Cranial nerve nucleus
Encyclopedia
A cranial nerve nucleus is a collection of neuron
s (gray matter
) in the brain stem
that is associated with one or more cranial nerves
. Axon
s 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.
tends to be efferent (motor) fibers, and the dorsal horn tends to contain afferent (sensory) neuron
s, nuclei in the brainstem are arranged in an analogous way.
medulla oblongata
pons
Neuron
A neuron is an electrically excitable cell that processes and transmits information by electrical and chemical signaling. Chemical signaling occurs via synapses, specialized connections with other cells. Neurons connect to each other to form networks. Neurons are the core components of the nervous...
s (gray matter
Gray Matter
"Gray Matter" is a short story by Stephen King, first published in the October 1973 issue of Cavalier magazine, and later collected in King's 1978 collection Night Shift. It is set in the same area as King's novel Dreamcatcher.-Setting:...
) in the brain stem
Brain stem
In vertebrate anatomy the brainstem is the posterior part of the brain, adjoining and structurally continuous with the spinal cord. The brain stem provides the main motor and sensory innervation to the face and neck via the cranial nerves...
that is associated with one or more cranial nerves
Cranial nerves
Cranial nerves are nerves that emerge directly from the brain, in contrast to spinal nerves, which emerge from segments of the spinal cord. In humans, there are traditionally twelve pairs of cranial nerves...
. Axon
Axon
An axon is a long, slender projection of a nerve cell, or neuron, that conducts electrical impulses away from the neuron's cell body or soma....
s carrying information to and from the cranial nerves form a synapse
Synapse
In the nervous system, a synapse is a structure that permits a neuron to pass an electrical or chemical signal to another cell...
first at these nuclei
Nucleus (neuroanatomy)
In neuroanatomy, a nucleus is a brain structure consisting of a relatively compact cluster of neurons. It is one of the two most common forms of nerve cell organization, the other being layered structures such as the cerebral cortex or cerebellar cortex. In anatomical sections, a nucleus shows up...
. 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.
Arrangement of the nuclei
Just as grey matter in the ventral (closer to front of a human) spinal cordSpinal cord
The spinal cord is a long, thin, tubular bundle of nervous tissue and support cells that extends from the brain . The brain and spinal cord together make up the central nervous system...
tends to be efferent (motor) fibers, and the dorsal horn tends to contain afferent (sensory) neuron
Neuron
A neuron is an electrically excitable cell that processes and transmits information by electrical and chemical signaling. Chemical signaling occurs via synapses, specialized connections with other cells. Neurons connect to each other to form networks. Neurons are the core components of the nervous...
s, nuclei in the brainstem are arranged in an analogous way.
- Close to the midline are the motor efferent nuclei, such as the oculomotor nucleusOculomotor nucleusThe fibers of the oculomotor nerve arise from a nucleus in the midbrain, which lies in the gray substance of the floor of the cerebral aqueduct and extends in front of the aqueduct for a short distance into the floor of the third ventricle...
, which control skeletal muscle. Just lateral to this are the autonomic (or visceral) efferent nuclei.
- There is a separation, called the sulcus limitansSulcus limitansIn the floor of the fourth ventricle, the sulcus limitans separates the cranial nerve motor nuclei from the sensory nuclei . In the superior part of the rhomboid fossa, it corresponds with the lateral limit of the fossa and presents a bluish-gray area, the locus ceruleus In the floor of the fourth...
, and lateral to this are the sensory nuclei. Near the sulcus limitans are the visceral afferentVisceral afferentVisceral afferent can refer to:* General visceral afferent fibers* Special 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 afferentSpecial somatic afferentSpecial somatic afferent refers to afferent nerves that carry information from the special senses of vision, hearing and balance. The cranial nerves containing SSA fibers are the optic nerve and the vestibulocochlear nerve...
s, 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 archBranchial archIn the development of vertebrate animals, the pharyngeal arches are anlage for a multitude of structures. In humans, they develop during the fourth week in utero as a series of mesodermal outpouchings on the left and right sides of the developing pharynx...
es, in the embryo. This area is a bit below the autonomic motor nuclei, and includes the nucleus ambiguusNucleus ambiguusThe nucleus ambiguus is a region of histologically disparate cells located just dorsal to the inferior olivary nucleus in the lateral portion of the upper medulla...
, facial nerveFacial nerveThe facial nerve is the seventh of twelve paired cranial nerves. It emerges from the brainstem between the pons and the medulla, and controls the muscles of facial expression, and functions in the conveyance of taste sensations from the anterior two-thirds of the tongue and oral cavity...
nucleus, as well as the motor part of the trigeminal nerveTrigeminal nerveThe trigeminal nerve contains both sensory and motor fibres. It is responsible for sensation in the face and certain motor functions such as biting, chewing, and swallowing. Sensory information from the face and body is processed by parallel pathways in the central nervous system...
nucleus.
