nucleus (redirected from Nucelar)

nucleus /nu·cle·us/ (noo´kle-us) pl. nu´clei   [L.]

1. the central core of a body or object.

2. cell nucleus; a spheroid body within a cell, consisting of a thin nuclear membrane, organelles, one or more nucleoli, chromatin, linin, and nucleoplasm.

3. a group of nerve cells, usually within the central nervous system, bearing a direct relationship to the fibers of a particular nerve.

4. 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.

5. see atomic n. nu´clear

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ambiguous nucleus  the nucleus of origin of motor fibers of the vagus, glossopharyngeal, and accessory nerves in the medulla oblongata.

anterior olfactory nucleus  scattered groups of neurons intermingled with the olfactory tract that run caudally from the end of the olfactory bulb, some receiving synaptic stimuli from the fibers of the olfactory tract.

arcuate nucleus 

1. a nucleus of nerve cells in the posterior hypothalamic region, extending into the median eminence and almost entirely surrounding the base of the infundibulum.

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

atomic nucleus  the central core of an atom, composed of protons and neutrons, constituting most of its mass but only a small part of its volume.

basal nucleus , nucleus basa´lis specific interconnected groups of masses of gray substance deep in the cerebral hemispheres and in the upper brain stem.

nucleus caeru´leus  a compact aggregation of pigmented neurons subjacent to the locus caeruleus, sometimes considered one of the medial reticular nuclei.

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

Nucleus caudatus (caudate nucleus) in a lateral view of the left side of the brain.

central nuclei of thalamus  two small intralaminar nuclei, medial and lateral, situated in the internal medullary lamina.

centromedian nucleus of thalamus  the largest and most caudal of the intralaminar nuclei of the dorsal thalamus.

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

cuneate nucleus , nucleus cunea´tus a nucleus in the medulla oblongata, in which the fibers of the fasciculus cuneatus synapse.

Deiters' nucleus  lateral vestibular nucleus; see nuclei vestibulares.

dentate nucleus , nucleus denta´tus the largest of the deep cerebellar nuclei lying in the white matter of the cerebellum.

droplet nuclei  see under infection.

emboliform nucleus , nucleus embolifor´mis a small cerebellar nucleus that lies between the dentate nucleus and globose nucleus and contributes to the superior cerebellar peduncles.

nucleus endopeduncula´ris  a small nucleus in the internal capsule of the hypothalamus, adjacent to the medial edge of the globus pallidus.

fastigial nucleus , nucleus fastigia´tus, nucleus fasti´gii the most medial of the deep cerebellar nuclei, near the midline in the roof of the fourth ventricle.

nucleus gra´cilis  a nucleus in the medulla oblongata, in which the fibers of the fasciculus gracilis of the spinal cord synapse.

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

interpeduncular nucleus , nucleus interpeduncula´ris a nucleus between the cerebral peduncles immediately dorsal to the interpeduncular fossa.

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

Meynert's nucleus  a group of neurons in the basal forebrain that has wide projections to the neocortex and is rich in acetylcholine and choline acetyltransferase; it undergoes degeneration in paralysis agitans and Alzheimer's disease.

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

oculomotor nucleus , nucleus oculomoto´rius the origin of the fibers of the oculomotor nerve, situated in the tegmentum of the mesencephalon immediately ventral to the central gray matter, between the medial longitudinal fasciculi. Innervation of the superior rectus of one eye originates in the contralateral oculomotor nerve nucleus; the other elements of the nucleus supply ipsilateral eye muscles via the oculomotor nerve.

olivary nucleus 

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

2. olive (2).

nucleus of origin  any of the groups of nerve cells in the central nervous system from which arise the motor, or efferent, fibers of the cranial nerves.

paraventricular nucleus of hypothalamus  a band of cells in the wall of the third ventricle in the anterior hypothalamic region; many of its cells are neurosecretory in function (secreting oxytocin) and project to the neurohypophysis.

pontine nuclei , nu´clei pon´tis 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.

nucleus pulpo´sus , pulpy nucleus a semifluid mass of fine white and elastic fibers forming the center of an intervertebral disk.

raphe nuclei , nuclei of raphe a subgroup of the reticular nuclei of the brainstem, found in narrow longitudinal sheets along the raphae of the medulla oblongata, pons, and mesencephalon; they include many neurons that synthesize serotonin.

red nucleus  a distinctive oval nucleus (pink in fresh specimens) centrally placed in the upper mesencephalic reticular formation.

reticular nuclei  nuclei found in the reticular formation of the brainstem, occurring primarily in longitudinal columns in three groups: medial or intermediate reticular nuclei, lateral reticular nuclei, and reticular nuclei of the raphe.

nucleus ru´ber  red n.

salivary nuclei  two columns of cells in the posterolateral part of the reticular formation of the pons, together comprising the parasympathetic outflow for the supply of the salivary glands.

