training, and similar technologies.
Cookies are used by this site.
USMLE® is a joint program of the Federation of State Medical Boards (FSMB) and the National Board of Medical Examiners (NBME). COMLEX-USA® is a registered trademark of The National Board of Osteopathic Medical Examiners, Inc. NCLEX-RN® is a registered trademark of the National Council of State Boards of Nursing, Inc. Test names and other trademarks are the property of the respective trademark holders. None of the trademark holders are endorsed by nor affiliated with Osmosis or this website.