Examples of nuclei
There are several cranial nerve nuclei (roman numeral refers to the cranial nerve number):medulla oblongataMedulla oblongataThe medulla oblongata is the lower half of the brainstem. In discussions of neurology and similar contexts where no ambiguity will result, it is often referred to as simply the medulla...
- Hypoglossal nucleusHypoglossal nucleusThe hypoglossal nucleus is a cranial nerve nucleus, and it extends the length of the medulla, and being a motor nucleus, is close to the midline...
(XII) - motor - Dorsal motor nucleus of vagus nerve (X) - visceromotor
- Nucleus ambiguusNucleus ambiguusThe nucleus ambiguus is a region of histologically disparate cells located just dorsal to the inferior olivary nucleus in the lateral portion of the upper medulla...
(IX, X, XI) - motor - Solitary nucleusSolitary nucleusThe solitary tract and nucleus are structures in the brainstem that carry and receive visceral sensation and taste from the facial , glossopharyngeal and vagus cranial nerves.-Anatomy:...
(VII, IX, X) - sensory - Spinal trigeminal nucleusSpinal trigeminal nucleusThe spinal trigeminal nucleus is a nucleus in the medulla that receives information about deep/crude touch, pain, and temperature from the ipsilateral face. The facial, glossopharyngeal, and vagus nerves also convey pain information from their areas to the spinal trigeminal nucleus.This nucleus...
(V) - sensory (crude touch, temperature and pain) - Inferior olivary nucleusInferior olivary nucleusThe inferior olivary nucleus is the largest nucleus situated in the olivary body, part of the medulla oblongata.-Function:It is closely associated with the cerebellum, meaning that it is involved in control and coordination of movements, sensory processing and cognitive tasks likely by encoding the...
afferent fibres to cerebellum
ponsPonsThe pons is a structure located on the brain stem, named after the Latin word for "bridge" or the 16th-century Italian anatomist and surgeon Costanzo Varolio . It is superior to the medulla oblongata, inferior to the midbrain, and ventral to the cerebellum. In humans and other bipeds this means it...
- Cochlear nucleiCochlear nucleiThe cochlear nuclei are two heterogeneous collections of neurons in the mammalian brainstem that receive input from the cochlear nerve, which carry sound information from the cochleae...
(VIII) - sensory- Dorsal cochlear nucleusDorsal cochlear nucleusThe dorsal cochlear nucleus , is a cortex-like structure on the dorso-lateral surface of the brainstem...
- Ventral cochlear nucleus
- Dorsal cochlear nucleus
- Vestibular nucleiVestibular nucleiThe vestibular nuclei are the cranial nuclei for the vestibular nerve.In Terminologia Anatomica they are grouped in both the pons and medulla.-Subnuclei:There are 4 subnuclei; they are situated at the floor of the fourth ventricle....
(VIII) - sensory - Salivary nucleiSalivary nucleiSalivary nuclei may refer to:* Inferior salivatory nucleus, one of the components of the glossopharyngeal nerve* Superior salivary nucleus of the facial nerve, a visceromotor cranial nerve nucleus located in the pontine tegmentum...
- visceromotor- Inferior salivary nucleus (IX)
- Superior salivary nucleusSuperior salivary nucleusThe Superior salivary nucleus of the facial nerve is a visceromotor cranial nerve nucleus located in the pontine tegmentum....
(VII)
- Facial nucleus (VII) - motor
- Abducens nucleusAbducens nucleusThe abducens nucleus is the originating nucleus from which the abducens nerve emerges - a cranial nerve nucleus. This nucleus is located beneath the fourth ventricle in the caudal portion of the pons, medial to the sulcus limitans....
(VI) - motor - Trigeminal motor nucleusTrigeminal motor nucleusThe trigeminal motor nucleus contains motor neurons that innervate muscles of the first branchial arch, namely the muscles of mastication, the tensor tympani, tensor veli palatini, mylohyoid, and anterior belly of the digastric.-External links:*...
(V) - motor - Main trigeminal nucleus (V) - sensory (fine touch and vibration)
midbrain (mesencephalon)
- Mesencephalic trigeminal nucleus (V) - sensory
- Red nucleusRed nucleusThe red nucleus is a structure in the rostral midbrain involved in motor coordination. It comprises a caudal magnocellular and a rostral parvocellular part.-Function:...
- motor, extrapyramidal - Trochlear nucleusTrochlear nucleusThe nucleus of the trochlear nerve is located in the midbrain, at the level of the inferior colliculus. It is a motor nucleus, so is located near the midline....
(IV) - motor - Oculomotor nucleusOculomotor nucleusThe fibers of the oculomotor nerve arise from a nucleus in the midbrain, which lies in the gray substance of the floor of the cerebral aqueduct and extends in front of the aqueduct for a short distance into the floor of the third ventricle...
(III) - motor - Edinger-Westphal nucleusEdinger-Westphal nucleusThe Edinger-Westphal nucleus is the accessory parasympathetic cranial nerve nucleus of the oculomotor nerve , supplying the constricting muscles of the iris...
(III) - visceromotor