Mammillotegmental fasciculus

Mammillotegmental fasciculus
Details
Part of	Midbrain
System	Limbic
Identifiers
Latin	fasciculus mammillotegmentalis
NeuroNames	423
TA	A14.1.08.953
FMA	62058
	Anatomical terminology [ edit on Wikidata]

Last updated April 21, 2019

The mammillotegmental fasciculus (or mammillotegmental tract, mammillo-tegmental bundle of Gudden, or Fasciculus mammillotegmentalis) is a small bundle of efferent fibers from the hypothalamus running from the mammillary body to the tegmentum.^[1] Its functions are not well defined for humans, but based on animal studies it seems to be related to regulating visceral function and processing spatial information.^[2] The mammillotegmental fasciculus was first described by the German neuroanatomist, Bernhard von Gudden, from which it takes its alternate name, mammillo-tegmental bundle of Gudden.^[3]

Mammillary body pair of small round bodies, located on the undersurface of the brain that, as part of the diencephalon, form part of the limbic system

The mammillary bodies are a pair of small round bodies, located on the undersurface of the brain that, as part of the diencephalon, form part of the limbic system. They are located at the ends of the anterior arches of the fornix. They consist of two groups of nuclei, the medial mammillary nuclei and the lateral mammillary nuclei.

The tegmentum is a general area within the brainstem. The tegmentum is the ventral part of the midbrain and the tectum is the dorsal part of the midbrain. It is located between the ventricular system and distinctive basal or ventral structures at each level. It forms the floor of the midbrain (mesencephalon) whereas the tectum forms the ceiling. It is a multisynaptic network of neurons that is involved in many subconscious homeostatic and reflexive pathways. It is a motor center that relays inhibitory signals to the thalamus and basal nuclei preventing unwanted body movement. The tegmentum area includes various different structures, such as the "rostral (=frontal/cranial/oral) end of the reticular formation, several nuclei controlling eye movements, the periaqueductal gray matter, the red nucleus, the substantia nigra, and the ventral tegmental area".

Johann Bernhard Aloys von Gudden was a German neuroanatomist and psychiatrist born in Kleve.

The mammillotegmental fasciculus emerges from the principal mammillary fasciculus of the mammillary body and travels dorsally together with the mammillothalamic tract before splitting off and turning caudally to enter the spinal column. There, it terminates in the tegmentum of the midbrain at the dorsal and ventral tegmental nuclei and the tegmental pontine reticular nucleus.^[4]

The mammillothalamic tract arises from cells in both the medial and lateral nuclei of the mammillary body and by fibers that are directly continued from the fornix.

The midbrain or mesencephalon is a portion of the central nervous system associated with vision, hearing, motor control, sleep/wake, arousal (alertness), and temperature regulation.

The ventral tegmental area (VTA), also known as the ventral tegmental area of Tsai, or simply ventral tegmentum, is a group of neurons located close to the midline on the floor of the midbrain. The VTA is the origin of the dopaminergic cell bodies of the mesocorticolimbic dopamine system and other dopamine pathways; it is widely implicated in the drug and natural reward circuitry of the brain. The VTA plays an important role in a number of processes, including cognition, motivation, orgasm, and intense emotions relating to love, as well as several psychiatric disorders. Neurons in the VTA project to numerous areas of the brain, ranging from the prefrontal cortex to the caudal brainstem and several regions in between.

Related Research Articles

The brainstem is the posterior part of the brain, continuous with the spinal cord. In the human brain the brainstem includes the midbrain, and the pons and medulla oblongata of the hindbrain. Sometimes the diencephalon, the caudal part of the forebrain, is included.

In neuroanatomy, a nucleus is a cluster of neurons in the central nervous system, located deep within the cerebral hemispheres and brainstem. The neurons in one nucleus usually have roughly similar connections and functions. Nuclei are connected to other nuclei by tracts, the bundles (fascicles) of axons extending from the cell bodies. A nucleus 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 as a region of gray matter, often bordered by white matter. The vertebrate brain contains hundreds of distinguishable nuclei, varying widely in shape and size. A nucleus may itself have a complex internal structure, with multiple types of neurons arranged in clumps (subnuclei) or layers.

The cerebral peduncles are structures at the front of the midbrain which arise from the front of the pons and contain the large ascending (sensory) and descending (motor) nerve tracts that run to and from the cerebrum from the pons. Mainly, the three common areas that give rise to the cerebral peduncles are the cerebral cortex, the spinal cord and the cerebellum. The cerebral peduncle, by most classifications, is everything in the midbrain except the tectum. The region includes the tegmentum, crus cerebri and pretectum. By this definition, the cerebral peduncles are also known as the basis pedunculi, while the large ventral bundle of efferent fibers is referred to as the cerebral crus or the pes pedunculi.

A neural pathway is the connection formed by axons that project from neurons to make synapses onto neurons in another location, to enable a signal to be sent from one region of the nervous system to another. Neurons are connected by a single axon, or by a bundle of axons known as a nerve tract, or fasciculus. Shorter neural pathways are found within grey matter in the brain, whereas longer projections, made up of myelinated axons, constitute white matter.

Reticular formation spinal trigeminal nucleus

The reticular formation is a set of interconnected nuclei that are located throughout the brainstem. The reticular formation is not anatomically well defined because it includes neurons located in different parts of the brain. The neurons of the reticular formation make up a complex set of networks in the core of the brainstem that extend from the upper part of the midbrain to the lower part of the medulla oblongata. The reticular formation includes ascending pathways to the cortex in the ascending reticular activating system (ARAS) and descending pathways to the spinal cord via the reticulospinal tracts of the descending reticular formation.

