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Olfactory Tract
The olfactory tract is a bilateral bundle of afferent nerve fibers from the mitral and tufted cells of the olfactory bulb that connects to several target regions in the brain, including the piriform cortex, amygdala, and entorhinal cortex. It is a narrow white band, triangular on coronal section, the apex being directed upward. Structure The olfactory tract and olfactory bulb lie in the olfactory sulcus a sulcus formed by the medial orbital gyrus on the inferior surface of each frontal lobe. The olfactory tracts lie in the sulci which run closely parallel to the midline. Fibers of the olfactory tract appear to end in the antero-lateral part of the olfactory tubercle, the dorsal and external parts of the anterior olfactory nucleus, the frontal and temporal parts of the prepyriform area, the cortico-medial group of amygdala nuclei and the nucleus of the stria terminalis. The olfactory tract divides posteriorly into a medial and a lateral stria. Caudal to this is the olfactor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Olfactory System
The olfactory system, or sense of smell, is the sensory system used for smelling (olfaction). Olfaction is one of the special senses, that have directly associated specific organs. Most mammals and reptiles have a main olfactory system and an accessory olfactory system. The main olfactory system detects airborne substances, while the accessory system senses fluid-phase stimuli. The senses of smell and taste (gustatory system) are often referred to together as the chemosensory system, because they both give the brain information about the chemical composition of objects through a process called transduction. Structure Peripheral The peripheral olfactory system consists mainly of the nostrils, ethmoid bone, nasal cavity, and the olfactory epithelium (layers of thin tissue covered in mucus that line the nasal cavity). The primary components of the layers of epithelial tissue are the mucous membranes, olfactory glands, olfactory neurons, and nerve fibers of the olfactory nerves. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prepyriform Area
Prepyriform area (or prepiriform cortex) is a portion of the rhinencephalon consisting of paleocortex. Some sources state that it is part of the primary olfactory cortex The primary olfactory cortex (POC) is a portion of the cerebral cortex. It is found in the inferior part of the temporal lobe of the brain. It receives input from the olfactory tract. It is involved in the sense of smell (olfaction). Structure .... Prepyriform Cortex along with Pyriform cortex And Cortical portion of amygdaloid nuclei constitute lateral olfactory area which send signal to almost all portion of limbic system such as hippocampus, which seem to be most important area for learning to like and dislike foods depending upon one's experience with them. References Cerebral cortex Olfactory system {{neuroanatomy-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rhinencephalon
In animal anatomy, the rhinencephalon (from the Greek, ῥίς, ''rhis'' = "nose", and ἐγκέφαλος, ''enkephalos'' = "brain"), also called the smell-brain or olfactory brain, is a part of the brain involved with smell (i.e. olfaction). It forms the paleocortex and is rudimentary in the human brain. Components The term ''rhinencephalon'' has been used to describe different structures at different points in time. One definition includes the olfactory bulb, olfactory tract, anterior olfactory nucleus, anterior perforated substance, medial olfactory stria, lateral olfactory stria, parts of the amygdala and prepyriform area. Some references classify other areas of the brain related to perception of smell as rhinencephalon, but areas of the human brain that receive fibers strictly from the olfactory bulb are limited to those of the paleopallium. As such, the rhinencephalon includes the olfactory bulb, the olfactory tract, the olfactory tubercle and striae, the anterior olf ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genetic Disorder
A genetic disorder is a health problem caused by one or more abnormalities in the genome. It can be caused by a mutation in a single gene (monogenic) or multiple genes (polygenic) or by a chromosomal abnormality. Although polygenic disorders are the most common, the term is mostly used when discussing disorders with a single genetic cause, either in a gene or chromosome. The mutation responsible can occur spontaneously before embryonic development (a ''de novo'' mutation), or it can be Heredity, inherited from two parents who are carriers of a faulty gene (autosomal recessive inheritance) or from a parent with the disorder (autosomal dominant inheritance). When the genetic disorder is inherited from one or both parents, it is also classified as a hereditary disease. Some disorders are caused by a mutation on the X chromosome and have X-linked inheritance. Very few disorders are inherited on the Y linkage, Y chromosome or Mitochondrial disease#Causes, mitochondrial DNA (due to t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kallmann Syndrome
Kallmann syndrome (KS) is a genetic disorder that prevents a person from starting or fully completing puberty. Kallmann syndrome is a form of a group of conditions termed hypogonadotropic hypogonadism. To distinguish it from other forms of hypogonadotropic hypogonadism, Kallmann syndrome has the additional symptom of a total lack of sense of smell (anosmia) or a reduced sense of smell. If left untreated, people will have poorly defined secondary sexual characteristics, show signs of hypogonadism, almost invariably are infertile and are at increased risk of developing osteoporosis. A range of other physical symptoms affecting the face, hands and skeletal system can also occur. The underlying cause is a failure in the correct production or activity of gonadotropin-releasing hormone by the hypothalamus. This results in low levels of the sex hormones testosterone in males or oestrogen and progesterone in females. Diagnosis normally occurs during teenage years when puberty fails ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hyposmia