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

solitary nuclei  any of various nuclei of termination of the visceral afferent fibers of the facial, glossopharyngeal, and vagus nerves, which enter the solitary tract.

subthalamic nucleus , nucleus subthala´micus a nucleus on the medial side of the junction of the internal capsule and crus cerebri.

supraoptic nucleus  one just above the lateral part of the optic chiasm; many of its cells are neurosecretory in function (secreting antidiuretic hormone) and project to the neurohypophysis; other cells are osmoreceptors which respond to increased osmotic pressure to signal the release of antidiuretic hormone by the neurohypophysis.

tegmental nucleus, laterodorsal  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.

terminal nucleus  groups of nerve cells within the central nervous system on which the axons of primary afferent neurons of various cranial nerves synapse.

thoracic nucleus  see under column.

nuclei of trapezoid body  two groups of nerve cell bodies in or next to the trapezoid body.

trigeminal nuclei  four nuclei located along the trigeminal nerve, chiefly in the pons and medulla oblongata.

nu´clei vestibula´res  the four (superior, lateral, medial, and inferior) cellular masses in the floor of the fourth ventricle in which the branches of the vestibulocochlear nerve terminate.

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nu·cle·us (nkl-s)

n. pl. nu·cle·us·es or nu·cle·i (-kl-)

1. A large, membrane-bound, usually spherical protoplasmic structure within a living cell, containing the cell's hereditary material and controlling its metabolism, growth, and reproduction. Also called karyon.

2. A membraneless structure in microorganisms that contains genetic material but does not itself replicate. Also called nucleoid.

3. A group of specialized nerve cells or a localized mass of gray matter in the brain or spinal cord.

4. The substance around which a urinary or other calculus forms.

5. The positively charged central region of an atom that is composed of protons and neutrons and that contains almost all of the mass of the atom.

6. A group of atoms bound in a structure, such as a benzene ring, that is resistant to alteration in chemical reactions.

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Nucleus

The central part of a cell that contains most of its genetic material, including chromosomes and DNA.

Mentioned in: Gene Therapy

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nucleus

[n(y)o̅o̅′klē·əs] pl. nuclei

Etymology: L, nut kernel

1 the central controlling body within a living cell, usually a spheric unit enclosed in a membrane and containing genetic codes for maintaining life systems of the organism and for issuing commands for growth and reproduction.

2 a group of nerve cells of the central nervous system having a common function, such as supporting the sense of hearing or smell.

3 the center of an atom about which electrons rotate.

4 the central element in an organic chemical compound or class of compounds. Formerly called cytoblast. -nuclear, adj.

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nucleus,

n 1. in chemistry, a small, closely packed, centrally located body within an atom comprised of positively charged protons and neutral particles called neutrons. The bulk of the mass of an atom is contained within the nucleus.
2. in biology, a small, closely packed, centrally located organelle within a cell that contains the genetic material.

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nucleus (noo´klēus),

n 1. the small, central part of an atom in which the positive electric charge and most of the mass (protons and neutrons) are concentrated.
n 2. an easily recognized structural component of most cells, surrounded by a membrane and containing chromosomes and nucleolus.

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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.

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nucleus

1. A mass of grey matter composed of nerve cell bodies in any part of the brain or spinal cord and dealing with a common function. 2. Core or central portion of the cell body of a neuron, containing cellular DNA in particular. Plural: nuclei.
abducens nucleus Nucleus of the abducens nerve (sixth cranial nerve) located in the lower part of the pons and whose axons supply the lateral rectus muscle.
accessory oculomotor nucleus See Edinger-Westphal nucleus.
nucleus of the crystalline lens See crystalline lens.
Edinger-Westphal nucleus Part of the oculomotor nucleus, it is situated posterior to the main nucleus and contains the parasympathetic component of the complex. Axons from the Edinger-Westphal pass out along the third (or oculomotor) nerve to synapse in the ciliary ganglion. Postganglionic fibres pass through the short ciliary nerves to the sphincter pupillae and ciliary muscles. The nucleus also receives fibres concerned with accommodation and fibres from the pretectal nucleus dealing with pupil light reflexes. Syn. accessory oculomotor nucleus; accessory parasympathetic nucleus. See pretectal nucleus; pupil light reflex.
lateral nucleus Part of the oculomotor nucleus which supplies, via the oculomotor nerve, all the extraocular muscles except the superior oblique and the lateral rectus muscles.
lateral geniculate nucleus See lateral geniculate body.
oculomotor nucleus This is the nucleus of the oculomotor nerve (third cranial nerve). It is a complex mass of cells located in the midbrain at the level of the superior colliculus and beneath the cerebral aqueduct (of Sylvius) which connects the third and fourth ventricles. It is divided into several subnuclei. See oculomotor nerve; Edinger-Westphal nucleus; Perlia's nucleus; trochlear nucleus.
olivary nucleus See pretectum; pupil light reflex.
Perlia's nucleus Midline part of the oculomotor nucleus. It is rudimentary in man and primates and may provide part of the innervation of the superior rectus muscle.
pretectal nucleus A complex group of nerve cells in the midbrain anterior to the superior colliculi. One of these, the pretectal olivary nucleus, receives retinal inputs via the optic tract and superior brachium and sends axons to both Edinger-Westphal nuclei. It constitutes a centre of the pupil light reflex. Another, the nucleus of the optic tract, may be involved in the control of reflex eye movements. Other fibres from the pretectal nucleus innervate the cornea, the iris, the ciliary muscle and the extraocular muscles (except the lateral rectus and superior oblique muscles), as well as the levator palpebrae muscle.
trochlear nucleus A nucleus of the trochlear nerve (fourth cranial nerve) located at the level of the inferior colliculus and below the posterior end of the oculomotor nerve nucleus, it sends fibres to the contralateral superior oblique muscle.