Cerebellar vermis
Encyclopedia
The cerebellar vermis is located in the medial, cortico-nuclear zone of the cerebellum
, residing in the posterior fossa
of the cranium. The primary fissure in the vermis curves ventrolaterally to the superior
surface of the cerebellum
, dividing it into anterior and posterior lobes. Functionally, the vermis is associated with bodily posture
and locomotion
. The vermis is included within the spinocerebellum and receives somatic sensory input from the head
and proximal body parts via ascending spinal pathways
.
The cerebellum
develops in a rostro-caudal manner, with rostral
regions in the midline giving rise to the vermis, and caudal regions developing into the cerebellar hemispheres. . By 4 months gestation
, the vermis becomes fully foliated
, while development of the hemispheres lags by 30-60 days. Postnatally, proliferation and organization of the cellular components of the cerebellum
continues, with completion of the foliation pattern by 7 months of life and final migration
, proliferation, and arborization
of cerebellar neurons by 20 months.
Inspection of the posterior fossa
is a common feature of prenatal ultrasound and is used primarily to determine whether excess fluid or malformations of the cerebellum exist. Anomalies of the cerebellar vermis are diagnosed in this manner and include phenotypes consistent with Dandy-Walker malformation, rhombencephalosynapsis, displaying no vermis with fusion of the cerebellar hemispheres, pontocerebellar hypoplasia
, or stunted growth of the cerebellum, and neoplasms. In neonates, hypoxic injury
to the cerebellum is fairly common, resulting in neuronal loss and gliosis. Symptoms of these disorders range from mild loss of fine motor control
to severe mental retardation
and death
. Karyotyping
has shown that most pathologies associated with the vermis are inherited though an autosomal recessive pattern, with most known mutations occurring on the X chromosome
.
The vermis is intimately associated with all regions of the cerebellar cortex, which can be divided into three functional parts, each having distinct connections with the brain
and spinal cord
. These regions are the vestibulocerebellum
, which is responsible primarily for the control of eye movements
; the spinocerebellum, involved in fine tune body and limb movement; and the cerebrocerebllum
, which is associated with planning, initiation and timing of movements.
. There are nine lobules of the vermis: lingula, central lobule, culmen, declive, folium of the vermis, tuber, pyramid, uvula and nodule. These lobules are often difficult to observe during human anatomy classes and may vary in size, shape and number of folia. It has been shown that folia of the cerebellum exhibit frequent variations in form, number and arrangement between individuals.
. The central lobule is the second lobule of the upper portion of the vermis on the superoinferior axis. The culmen is the third and largest lobule of the upper portion of the vermis on the superoinferior axis. It is separated from the declive by the primary fissure and is related with the anterior quadrangular lobule of the hemisphere.The pyramid is the seventh lobule of the vermis on the superoinferior axis. It is separated from the tuber and uvula by the pre-pyramidal and secondary fissures, respectively. This lobule is related with the biventral lobule of the hemisphere. The uvula is the second largest lobule, following the culmen. It pertains to the paleocerebellum and is separated from the nodule by the posterolateral fissure .
(including the spinocerebellar tract
) and from the trigeminal nerve
, as well as from visual and auditory
systems. It sends fibers to deep cerebellar nuclei that, in turn, project to both the cerebral cortex
and the brain stem
, thus providing modulation of descending motor systems. This region comprises the vermis and intermediate parts of the cerebellar hemispheres. Sensory information from the periphery and from the primary motor
and somatosensory cortex terminate in this region. Purkinje cells of the vermis project to the fastigial nucleus
, controlling the axial
and proximal musculature involved in the execution of limb movements. Purkinje
cells in the intermediate zone of the spinocerebellum project to the interposed nuclei, which control the distal musculature components of the descending motor pathways
needed for limb movement. Both of these nuclei include projections to the motor cortex
in the cerebrum.
is smaller than the dentate nucleus
but larger than the fastigial nucleus
and functions to modulate muscle stretch reflexes of distal musculature. It is located dorsal to the fourth ventricle
and lateral to the fastigial nucleus
; it receives afferent
neuronal supply from the anterior lobe
of the cerebellum and sends output via the superior cerebellar peduncle and the red nucleus
.
