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Dorsal Longitudinal Fasciculus
The dorsal longitudinal fasciculus (DLF) is a distinctive nerve tract in the midbrain. It extends from the hypothalamus rostrally to the spinal cord caudally, and contains both descending and ascending fibers. Descending fibers arise in the hypothalamus to project directly or indirectly onto autonomic nuclei and lower motor neurons of the brainstem and spinal cord; the descending component is involved in controlling chewing, swallowing, salivation and gastrointestinal secretory function, and shivering. Among the ascending fibers is a serotonin pathway arising in the raphe nuclei. Anatomy Ascending fibers Fibres arising from the nuclei of the reticular formation ascend in the DLF to terminate in the hypothalamus. It conveys visceral information to the brain. Fibers arising from the parabrachial area pass in the DLF to convey taste and general visceral sensation from the nucleus tractus solitarii to the posterior nucleus and periventricular nuclei of the hypothalamus. A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nerve Tract
A nerve tract is a bundle of nerve fibers (axons) connecting Nucleus (neuroanatomy), nuclei of the central nervous system. In the peripheral nervous system, this is known as a nerve fascicle, and has associated nervous tissue, connective tissue. The main nerve tracts in the central nervous system are of three types: association fibers, commissural fibers, and projection fibers. A nerve tract may also be referred to as a commissure, decussation, or neural pathway. A commissure connects the two cerebral hemispheres at the same levels, while a decussation connects at different levels (crosses obliquely). Types The nerve fibers in the central nervous system can be categorized into three groups on the basis of their course and connections. Different tracts may also be referred to as ''projections'' or ''radiations'' such as thalamocortical radiations. Association fibers The tracts that connect cortical areas within the same hemisphere are called Association fiber, association tr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Forebrain
In the anatomy of the brain of vertebrates, the forebrain or prosencephalon is the rostral (forward-most) portion of the brain. The forebrain controls body temperature, reproductive functions, eating, sleeping, and the display of emotions. Vesicles of the forebrain (prosencephalon), the midbrain (mesencephalon), and hindbrain (rhombencephalon) are the three primary brain vesicles during the early development of the nervous system. At the five-vesicle stage, the forebrain separates into the diencephalon (thalamus, hypothalamus, subthalamus, and epithalamus) and the telencephalon which develops into the cerebrum. The cerebrum consists of the cerebral cortex, underlying white matter, and the basal ganglia. In humans, by 5 weeks in utero it is visible as a single portion toward the front of the fetus. At 8 weeks in utero, the forebrain splits into the left and right cerebral hemispheres. When the embryonic forebrain fails to divide the brain into two lobes, it results i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Salivatory Nuclei
The salivatory nuclei are two general visceral efferent nuclei located in the caudal pons, dorsal and lateral to the facial nucleus. Their neurons give rise to preganglionic parasympathetic nerve fibers in the control of salivation.Digital version The superior salivatory nucleus supplies fibers to the intermediate nerve (part of the facial nerve (CN VII). The inferior salivatory nucleus supplies fibers to the glossopharyngeal nerve (CN IX). The nuclei may also be involved in parasympathetic control of (extracranial and intracranial) head vasculature. Superior salivatory nucleus The superior salivatory nucleus (or nucleus salivatorius superior) is a visceral motor cranial nerve nucleus of the facial nerve (CN VII). It is located in the pontine tegmentum. It projects pre-ganglionic visceral motor parasympathetic efferents (via CN VII) to the pterygopalatine ganglion, and submandibular ganglion. The term "lacrimal nucleus" is sometimes used to refer to a portion of the superio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Interpeduncular Nucleus
