tegmental nucleus

tegmental nucleus

n.

Either of two small round cell groups in the caudal part of the midbrain, associated with the mamillary body via the mamillary peduncle and mamillotegmental tract.

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nucleus

pl. nuclei [L.]

1. cell nucleus; a spheroid body within a cell, contained in a double membrane, the nuclear envelope, and containing the chromosomes and one or more nucleoli. The contents are collectively referred to as nucleoplasm. The chromosomes contain deoxyribonucleic acid (DNA), which is the genetic material that codes for the structure of all the proteins of the cell.

2. a mass of gray matter in the central nervous system, especially such a mass marking the central termination of a cranial nerve.

3. in organic chemistry, the combination of atoms forming the central element or basic framework of the molecule of a specific compound or class of compounds.

4. the dense core of an atom; called also atomic nucleus. It is made of protons and neutrons held together by the strong nuclear force. Traveling in orbit around the nucleus is a cloud of negatively charged particles called electrons. The number of protons in the atomic nucleus gives a substance its identity as a particular element (2).

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nucleus abducens

located in the floor of the fourth ventricle; its axons constitute the abducent nerve.

nucleus ambiguus

the nucleus of origin of motor fibers of the glossopharyngeal, vagus and accessory nerves that supply the striated muscle of the pharynx and larynx. Found in the medulla oblongata.

arcuate nucleus, nucleus arcuati

small irregular areas of gray substance on the ventromedial aspect of the pyramid of the medulla oblongata.

atomic nucleus

nucleus (3).

basal nucleus

large brain nuclei, the caudate and lentiform nuclei, which combine with the white matter to form the corpus striatum. Important in the regulation of motor function.

caudate nucleus, nucleus caudatus

an elongated, arched gray mass closely related to the lateral ventricle throughout its entire extent, which, together with the putamen, forms the neostriatum.

central nervous system nucleus

aggregations of neurons within the brain.

cerebellar nucleus

there are a number of them; they are surrounded by the medulla oblongata caudal to the cerebellum.

cochlear nucleus (dorsal and ventral)

the nuclei of termination of sensory fibers of the cochlear part of the vestibulocochlear (eighth cranial) nerve, which partly encircle the inferior cerebellar peduncle at the junction of the medulla oblongata and pons.

cranial nerve nucleus

aggregations of cell bodies associated with the cranial nerves, which in general are organized as continuations of the four gray matter components of the spinal cord plus three others which appear in the medulla oblongata developed for innervation of the organs in the head.

cuneate nucleus

medial and lateral nuclei are situated in the medulla oblongata.

dentate nucleus, nucleus dentatus

the largest of the deep cerebellar nuclei lying in the white matter of the cerebellum.

Edinger-Westphal nucleus

located in the midbrain and a center for coordination of oculomotor activity.

facial nucleus

in the medulla oblongata and the origin of the facial nerve.

gracile nucleus

located in the medulla oblongata.

habenular nucleus

the gray matter of the habenula.

hypoglossal nucleus

located in the medulla oblongata, the origin of the hypoglossal nerve.

lateral geniculate nucleus

concerned in the transmission of visual stimuli.

lenticular nucleus, lentiform nucleus

the part of the corpus striatum just lateral to the internal capsule, comprising the putamen and globus pallidus.

medial geniculate nucleus

a nucleus within the thalamus; involved in transmission of auditory stimuli.

motor nucleus

any collection of cells in the central nervous system giving origin to a motor nerve.

oculomotor nucleus

the cells of the midbrain which make up the origin of the oculomotor nerve.

olivary nucleus, nucleus olivaris

1. a folded band of gray matter enclosing a white core and producing the elevation (olive) on the medulla oblongata.

2. olive (2).

nucleus of origin

any collection of nerve cells giving origin to the fibers, or a part of the fibers, of a peripheral nerve.

paraventricular nucleus, nucleus paraventricularis

a band of cells in the wall of the third ventricle in the supraoptic part of the hypothalamus; many of its cells are neurosecretory in function and project to the neurohypophysis, where they secrete oxytocin (and, to a lesser extent, antidiuretic hormone).

pontine nucleus, nucleus pontis

groups of nerve cell bodies in the part of the pyramidal tract within the ventral part of the pons, upon which the fibers of the corticopontine tract synapse, and whose axons in turn cross to the opposite side and form the middle cerebellar peduncle.

pulpy nucleus, nucleus pulposus

a semifluid mass of fine white and elastic fibers forming the center of an intervertebral disk. It serves to distribute pressure over the vertebral body. It shows early age changes, may calcify and herniate through the fibrous rings that enclose it to cause disk disease.

red nucleus

an oval mass of gray matter (pink in fresh specimens) in the anterior part of the tegmentum and extending into the posterior part of the hypothalamus; one of the important relay stations in the extrapyramidal motor pathway of the CNS; origin of the rubrospinal tract in the cord; called also nucleus ruber.

nucleus ruber

see red nucleus (above).

salivatory nucleus

groups of preganglionic parasympathetic neurons concerned with salivary secretion organized into a rostral nucleus, of the facial nerve, and the caudal nucleus, of the glossopharyngeal nerve.

sensory nucleus

the nucleus of termination of the afferent (sensory) fibers of a peripheral nerve.

supraoptic nucleus, nucleus supraopticus

one just above the lateral part of the optic chiasm; many of its cells are neurosecretory in function and project to the neurohypophysis, where they secrete antidiuretic hormone (ADH) and, to a lesser extent, oxytocin; other cells are osmoreceptors that stimulate ADH release in response to increased osmotic pressure.

tegmental nucleus

several nuclear masses of the reticular formations of the pons and midbrain, especially of the latter, where they are in close approximation to the superior cerebellar peduncles.

thoracic nucleus, nucleus thoracicus

a column of cells in the dorsal gray column of the spinal cord, extending from the seventh or eighth cervical segments to the second or third lumbar level.

trapezoid body nucleus

a relay station in the auditory pathways.

trigeminal nucleus

there are three sensory nuclei and one motor nucleus of the trigeminal nerve found in the brainstem; the sensory nuclei comprise the mesencephalic nucleus, the nucleus of the descending tract, and the principal sensory nucleus, but none is exclusive to the trigeminal nerve, all of them receiving sensory inputs from other cranial nerves.

trochlear nucleus

source of the trochlear nerve; located in the tegmentum of the midbrain.

vagus nucleus

source of the vagus nerve.

vestibular nucleus, nucleus vestibularis

the four cellular masses (superior, lateral, medial and inferior) in the floor of the fourth ventricle, in which the branches of the eighth cranial (vestibulocochlear) nerve terminate.