Cranial nerve nucleus
Brain: Cranial nerve nucleus
Gray696.png
The cranial nerve nuclei schematically represented; dorsal view. Motor nuclei in red; sensory in blue. (The olfactory and optic centers are not represented.)
Latin nucleus nervi cranialis
Gray's subject #195 881

A cranial nerve nucleus is a collection of neurons (gray matter) in the brain stem that is associated with one or more cranial nerves. Axons carrying information to and from the cranial nerves form a synapse first at these nuclei. Lesions occurring at these nuclei can lead to effects resembling those seen by the severing of nerve(s) they are associated with. All the nuclei excepting that of the IV nerve supply nerves of the same side of the body.

Contents

Arrangement of the nuclei

Just as grey matter in the ventral (closer to front of a human) spinal cord tends to be efferent (motor) fibers, and the dorsal horn tends to contain afferent (sensory) neurons, nuclei in the brainstem are arranged in an analogous way.

  • Close to the midline are the motor efferent nuclei, such as the oculomotor nucleus, which control skeletal muscle. Just lateral to this are the autonomic (or visceral) efferent nuclei.
  • There is a separation, called the sulcus limitans, and lateral to this are the sensory nuclei. Near the sulcus limitans are the visceral afferent nuclei, namely the solitary tract nucleus.
  • More lateral, but also less posterior, are the general somatic afferent nuclei. This is the trigeminal nucleus. Back at the dorsal surface of the brainstem, and more lateral are the special somatic afferents, this handles sensation such as balance.
  • Another area, not on the dorsum of the brainstem, is where the branchial efferent nuclei reside. These formed from the branchial arches, in the embryo. This area is a bit below the autonomic motor nuclei, and includes the nucleus ambiguus, facial nerve nucleus, as well as the motor part of the trigeminal nerve nucleus.

Examples of nuclei

There are several cranial nerve nuclei (roman numeral refers to the cranial nerve number):

hindbrain (rhombencephalon)

medulla oblongata

Micrograph of the posterior portion of the open part of the medulla oblongata, showing the fourth ventricle (top of image) and the hypoglossal nucleus (medial - left of image) and the dorsal motor nucleus of the vagus nerve (lateral - right of image). H&E-LFB stain.

pons

midbrain (mesencephalon)


References

Additional images

External links


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