Habenular trigone

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Habenular trigone
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Identifiers
Latin trigonum habenulae
NeuroNames 293
TA A14.1.08.005
FMA 74868
Anatomical terms of neuroanatomy

The habenular trigone is a small depressed triangular area above the superior colliculus and on the lateral aspect of the posterior part of the taenia thalami.

Superior colliculus structure in the mammalian midbrain

The superior colliculus is a structure lying on the roof of the mammalian midbrain. In non-mammalian vertebrates the homologous structure, is known as the optic tectum or optic lobe.The adjective form tectal is commonly used for both structures.

Taenia thalami a thin layer of white matter (myelinated axonal fibers) at the superior frontal surface of the thalamus

In the front, superior surface of the thalamus but separate from the inner, medial surface by a salient margin is the taenia thalami. The bottom epithelial lining of the third ventricle is in between the tela choroidea and the taenia thalami.

Underlying this area is the habenula.

Fibers enter it from the stalk of the pineal gland, and others, forming what is termed the habenular commissure, pass across the middle line to the corresponding ganglion of the opposite side.

Pineal gland small endocrine gland found in most vertebrates, which produces melatonin; in humans, located in the epithalamus, in a groove where the two halves of the thalamus join; its shape and size resembles a pine nut, after which it is named

The pineal gland, conarium, or epiphysis cerebri, is a small endocrine gland in the brain of most vertebrates. The pineal gland produces melatonin, a serotonin-derived hormone which modulates sleep patterns in both circadian and seasonal cycles. The shape of the gland resembles a pine cone from which it derived its name. The pineal gland is located in the epithalamus, near the center of the brain, between the two hemispheres, tucked in a groove where the two halves of the thalamus join. The pineal gland is one of the neuroendocrine secretory circumventricular organs in which there does not exist the blood–brain barrier at the capillary level.

Habenular commissure commissure of two habenulae, left and right

The habenular commissure, is a brain commissure situated in front of the pineal gland that connects the habenular nuclei on both sides of the diencephalon.

Most of its fibers are, however, directed downward and form a bundle, the fasciculus retroflexus of Meynert (or habenulointerpeduncular tract), which passes medial to the red nucleus, and, after decussating with the corresponding fasciculus of the opposite side, ends in the interpeduncular nucleus.

Red nucleus

The red nucleus or nucleus ruber is a structure in the rostral midbrain involved in motor coordination. The red nucleus is pale pink, which is believed to be due to the presence of iron in at least two different forms: hemoglobin and ferritin. The structure is located in the tegmentum of the midbrain next to the substantia nigra and comprises caudal magnocellular and rostral parvocellular components. The red nucleus and substantia nigra are subcortical centers of the extrapyramidal motor system.

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.

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Medulla oblongata structure of the brain stem

The medulla oblongata is a long stem-like structure which makes up part of the brainstem. It is anterior and partially inferior to the cerebellum. It is a cone-shaped neuronal mass responsible for autonomic (involuntary) functions ranging from vomiting to sneezing. The medulla contains the cardiac, respiratory, vomiting and vasomotor centers and therefore deals with the autonomic functions of breathing, heart rate and blood pressure as well as the sleep wake cycle.

Sternocleidomastoid muscle A paired muscle of the neck that traverses the neck between the manubrium sterni and the mastoid process.

The sternocleidomastoid muscle is one of the largest and most superficial cervical muscles. The primary actions of the muscle are rotation of the head to the opposite side and flexion of the neck. The sternocleidomastoid is innervated by the accessory nerve.

Spinothalamic tract

The spinothalamic tract is a sensory pathway from the skin to the thalamus. From the ventral posterolateral nucleus in the thalamus, sensory information is relayed upward to the somatosensory cortex of the postcentral gyrus.

Dorsal column–medial lemniscus pathway

The dorsal column–medial lemniscus pathway (DCML) is a sensory pathway of the central nervous system that conveys sensations of fine touch, vibration, two-point discrimination, and proprioception (position) from the skin and joints. It transmits information from the body to the primary somatosensory cortex in the postcentral gyrus of the parietal lobe of the brain. The pathway receives information from sensory receptors throughout the body, and carries this in nerve tracts in the white matter of the dorsal columns of the spinal cord, to the medulla where it is continued in the medial lemniscus, on to the thalamus and relayed from there through the internal capsule and transmitted to the somatosensory cortex. The name dorsal-column medial lemniscus comes from the two structures that carry the sensory information: the dorsal columns of the spinal cord, and the medial lemniscus in the brainstem.