The pontine tegmentum, or dorsal pons, is located within the brainstem, and is one of two parts of the pons, the other being the ventral pons or basilar part of the pons. The pontine tegmentum can be defined in contrast to the basilar pons: basilar pons contains the corticospinal tract running craniocaudally and can be considered the rostral extension of the ventral medulla oblongata; however, basilar pons is distinguished from ventral medulla oblongata in that it contains additional transverse pontine fibres that continue laterally to become the middle cerebellar peduncle. The pontine tegmentum is all the material dorsal from the basilar pons to the fourth ventricle. Along with the dorsal surface of the medulla, it forms part of the rhomboid fossa – the floor of the fourth ventricle.

Habenula a part of the epithalamus in the diencephalon of the chordate animals brain

In neuroanatomy, habenula originally denoted the stalk of the pineal gland, but gradually came to refer to a neighboring group of nerve cells with which the pineal gland was believed to be associated, the habenular nucleus. The habenular nucleus is a set of well-conserved structures in all vertebrate animals.

The dorsal longitudinal fasciculus (DLF) is a white matter fiber tract located within the brain stem, specifically in the dorsal brainstem tegmentum. The DLF travels through the periaqueductal gray matter. The tract is composed of a diffuse brainstem pathway located in the periventricular gray matter comprising ascending visceral sensory axons and descending hypothalamic axons.

The gracile fasciculus is a nerve tract in the dorsal column-medial lemniscus pathway of the spinal cord and carries information from the lower parts of the body. The gracile fasiculus is one of many ascending tracts which carry received sensory information to the brain via the spinal cord. It is also one of the dorsal columns, the other being the cuneate fasciculus.

In neuroanatomy, the dorsal column nuclei are a pair of nuclei in the dorsal columns in the brainstem. The name refers collectively to the cuneate nucleus and gracile nucleus, which are present at the junction between the spinal cord and the medulla oblongata. Both nuclei contain second-order neurons of the dorsal column-medial lemniscus pathway, which carries fine touch and proprioceptive information from the body to the brain. Each nucleus has an associated nerve tract, the gracile fasciculus and the cuneate fasciculus.

A nerve tract is a bundle of nerve fibers (axons) connecting nuclei of the central nervous system. In the peripheral nervous system this is known as a nerve. The main nerve tracts in the central nervous system are of three types: association fibers, commissural fibers, and projection fibers. A tract may also be referred to as a commissure, fasciculus or decussation. A commissure connects the two cerebral hemispheres at the same levels. Examples are the posterior commissure and the corpus callosum. A decussation is a connection made by fibres that cross at different levels (obliquely), such as the sensory decussation. Examples of a fascicle are the subthalamic fasciculus and the lenticular fasciculus.

The midbrain reticular formation(MRF) also reticular formation of midbrain, mesencephalic reticular formation, tegmental reticular formation, formatio reticularis (tegmenti) mesencephali) is a structure in the midbrain consisting of the dorsal tegmental nucleus, ventral tegmental nucleus, and cuneiform nucleus. These are also known as the tegmental nuclei.

The Interpeduncular nucleus is an unpaired, ovoid cell group at the base of the midbrain tegmentum. It is located in the mesencephalon below the interpeduncular fossa. As the name suggests, the interpeduncular nucleus lies in between the cerebral peduncles.

The dorsal tegmental nucleus (DTN), also known as dorsal tegmental nucleus of Gudden (DTg), is a group of neurons located in the brain stem, which are involved in spatial navigation and orientation.

References

↑ Martin C. Hirsch (1999). Dictionary of Human Neuroanatomy. Springer. p. 79. ISBN 978-3540665236.
↑ Kwon, Hyeok Gyu; Hong, Ji Heon; Jang, Sung Ho (2011-05-03). "Mammillotegmental tract in the human brain: diffusion tensor tractography study". Neuroradiology. 53 (8): 623–626. doi:10.1007/s00234-011-0858-y. ISSN 0028-3940. PMID 21538047.
↑ Donkelaar, Hans J. ten (2011-06-21). Clinical Neuroanatomy: Brain Circuitry and Its Disorders (1 ed.). Springer Berlin Heidelberg.
↑ Waxman, Stephen (2013-08-02). Clinical Neuroanatomy 27/E (27 ed.). New York: McGraw-Hill Medical. ISBN 9780071797979.

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[1] Martin C. Hirsch (1999). Dictionary of Human Neuroanatomy. Springer. p. 79. ISBN 978-3540665236.

[2] Kwon, Hyeok Gyu; Hong, Ji Heon; Jang, Sung Ho (2011-05-03). "Mammillotegmental tract in the human brain: diffusion tensor tractography study". Neuroradiology. 53 (8): 623–626. doi:10.1007/s00234-011-0858-y. ISSN 0028-3940. PMID 21538047.

[3] Donkelaar, Hans J. ten (2011-06-21). Clinical Neuroanatomy: Brain Circuitry and Its Disorders (1 ed.). Springer Berlin Heidelberg.

[4] Waxman, Stephen (2013-08-02). Clinical Neuroanatomy 27/E (27 ed.). New York: McGraw-Hill Medical. ISBN 9780071797979.