The fastigial nucleus is the most medial efferent
cerebellar nucleus, targeting the pontine and medullary reticular formation
as well as the vestibular nuclei
. This region deals with antigravity muscle groups and other synergies involved with standing and walking.. It is thought that fastigial nuclei axons are excitatory
and project beyond the cerebellum
, likely using glutamate and aspartate as neurotransmitters.
and in which the cerebellar vermis is completely absent, or present in a rudimentary form. It is also commonly associated with dysplasias
of brainstem nuclei.
suggest that retinal
and inertial
signals were selected for about 450 million years ago by primitive brainstem-cerebellar circuitry because of their relationship with the environment. Microscopically, it is evident that Purkinje cell
precursors arose from granule cells, first forming in irregular patterns, then progressively becoming organized in a layered fashion. Evolutionarily, the Purkinje cells then developed extensive dendritic trees
that increasingly became confined to a single plane, through which the axons of granule cells threaded, eventually forming a neuronal grid of right angles. The origin of the cerebellum
is in close association with that of the nuclei of the vestibular cranial nerve
and lateral line nerves, perhaps suggesting that this part of the cerebellum originated as a means of carrying out transformations of the coordinate system
from input data of the vestibular organ
and the lateral line organs
. This suggests that the function of the cerebellum evolved
as a mode of computing and representing an image relating to the position of the body in space. The cerebellar vermis evolved in conjunction with the hemispheres; this is seen in lampreys and higher vertebrates.
, or rhombencephalon
. This is the region of termination for the fibers
of the vestibular nerve
and lateral line nerves; thus, these are the oldest afferent paths
to the cerebellum and cerebellar vermis. In bony fish, or teleosts, it has been proposed that the cerebellar auricles, which receive a large amount of input from the vestibulolateral line system, constitute the vestibulocerebellum
and are homologues of the flocculonodular lobe
of higher vertebrates along with the corpus cerebelli
, which receives spinocerebellar and tectocerebellar fibers. The labyrinth
and the lateral line organs of lampreys have structural and functional similarity. An important difference between the two structures is that the arrangement of the lateral line organs are such that they are sensitive to relative motion of the fluid surrounding the animal, whereas the labyriths, having very similar sensing mechanisms, are sensitive to endolymph
, providing information concerning the animals’ own equilibrium
of the body and orientation in space
Cerebellum
The cerebellum is a region of the brain that plays an important role in motor control. It may also be involved in some cognitive functions such as attention and language, and in regulating fear and pleasure responses, but its movement-related functions are the most solidly established...
, residing in the posterior fossa
Posterior cranial fossa
The posterior cranial fossa is part of the intracranial cavity, located between the foramen magnum and tentorium cerebelli. It contains the brainstem and cerebellum.This is the most inferior of the fossae. It houses the cerebellum, medulla and pons....
of the cranium. The primary fissure in the vermis curves ventrolaterally to the superior
Anatomical terms of location
Standard anatomical terms of location are designations employed in science that deal with the anatomy of animals to avoid ambiguities that might otherwise arise. They are not language-specific, and thus require no translation...
surface of the cerebellum
Cerebellum
The cerebellum is a region of the brain that plays an important role in motor control. It may also be involved in some cognitive functions such as attention and language, and in regulating fear and pleasure responses, but its movement-related functions are the most solidly established...
, dividing it into anterior and posterior lobes. Functionally, the vermis is associated with bodily posture
Posture
Posture or posturing may refer to:In humans* Posture * Neutral spine or good posture* Human position* Abnormal posturing, in neurotrauma* Posturography, in neurology* Posture and occupational healthIn biology...
and locomotion
Locomotion
The term locomotion means movement or travel. It may refer to:* Motion * Animal locomotion** Terrestrial locomotion* TravelLocomotion may refer to specific types of motion:* Gait analysis* walking* running, including trotting...
. The vermis is included within the spinocerebellum and receives somatic sensory input from the head
Head
In anatomy, the head of an animal is the rostral part that usually comprises the brain, eyes, ears, nose and mouth . Some very simple animals may not have a head, but many bilaterally symmetric forms do....
and proximal body parts via ascending spinal pathways
Spinal cord
The spinal cord is a long, thin, tubular bundle of nervous tissue and support cells that extends from the brain . The brain and spinal cord together make up the central nervous system...
.