Hyposmia, or microsmia, is a reduced ability to smell and to detect odors. A related condition is anosmia, in which no odors can be detected. Some of the causes of olfaction problems are allergies, nasal polyps, viral infections and head trauma. In 2012 an estimated 9.8 million people aged 40 and older in the United States had hyposmia and an additional 3.4 million had anosmia/severe hyposmia. Hyposmia might be a very early sign of Parkinson's disease.Factor, Stewart A., & Weiner, William J., eds. (2008). ''Parkinson's Disease: Diagnosis and Clinical Management'', 2nd ed., pp. 72-73. New York: Demos Medical Publishing. Hyposmia is also an early and almost universal finding in Alzheimer's disease and dementia with Lewy bodies. Lifelong hyposmia could be caused by Kallmann syndrome or Autism Spectrum Disorder. Along with other chemosensory disturbances, hyposmia can be a key indicator of COVID-19. Epidemiology The National Health and Nutrition Examination Survey (NHANES) collect ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anosmia
Anosmia, also known as smell blindness, is the loss of the ability to detect one or more smells. Anosmia may be temporary or permanent. It differs from hyposmia, which is a decreased sensitivity to some or all smells. Anosmia can be due to a number of factors, including an inflammation of the nasal mucosa, blockage of nasal passages or a destruction of one temporal lobe. Inflammation is due to chronic mucosa changes in the lining of the paranasal sinus and in the middle and superior turbinates. When anosmia is caused by inflammatory changes in the nasal passageways, it is treated simply by reducing inflammation. It can be caused by chronic meningitis and neurosyphilis that would increase intracranial pressure over a long period of time, and in some cases by ciliopathy, including ciliopathy due to primary ciliary dyskinesia. The term derives from the New Latin ''anosmia'', based on Ancient Greek ἀν- (''an''-) + ὀσμή (''osmḗ'' 'smell'; another related term, hyperosmia, r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parahippocampal Gyrus
The parahippocampal gyrus (or hippocampal gyrus') is a grey matter cortical region of the brain that surrounds the hippocampus and is part of the limbic system. The region plays an important role in memory encoding and retrieval. It has been involved in some cases of hippocampal sclerosis. Asymmetry has been observed in schizophrenia. Structure The anterior part of the gyrus includes the perirhinal and entorhinal cortices. The term parahippocampal cortex is used to refer to an area that encompasses both the posterior parahippocampal gyrus and the medial portion of the fusiform gyrus. Function Scene recognition The parahippocampal place area (PPA) is a sub-region of the parahippocampal cortex that lies medially in the inferior temporo-occipital cortex. PPA plays an important role in the encoding and recognition of environmental scenes (rather than faces). fMRI studies indicate that this region of the brain becomes highly active when human subjects view topographical scene sti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Uncus
The uncus is an anterior extremity of the parahippocampal gyrus. It is separated from the apex of the temporal lobe by a slight fissure called the incisura temporalis (also called rhinal sulcus). Although superficially continuous with the hippocampal gyrus, the uncus forms morphologically a part of the rhinencephalon. An important landmark that crosses the inferior surface of the uncus is the band of Giacomini. The term comes from the Latin word uncus, meaning ''hook'', and it was coined by Félix Vicq-d'Azyr (1748–1794).JC Tamraz, YG Comair. Atlas of Regional Anatomy of the Brain Using MRI (2006), p 8. Clinical significance The part of the olfactory cortex that is on the temporal lobe covers the area of the uncus, which leads into the two significant clinical aspects of the uncus: uncinate fits and uncal herniations. * Seizures, often preceded by hallucinations of disagreeable odors, often originate in the uncus. * In situations of tumor, hemorrhage, or edema, increased ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Subcallosal Gyrus
The subcallosal gyrus (paraterminal gyrus, peduncle of the corpus callosum) is a narrow lamina on the medial surface of the hemisphere in front of the lamina terminalis, behind the parolfactory area, and below the rostrum of the corpus callosum. It is continuous around the genu of the corpus callosum The corpus callosum (Latin for "tough body"), also callosal commissure, is a wide, thick nerve tract, consisting of a flat bundle of commissural fibers, beneath the cerebral cortex in the brain. The corpus callosum is only found in placental ma ... with the indusium griseum. It's also considered a part of limbic system of the brain. References External links * Limbic system Gyri {{neuroanatomy-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parolfactory Area
The subcallosal area (parolfactory area of Broca) is a small triangular field on the medial surface of the hemisphere in front of the subcallosal gyrus, from which it is separated by the posterior parolfactory sulcus; it is continuous below with the olfactory trigone, and above and in front with the cingulate gyrus; it is limited anteriorly by the anterior parolfactory sulcus. The subcallosal area is also known as "Zuckerkandl's gyrus", for Emil Zuckerkandl. The parahippocampal gyrus, subcallosal area, and cingulate gyrus have been described together as the periarcheocortex. The "subcallosal area" and "parolfactory area" are considered equivalent in BrainInfo, but in Terminologia Anatomica ''Terminologia Anatomica'' is the international standard for human anatomical terminology. It is developed by the Federative International Programme on Anatomical Terminology, a program of the International Federation of Associations of Anatomis ... they are considered distinct structures. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anterior Perforated Substance
The anterior perforated substance is a part of the brain. It is bilateral. It is irregular and quadrilateral. It lies in front of the optic tract and behind the olfactory trigone. Structure The anterior perforated substance is bilateral. It lies in front of the optic tract. It lies behind the olfactory trigone, separated by the fissure prima. Medially and in front, it is continuous with the subcallosal gyrus. Laterally, it is bounded by the lateral stria of the olfactory tract, and is continued into the uncus. Its gray substance is confluent above with that of the corpus striatum, and is perforated anteriorly by numerous small blood vessels that supply such areas as the internal capsule. The anterior cerebral artery arises just below the anterior perforated substance. The middle cerebral artery passes through its lateral two thirds. Blood supply The anterior perforated substance is supplied by lenticulostriate arteries, which branch from the middle cerebral artery. It i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