The interpeduncular nucleus (IPN) is an unpaired, ovoid group of neurons at the base of the midbrain tegmentum. In the midbrain it lies below the interpeduncular fossa. As the name suggests, the interpeduncular nucleus lies ''in between'' the cerebral peduncles. Composition The Interpeduncular nucleus is primarily GABAergic and contains at least two neuron clusters of different morphologies. The region is divided into 7 paired and unpaired subnuclei Subdivisions The presence of non-homologous subdivisions of the Interpeduncular nucleus was first noticed by Santiago Ramón y Cajal, Cajal over a hundred years ago. The currently recognized standard subdivision notation was mostly established by Hammill and Lenn in 1984 by combining the work and notations of four groups. Although most of their proposed convention stuck, at some point the proposed "rostral lateral" sub-nucleus was renamed "dorsomedial" and became immortalized in brain atlases. * Apical sub-nucleus (IPA) Unpaired sub-nu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fasciculus Retroflexus
The fasciculus retroflexus (FR) also known as the habenulointerpeduncular tract is a bundle of fibers located at the base of the midbrain in vertebrates. Connected to the habenula (Hbn) and the interpeduncular nucleus (IPN), the fasciculus retroflexus is involved in a variety of bodily phenomena, some being sleep retention. and drug addiction. It acts as a channel through which messages are sent between the stria medullaris and the mid- and hindbrain. The fasciculus retroflexus, along with the stria medullaris, the habenula, and the medial forebrain bundle forms a unit for the transfer of neurological impulses. In this unit, the fasciculus retroflexus mediates the transfer of information for processes such as pain, pleasure, and motor control Anatomy The fasciculus retroflexus is the main efferent track of the habenula. The FR is an extremely condensed bundle of fibers which consists of two concentric regions. The first of these is the inner fibers of the FR, beginning at the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Medial Habenula
The habenula (diminutive of Latin meaning rein) is a small bilateral neuronal structure in the brain of vertebrates, that has also been called a microstructure since it is no bigger than a pea. The naming as little rein describes its elongated shape in the epithalamus, where it borders the third ventricle, and lies in front of the pineal gland. Although it is a microstructure each habenular nucleus is divided into two distinct regions of nuclei, a medial habenula (MHb), and a lateral habenula (LHb) both having different neuronal populations, inputs, and outputs. The medial habenula can be subdivided into five subnuclei, the lateral habenula into four subnuclei. Research has shown morphological complexity in the MHb and LHb. Different inputs to the MHb are discriminated between the different subnuclei. In the two regions of nuclei there is a difference in gene expression giving different functions to each. The habenula is a conserved structure across vertebrates. In mammals it ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lower Motor Neuron
Lower motor neurons (LMNs) are motor neurons located in either the anterior grey column, anterior nerve roots (spinal lower motor neurons) or the cranial nerve nuclei of the brainstem and cranial nerves with motor function (cranial nerve lower motor neurons). Many voluntary movements rely on spinal lower motor neurons, which innervate skeletal muscle fibers and act as a link between upper motor neurons and muscles. Cranial nerve lower motor neurons also control some voluntary movements of the eyes, face and tongue, and contribute to chewing, swallowing and vocalization. Damage to lower motor neurons often leads to hypotonia, hyporeflexia, flaccid paralysis as well as muscle atrophy and fasciculations. Classification Lower motor neurons are classified based on the type of muscle fiber they innervate: * Alpha motor neurons (α-MNs) innervate extrafusal muscle fibers, the most numerous type of muscle fiber and the one involved in muscle contraction. * Beta motor neurons (β-M ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reticulospinal Tract
The reticular formation is a set of interconnected nuclei in the brainstem that spans from the lower end of the medulla oblongata to the upper end of the midbrain. The neurons of the reticular formation make up a complex set of neural networks in the core of the brainstem. The reticular formation is made up of a diffuse net-like formation of reticular nuclei which is not well-defined. It may be seen as being made up of all the interspersed cells in the brainstem between the more compact and named structures. The reticular formation is functionally divided into the ascending reticular activating system (ARAS), ascending pathways to the cerebral cortex, and the descending reticular system, descending pathways ( reticulospinal tracts) to the spinal cord. Due to its extent along the brainstem it may be divided into different areas such as the midbrain reticular formation, the central mesencephalic reticular formation, the pontine reticular formation, the paramedian pontine reticular ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypothalamus
The hypothalamus (: hypothalami; ) is a small part of the vertebrate brain that contains a number of nucleus (neuroanatomy), nuclei with a variety of functions. One of the most important functions is to link the nervous system to the endocrine system via the pituitary gland. The hypothalamus is located below the thalamus and is part of the limbic system. It forms the Basal (anatomy), basal part of the diencephalon. All vertebrate brains contain a hypothalamus. In humans, it is about the size of an Almond#Nut, almond. The hypothalamus has the function of regulating certain metabolic biological process, processes and other activities of the autonomic nervous system. It biosynthesis, synthesizes and secretes certain neurohormones, called releasing hormones or hypothalamic hormones, and these in turn stimulate or inhibit the secretion of hormones from the pituitary gland. The hypothalamus controls thermoregulation, body temperature, hunger (physiology), hunger, important aspects o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solitary Nucleus
The solitary nucleus (SN) (nucleus of the solitary tract, nucleus solitarius, or nucleus tractus solitarii) is a series of neurons whose cell bodies form a roughly vertical column of grey matter in the medulla oblongata of the brainstem. Their axons form the bulk of the enclosed solitary tract. The solitary nucleus can be divided into different parts including dorsomedial, dorsolateral, and ventrolateral subnuclei. The solitary nucleus receives general visceral and special visceral inputs from the facial nerve (CN VII), glossopharyngeal nerve (CN IX) and vagus nerve (CN X); it receives and relays stimuli related to taste and visceral sensation. It sends outputs to various parts of the brain, such as the hypothalamus, thalamus, and reticular formation, forming circuits that contribute to autonomic regulation. Cells along the length of the SN are arranged roughly in accordance with function; for instance, cells involved in taste are located in the rostral part, while those rec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dorsal Nucleus Of Vagus Nerve
The dorsal nucleus of vagus nerve (or posterior nucleus of vagus nerve or dorsal vagal nucleus or nucleus dorsalis nervi vagi or nucleus posterior nervi vagi) is a cranial nerve nucleus of the vagus nerve (CN X) situated in the medulla oblongata of the brainstem ventral to the floor of the fourth ventricle. It contains nerve cell bodies of parasympathetic neurons of CN X that provide parasympathetic innervation to the gastrointestinal tract and lungs as well as other thoracic and abdominal organs. These functions include, among others, bronchoconstriction and gland secretion. Cell bodies of pre-ganglionic parasympathetic neurons of CN X that innervate the heart meanwhile reside in the nucleus ambiguus, and additional cell bodies of the nucleus ambiguus give rise to the branchial efferent motor fibers of the vagus nerve (CN X) terminating in the laryngeal, and pharyngeal muscles, and musculus uvulae muscle. Additional images File:Gray694.png, Section of the medulla oblongata at a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rhomboid Fossa
The rhomboid fossa is a rhombus-shaped depression that is the anterior part of the fourth ventricle. Its anterior wall, formed by the back of the pons and the medulla oblongata, constitutes the floor of the fourth ventricle. It is covered by a thin layer of grey matter continuous with that of the spinal cord; superficial to this is a thin lamina of neuroglia which constitutes the ependyma of the Ventricular system, ventricle and supports a layer of ciliated epithelium. Parts The fossa consists of three parts, superior, intermediate, and inferior: ;The superior part :The superior part is triangular in shape and limited laterally by the superior cerebellar peduncle; its apex, directed upward, is continuous with the cerebral aqueduct; its base is represented by an imaginary line at the level of the upper ends of the superior foveae. ;The intermediate part :The intermediate part extends from this level to that of the horizontal portions of the Taenia of fourth ventricle, taeniae of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