The cerebellum
Cerebellum
The cerebellum is a region of the brain that plays an important role in motor control. It may also be involved in some cognitive functions such as attention and language, and in regulating fear and pleasure responses, but its movement-related functions are the most solidly established...
develops in a rostro-caudal manner, with rostral
Rostral
Rostral can refer to:* Anatomical location or direction, towards the rostrum .* Rostral bone, in ceratopsian dinosaurs* Rostral column, a monumental scaled column, frequently decorated with ship bows* Rostral scale, in scaled reptiles...
regions in the midline giving rise to the vermis, and caudal regions developing into the cerebellar hemispheres. . By 4 months gestation
Gestation
Gestation is the carrying of an embryo or fetus inside a female viviparous animal. Mammals during pregnancy can have one or more gestations at the same time ....
, the vermis becomes fully foliated
Folium (brain)
A folium is a wrinkle on the surface of the cerebellum. The cortex of a folium consists of three layers of cells - the top molecular layer, the Purkinje layer, and the bottom granular layer - and this cortex covers deeper white matter ....
, while development of the hemispheres lags by 30-60 days. Postnatally, proliferation and organization of the cellular components of the cerebellum
Cerebellum
The cerebellum is a region of the brain that plays an important role in motor control. It may also be involved in some cognitive functions such as attention and language, and in regulating fear and pleasure responses, but its movement-related functions are the most solidly established...
continues, with completion of the foliation pattern by 7 months of life and final migration
Cell migration
Cell migration is a central process in the development and maintenance of multicellular organisms. Tissue formation during embryonic development, wound healing and immune responses all require the orchestrated movement of cells in particular directions to specific locations...
, proliferation, and arborization
Arbor vitae
-Anatomy:* Arbor vitae , white matter of the cerebellum* arbor vitæ uteri, a part of the canal of the cervix* Victorian slang for penis-Places:* Arbor Vitae, Wisconsin, a town, United States...
of cerebellar neurons by 20 months.
Inspection of the posterior fossa
Posterior fossa
Posterior fossa may refer to:* Posterior cranial fossa* Posterior intercondyloid fossa...
is a common feature of prenatal ultrasound and is used primarily to determine whether excess fluid or malformations of the cerebellum exist. Anomalies of the cerebellar vermis are diagnosed in this manner and include phenotypes consistent with Dandy-Walker malformation, rhombencephalosynapsis, displaying no vermis with fusion of the cerebellar hemispheres, pontocerebellar hypoplasia
Hypoplasia
Hypoplasia is underdevelopment or incomplete development of a tissue or organ. Although the term is not always used precisely, it properly refers to an inadequate or below-normal number of cells. Hypoplasia is similar to aplasia, but less severe. It is technically not the opposite of hyperplasia...
, or stunted growth of the cerebellum, and neoplasms. In neonates, hypoxic injury
Cerebral hypoxia
Cerebral hypoxia refers to a reduced supply of oxygen to the brain. Cerebral anoxia refers to a complete lack of oxygen to the brain. There are four separate categories of cerebral hypoxia; in order of severity they are; diffuse cerebral hypoxia , focal cerebral ischemia, cerebral infarction, and...
to the cerebellum is fairly common, resulting in neuronal loss and gliosis. Symptoms of these disorders range from mild loss of fine motor control
Motor control
Motor control are information processing related activities carried out by the central nervous system that organize the musculoskeletal system to create coordinated movements and skilled actions...
to severe mental retardation
Mental retardation
Mental retardation is a generalized disorder appearing before adulthood, characterized by significantly impaired cognitive functioning and deficits in two or more adaptive behaviors...
and death
Death
Death is the permanent termination of the biological functions that sustain a living organism. Phenomena which commonly bring about death include old age, predation, malnutrition, disease, and accidents or trauma resulting in terminal injury....
. Karyotyping
Karyotype
A karyotype is the number and appearance of chromosomes in the nucleus of an eukaryotic cell. The term is also used for the complete set of chromosomes in a species, or an individual organism.p28...
has shown that most pathologies associated with the vermis are inherited though an autosomal recessive pattern, with most known mutations occurring on the X chromosome
X chromosome
The X chromosome is one of the two sex-determining chromosomes in many animal species, including mammals and is common in both males and females. It is a part of the XY sex-determination system and X0 sex-determination system...
.