Olivary body

In anatomy, the olivary bodies or simply olives are a pair of prominent oval structures in the medulla oblongata, the lower portion of the brainstem. They contain the olivary nuclei.

Spinocerebellar tract set of axonal fibers originating in the spinal cord and terminating in the ipsilateral cerebellum

The spinocerebellar tract is a nerve tract originating in the spinal cord and terminating in the same side (ipsilateral) of the cerebellum.

Palatopharyngeus muscle

The palatopharyngeusmuscle is a small muscle in the roof of the mouth.

Vestibular nuclei cranial nuclei for the vestibular nerve

The vestibular nuclei (VN) are the cranial nuclei for the vestibular nerve.

Lateral vestibular nucleus

The lateral vestibular nucleus is the continuation upward and lateralward of the principal nucleus, and in it terminate many of the ascending branches of the vestibular nerve.

Substantia innominata

The substantia innominata also innominate substance, or substantia innominata of Meynert is a series of layers in the human brain consisting partly of gray and partly of white matter, which lies below the anterior part of the thalamus and lentiform nucleus. It is included as part of the anterior perforated substance. It is part of the basal forebrain structures and includes the nucleus basalis. A portion of the substantia innominata, below the globus pallidus is considered as part of the extended amygdala.

Dorsal column nuclei

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.

Middle cerebellar peduncle

The middle cerebellar peduncles are paired structures that connect the cerebellum to the pons and are composed entirely of centripetal fibers, i.e. incoming fibers. The fibers arise from the pontine nucleus to the opposite hemisphere of the cerebellar cortex. The fibers are arranged in three fasciculi: superior, inferior, and deep.

Olivocerebellar tract

The olivocerebellar tract, also known as olivocerebellar fibers, are neural fibers which originate at the olivary nucleus and pass out through the hilum and decussate with those from the opposite olive in the raphe nucleus, then as internal arcuate fibers they pass partly through and partly around the opposite olive and enter the inferior peduncle to be distributed to the cerebellar hemisphere of the opposite side from which they arise.

Crus of diaphragm

The crus of diaphragm, refers to one of two tendinous structures that extends below the diaphragm to the vertebral column. There is a right crus and a left crus, which together form a tether for muscular contraction. They take their name from their leg-shaped appearance – crus meaning leg in Latin.

Stria medullaris of thalamus

The stria medullaris is a part of the epithalamus. It is a fiber bundle containing afferent fibers from the septal nuclei, lateral preoptico-hypothalamic region, and anterior thalamic nuclei to the habenula. It forms a horizontal ridge on the medial surface of the thalamus, and is found on the border between dorsal and medial surfaces of thalamus. Superior and lateral to habenular trigone.

Pallidothalamic tracts

The pallidothalamic tracts are a part of the basal ganglia. They provide connectivity between the internal globus pallidus (GPi) and the thalamus, primarily the ventral anterior nucleus and the ventral lateral nucleus.

Nerve tract bundle of nerve fibers (axons) connecting nuclei of the central nervous system

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, and has associated connective tissue. 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 fields of Forel are areas in a deep part of the brain known as the diencephalon. They are below the thalamus and consist of three defined, white matter areas of the subthalamus. These three regions are also named "H fields":

References

This article incorporates text in the public domain from page 812 of the 20th edition of Gray's Anatomy (1918)

The public domain consists of all the creative work to which no exclusive intellectual property rights apply. Those rights may have expired, been forfeited, expressly waived, or may be inapplicable.

<i>Grays Anatomy</i> textbook of human anatomy

Gray's Anatomy is an English written textbook of human anatomy originally written by Henry Gray and illustrated by Henry Vandyke Carter. Earlier editions were called Anatomy: Descriptive and Surgical, Anatomy of the Human Body and Gray's Anatomy: Descriptive and Applied, but the book's name is commonly shortened to, and later editions are titled, Gray's Anatomy. The book is widely regarded as an extremely influential work on the subject, and has continued to be revised and republished from its initial publication in 1858 to the present day. The latest edition of the book, the 41st, was published in September 2015.