The vermis is intimately associated with all regions of the cerebellar cortex, which can be divided into three functional parts, each having distinct connections with the brain
Cerebral cortex
The cerebral cortex is a sheet of neural tissue that is outermost to the cerebrum of the mammalian brain. It plays a key role in memory, attention, perceptual awareness, thought, language, and consciousness. It is constituted of up to six horizontal layers, each of which has a different...
and spinal cord
Spinal cord
The spinal cord is a long, thin, tubular bundle of nervous tissue and support cells that extends from the brain . The brain and spinal cord together make up the central nervous system...
. These regions are the vestibulocerebellum
Cerebellum
The cerebellum is a region of the brain that plays an important role in motor control. It may also be involved in some cognitive functions such as attention and language, and in regulating fear and pleasure responses, but its movement-related functions are the most solidly established...
, which is responsible primarily for the control of eye movements
Eye movements
Eye movement is the voluntary or involuntary movement of the eyes, helping in acquiring, fixating and tracking visual stimuli. It may also compensate for a body movement, such as when moving the head...
; the spinocerebellum, involved in fine tune body and limb movement; and the cerebrocerebllum
Cerebellum
The cerebellum is a region of the brain that plays an important role in motor control. It may also be involved in some cognitive functions such as attention and language, and in regulating fear and pleasure responses, but its movement-related functions are the most solidly established...
, which is associated with planning, initiation and timing of movements.
Structure
The vermis is the unpaired, median portion of the cerebellum that connects the two hemispheres. Both the vermis and the hemispheres are composed of lobules formed by groups of foliaFolium (brain)
A folium is a wrinkle on the surface of the cerebellum. The cortex of a folium consists of three layers of cells - the top molecular layer, the Purkinje layer, and the bottom granular layer - and this cortex covers deeper white matter ....
. There are nine lobules of the vermis: lingula, central lobule, culmen, declive, folium of the vermis, tuber, pyramid, uvula and nodule. These lobules are often difficult to observe during human anatomy classes and may vary in size, shape and number of folia. It has been shown that folia of the cerebellum exhibit frequent variations in form, number and arrangement between individuals.
Lobe Anatomy
The lingula is the first lobule of the upper portion of the vermis on the superoinferior axis and pertains to the paleocerebellum together with the central lobule, culmen, pyramid and uvula. It is separated from the central lobule by the pre-central fissureFissure
In anatomy, a fissure is a groove, natural division, deep furrow, elongated cleft, or tear in various parts of the body.-Brain:...
. The central lobule is the second lobule of the upper portion of the vermis on the superoinferior axis. The culmen is the third and largest lobule of the upper portion of the vermis on the superoinferior axis. It is separated from the declive by the primary fissure and is related with the anterior quadrangular lobule of the hemisphere.The pyramid is the seventh lobule of the vermis on the superoinferior axis. It is separated from the tuber and uvula by the pre-pyramidal and secondary fissures, respectively. This lobule is related with the biventral lobule of the hemisphere. The uvula is the second largest lobule, following the culmen. It pertains to the paleocerebellum and is separated from the nodule by the posterolateral fissure .
Spinocerebellum
The spinocerebellum receives proprioception input from the dorsal columns of the spinal cordSpinal cord
The spinal cord is a long, thin, tubular bundle of nervous tissue and support cells that extends from the brain . The brain and spinal cord together make up the central nervous system...
(including the spinocerebellar tract
Spinocerebellar tract
The spinocerebellar tract is a set of axonal fibers originating in the spinal cord and terminating in the ipsilateral cerebellum. This tract conveys information to the cerebellum about limb and joint position ....
) and from the trigeminal nerve
Trigeminal nerve
The trigeminal nerve contains both sensory and motor fibres. It is responsible for sensation in the face and certain motor functions such as biting, chewing, and swallowing. Sensory information from the face and body is processed by parallel pathways in the central nervous system...
, as well as from visual and auditory
Auditory system
The auditory system is the sensory system for the sense of hearing.- Outer ear :The folds of cartilage surrounding the ear canal are called the pinna...
systems. It sends fibers to deep cerebellar nuclei that, in turn, project to both the cerebral cortex
Cerebral cortex
The cerebral cortex is a sheet of neural tissue that is outermost to the cerebrum of the mammalian brain. It plays a key role in memory, attention, perceptual awareness, thought, language, and consciousness. It is constituted of up to six horizontal layers, each of which has a different...
and the brain stem
Brain stem
In vertebrate anatomy the brainstem is the posterior part of the brain, adjoining and structurally continuous with the spinal cord. The brain stem provides the main motor and sensory innervation to the face and neck via the cranial nerves...
, thus providing modulation of descending motor systems. This region comprises the vermis and intermediate parts of the cerebellar hemispheres. Sensory information from the periphery and from the primary motor
Primary motor cortex
The primary motor cortex is a brain region that in humans is located in the posterior portion of the frontal lobe. Itworks in association with pre-motor areas to plan and execute movements. M1 contains large neurons known as Betz cells, which send long axons down the spinal cord to synapse onto...
and somatosensory cortex terminate in this region. Purkinje cells of the vermis project to the fastigial nucleus
Fastigial nucleus
The fastigial nucleus or nucleus fastigii refers specifically to the concentration of gray matter nearest to the middle line at the anterior end of the superior vermis, and immediately over the roof of the fourth ventricle, from which it is separated by a thin layer of white matter...
, controlling the axial
Axial
Axial may mean:* Along the same line as an axis of rotation in geometry* A type of modal frame in music* One of several anatomical directions in an animal body* Axial age, the period from 800 to 200 BC in China, India and the western world...
and proximal musculature involved in the execution of limb movements. Purkinje
Purkinje
Purkinje is a name attributed to several biological features, so named for their discovery by Czech anatomist Jan Evangelista Purkyně:*Purkinje cells, located in the cerebellum*Purkinje fibers, located in the heart*The visual Purkinje effect...
cells in the intermediate zone of the spinocerebellum project to the interposed nuclei, which control the distal musculature components of the descending motor pathways
Corticospinal tract
The corticospinal or pyramidal tract is a collection of axons that travel between the cerebral cortex of the brain and the spinal cord....
needed for limb movement. Both of these nuclei include projections to the motor cortex
Motor cortex
Motor cortex is a term that describes regions of the cerebral cortex involved in the planning, control, and execution of voluntary motor functions.-Anatomy of the motor cortex :The motor cortex can be divided into four main parts:...
in the cerebrum.
Nuclei
The interposed nucleusInterposed nucleus
The interposed nucleus is a deep nucleus of the cerebellum and is composed of the globose nuclei and the emboliform nuclei. It is located in the roof of the fourth ventricle, lateral to the fastigial nucleus...
is smaller than the dentate nucleus
Dentate nucleus
The dentate nucleus is located within the deep white matter of each cerebellar hemisphere, and it is the largest single structure linking the cerebellum to the rest of the brain. It is the largest and most lateral, or farthest from the midline, of the four pairs of deep cerebellar nuclei, the...
but larger than the fastigial nucleus
Fastigial nucleus
The fastigial nucleus or nucleus fastigii refers specifically to the concentration of gray matter nearest to the middle line at the anterior end of the superior vermis, and immediately over the roof of the fourth ventricle, from which it is separated by a thin layer of white matter...
and functions to modulate muscle stretch reflexes of distal musculature. It is located dorsal to the fourth ventricle
Ventricle
Ventricle may refer to:* Ventricle , the pumping chambers of the heart* Ventricular system in the brain* Ventricle of the larynx, a structure in the larynx* Stomach of the gastrointestinal tract...
and lateral to the fastigial nucleus
Fastigial nucleus
The fastigial nucleus or nucleus fastigii refers specifically to the concentration of gray matter nearest to the middle line at the anterior end of the superior vermis, and immediately over the roof of the fourth ventricle, from which it is separated by a thin layer of white matter...
; it receives afferent
Afferent
Afferent is an anatomical term with the following meanings:*Conveying towards a center, for example the afferent arterioles conveying blood towards the Bowman's capsule in the Kidney. Opposite to Efferent.*Something that so conducts, see Afferent nerve fiber...
neuronal supply from the anterior lobe
Cerebellum
The cerebellum is a region of the brain that plays an important role in motor control. It may also be involved in some cognitive functions such as attention and language, and in regulating fear and pleasure responses, but its movement-related functions are the most solidly established...
of the cerebellum and sends output via the superior cerebellar peduncle and the red nucleus
Red nucleus
The red nucleus is a structure in the rostral midbrain involved in motor coordination. It comprises a caudal magnocellular and a rostral parvocellular part.-Function:...
.
The fastigial nucleus is the most medial efferent
Efferent
Efferent is an anatomical term with the following meanings:*Conveying away from a center, for example the efferent arterioles conveying blood away from the Bowman's capsule in the kidney. Opposite to afferent....
cerebellar nucleus, targeting the pontine and medullary reticular formation
Reticular formation
The reticular formation is a part of the brain that is involved in actions such as awaking/sleeping cycle, and filtering incoming stimuli to discriminate irrelevant background stimuli...
as well as the vestibular nuclei
Vestibular nuclei
The vestibular nuclei are the cranial nuclei for the vestibular nerve.In Terminologia Anatomica they are grouped in both the pons and medulla.-Subnuclei:There are 4 subnuclei; they are situated at the floor of the fourth ventricle....
. This region deals with antigravity muscle groups and other synergies involved with standing and walking.. It is thought that fastigial nuclei axons are excitatory
Neuron
A neuron is an electrically excitable cell that processes and transmits information by electrical and chemical signaling. Chemical signaling occurs via synapses, specialized connections with other cells. Neurons connect to each other to form networks. Neurons are the core components of the nervous...
and project beyond the cerebellum
Cerebellum
The cerebellum is a region of the brain that plays an important role in motor control. It may also be involved in some cognitive functions such as attention and language, and in regulating fear and pleasure responses, but its movement-related functions are the most solidly established...
, likely using glutamate and aspartate as neurotransmitters.
Pathology
Dandy Walker malformation is a congenital brain malformation that is characterized by enlarged posterior fossaPosterior fossa
Posterior fossa may refer to:* Posterior cranial fossa* Posterior intercondyloid fossa...
and in which the cerebellar vermis is completely absent, or present in a rudimentary form. It is also commonly associated with dysplasias
Dysplasia
Dysplasia , is a term used in pathology to refer to an abnormality of development. This generally consists of an expansion of immature cells, with a corresponding decrease in the number and location of mature cells. Dysplasia is often indicative of an early neoplastic process...
of brainstem nuclei.
Comparative Anatomy
Early neurophysiologistsNeurologist
A neurologist is a physician who specializes in neurology, and is trained to investigate, or diagnose and treat neurological disorders.Neurology is the medical specialty related to the human nervous system. The nervous system encompasses the brain, spinal cord, and peripheral nerves. A specialist...
suggest that retinal
Retina
The vertebrate retina is a light-sensitive tissue lining the inner surface of the eye. The optics of the eye create an image of the visual world on the retina, which serves much the same function as the film in a camera. Light striking the retina initiates a cascade of chemical and electrical...
and inertial
Inertia
Inertia is the resistance of any physical object to a change in its state of motion or rest, or the tendency of an object to resist any change in its motion. It is proportional to an object's mass. The principle of inertia is one of the fundamental principles of classical physics which are used to...
signals were selected for about 450 million years ago by primitive brainstem-cerebellar circuitry because of their relationship with the environment. Microscopically, it is evident that Purkinje cell
Purkinje cell
For the cells of the electrical conduction system of the heart, see Purkinje fibersPurkinje cells, or Purkinje neurons , are a class of GABAergic neurons located in the cerebellar cortex...
precursors arose from granule cells, first forming in irregular patterns, then progressively becoming organized in a layered fashion. Evolutionarily, the Purkinje cells then developed extensive dendritic trees
Dendrite
Dendrites are the branched projections of a neuron that act to conduct the electrochemical stimulation received from other neural cells to the cell body, or soma, of the neuron from which the dendrites project...
that increasingly became confined to a single plane, through which the axons of granule cells threaded, eventually forming a neuronal grid of right angles. The origin of the cerebellum
Cerebellum
The cerebellum is a region of the brain that plays an important role in motor control. It may also be involved in some cognitive functions such as attention and language, and in regulating fear and pleasure responses, but its movement-related functions are the most solidly established...
is in close association with that of the nuclei of the vestibular cranial nerve
Vestibular nerve
The vestibular nerve is one of the two branches of the Vestibulocochlear nerve . It goes to the semicircular canals via the vestibular ganglion...
and lateral line nerves, perhaps suggesting that this part of the cerebellum originated as a means of carrying out transformations of the coordinate system
Coordinate system
In geometry, a coordinate system is a system which uses one or more numbers, or coordinates, to uniquely determine the position of a point or other geometric element. The order of the coordinates is significant and they are sometimes identified by their position in an ordered tuple and sometimes by...
from input data of the vestibular organ
Vestibular system
The vestibular system, which contributes to balance in most mammals and to the sense of spatial orientation, is the sensory system that provides the leading contribution about movement and sense of balance. Together with the cochlea, a part of the auditory system, it constitutes the labyrinth of...
and the lateral line organs
Lateral line
The lateral line is a sense organ in aquatic organisms , used to detect movement and vibration in the surrounding water. Lateral lines are usually visible as faint lines running lengthwise down each side, from the vicinity of the gill covers to the base of the tail...
. This suggests that the function of the cerebellum evolved
Evolution
Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...
as a mode of computing and representing an image relating to the position of the body in space. The cerebellar vermis evolved in conjunction with the hemispheres; this is seen in lampreys and higher vertebrates.
In Fish
In vertebrates, the cerebellar vermis develops between two bilaterally symmetrical formations located dorsal to the upper end of the medulla oblongataMedulla oblongata
The medulla oblongata is the lower half of the brainstem. In discussions of neurology and similar contexts where no ambiguity will result, it is often referred to as simply the medulla...
, or rhombencephalon
Rhombencephalon
The rhombencephalon is a developmental categorization of portions of the central nervous system in vertebrates.The rhombencephalon can be subdivided in a variable number of transversal swellings called rhombomeres...
. This is the region of termination for the fibers
Axon
An axon is a long, slender projection of a nerve cell, or neuron, that conducts electrical impulses away from the neuron's cell body or soma....
of the vestibular nerve
Vestibular nerve
The vestibular nerve is one of the two branches of the Vestibulocochlear nerve . It goes to the semicircular canals via the vestibular ganglion...
and lateral line nerves; thus, these are the oldest afferent paths
Afferent
Afferent is an anatomical term with the following meanings:*Conveying towards a center, for example the afferent arterioles conveying blood towards the Bowman's capsule in the Kidney. Opposite to Efferent.*Something that so conducts, see Afferent nerve fiber...
to the cerebellum and cerebellar vermis. In bony fish, or teleosts, it has been proposed that the cerebellar auricles, which receive a large amount of input from the vestibulolateral line system, constitute the vestibulocerebellum
Cerebellum
The cerebellum is a region of the brain that plays an important role in motor control. It may also be involved in some cognitive functions such as attention and language, and in regulating fear and pleasure responses, but its movement-related functions are the most solidly established...
and are homologues of the flocculonodular lobe
Flocculonodular lobe
The flocculonodular lobe is a lobe of the cerebellum consisting of the nodule and the flocculus.It is closely associated with the vestibulocerebellum. This lobe is involved in the maintenance of equilibrium.-External links:...
of higher vertebrates along with the corpus cerebelli
Cerebellum
The cerebellum is a region of the brain that plays an important role in motor control. It may also be involved in some cognitive functions such as attention and language, and in regulating fear and pleasure responses, but its movement-related functions are the most solidly established...
, which receives spinocerebellar and tectocerebellar fibers. The labyrinth
Labyrinth
In Greek mythology, the Labyrinth was an elaborate structure designed and built by the legendary artificer Daedalus for King Minos of Crete at Knossos...
and the lateral line organs of lampreys have structural and functional similarity. An important difference between the two structures is that the arrangement of the lateral line organs are such that they are sensitive to relative motion of the fluid surrounding the animal, whereas the labyriths, having very similar sensing mechanisms, are sensitive to endolymph
Endolymph
Endolymph is the fluid contained in the membranous labyrinth of the inner ear. It is also called Scarpa's fluid, after Antonio Scarpa.-Composition:...
, providing information concerning the animals’ own equilibrium
Equilibrium
Equilibrium is the condition of a system in which competing influences are balanced. The word may refer to:-Biology:* Equilibrioception, the sense of a balance present in human beings and other animals...
of the body and orientation in space
External links
- Photo - rollover to see highlighted at University of Texas Southwestern Medical Center at DallasUniversity of Texas Southwestern Medical Center at DallasThe University of Texas Southwestern Medical Center is one of the biomedical research institutions of the University of Texas System, incorporating three degree-granting institutions, four affiliated hospitals, including Parkland Memorial, the teaching hospital, and biomedical research...
- Diagram at medfriendly.com