Cerebellar vermis

File:Sobo 1909 655 Cerebellar vermis.png

The vermis is the unpaired, median portion of the cerebellum that connects the two hemispheres.{{cite journal |author=Monte-Bispo, R.F. |title=Cerebellar Vermis: Topography and Variations |journal=Int. J. Morphol. |volume=28 |issue=2 |pages=439–443 |year=2010 |doi=10.4067/s0717-95022010000200018 |display-authors=etal |doi-access=free}} Both the vermis and the hemispheres are composed of lobules formed by groups of folia. There are nine lobules of the vermis: lingula, central lobule, culmen, clivus, 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.

File:CerebellumDiv.png

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 fissure. 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.

The spinocerebellum receives proprioception input from the dorsal columns of the spinal cord (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.{{cite book |author= Ramon-Cajal, S. |title= Histology of the Nervous System |publisher= Oxford University Press |year=1995}} 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.

The interposed nucleus 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.{{cite book|title=Neurology for the Boards|author1=James D. Geyer |author2=Janice M. Keating |author3=Daniel C. Potts |publisher=Lippincott-Raven|year=1998|location=Philadelphia|page=9}} It is thought that fastigial nuclei axons are excitatory and project beyond the cerebellum, likely using glutamate and aspartate as neurotransmitters.

Malformations of the posterior fossa have been recognized more frequently during the past few decades as the result of recent advances in technology. Malformations of the cerebellar vermis were first identified using pneumoencephalography, where air is injected into the cerebrospinal fluid spaces of the cerebellum; displaced, occluded or dysplastic structures could be identified. Upon the advent of computerized tomography (CT) and magnetic resonance imaging (MRI), the resolution of cranial structures including the mid-hindbrain regions improved dramatically.{{cite journal|last1=Patel|first1=Sandeep|last2=Barkovich|first2=A. James |title=Analysis and classification of cerebellar malformations |journal=American Journal of Neuroradiology |date=2002 |volume=23 |issue=7 |pages=1074–1087 |pmid=12169461 |pmc=8185716}}

Joubert syndrome (JS) is one of the most commonly diagnosed syndromes associated with the molar tooth sign (MTS),{{cite journal |vauthors=Brancati F, Dallapiccola B, Valente EM |title=Joubert Syndrome and related disorders |journal=Orphanet Journal of Rare Diseases |volume=5 |pages=20 |year=2010 |pmid=20615230 |pmc=2913941 |doi=10.1186/1750-1172-5-20 |doi-access=free }} or hypoplasia/dysplasia of the cerebellar vermis accompanied by brainstem abnormalities. JS is defined clinically by features of hypotonia in infancy with later development of ataxia, developmental delays, mental retardation, abnormal breathing patterns, abnormal eye movements specific to oculomotor apraxia, or the presence of the MTS on the cranial MRI.{{cite journal |author1=J.M. Saraiva |author2=M. Baraitser |title=Joubert syndrome: a review |journal= American Journal of Medical Genetics |volume= 43 |pages= 726–731 |year=1992|pmid=1341417 |doi=10.1002/ajmg.1320430415 |issue=4}}{{cite journal |author1=B.L. Maria |author2=E. Boltshauser |author3=S.C. Palmer |author4=T.X. Tran |s2cid=7410607 |title= Clinical features and revised diagnostic criteria in Joubert syndrome |journal=Child Neurology |volume=14 |pages= 583–590 |year=1999 |doi=10.1177/088307389901400906 |issue=9 |pmid=10488903}} JS is an autosomal recessive condition with an estimated prevalence of 1: 100,000.{{cite book |author1=D.B. Flannery |author2=J.G. Hudson |title=A survey of Joubert syndrome |publisher= David W. Smith Workshop |year=1994}}

Dandy Walker malformation is a relatively common congenital brain malformation with a prevalence of 1:30,000 live births.{{cite journal |last1=Osenbach |first1=R.K. |last2=Menezes |first2=A.H. |title=Diagnosis and management of the Dandy-Walker malformation: 30 years of experience |journal=Pediatric Neurosurgery |date=1992 |volume=18 |issue=4 |pages=179–89 |doi=10.1159/000120660 |pmid=1472430}} Dandy Walker malformation is characterized by enlarged posterior fossa and in which the cerebellar vermis is completely absent, or present in a rudimentary form, sometimes rotated accompanied by an elevation of the fourth ventricle. It is also commonly associated with dysplasias of brainstem nuclei.{{cite journal |author1=Kapur, R. |author2=Mahony, B. |author3=Finch, L. |author4=Siebert J. |title=Normal and Abnormal Anatomy of the Cerebellar Vermis in Midgestational Human Fetuses |journal=Birth Defects Research |volume=85 |pages=700–709 |year=2009 |doi=10.1002/bdra.20589 |pmid=19441098 |issue=8}} DWM has been reported to be in association with a wide array of chromosomal anomalies, including trisomy 18, trisomy 9, and trisomy 13. Surveys suggest that prenatal exposure to teratogens such as rubella or alcohol are correlated with development of Dandy Walker malformation.{{cite journal |author1=J.C. Murray |author2=J.A. Johnson |author3=T.D. Bird |title=Dandy–Walker malformation: etiologic heterogeneity and empiric recurrence risks |journal=Clin. Genet. |volume= 28 |pages= 272–283 |year=1985 |pmid= 4064366 |issue= 4|doi=10.1111/j.1399-0004.1985.tb00401.x |s2cid=22883753 }}{{cite journal |author1=S.K. Clarren |author2=J. Alvord |author3=S.M. Sumi |title=Brain malformations related to prenatal exposure to ethanol |journal=Journal of Pediatrics |volume= 92 |issue=1 |pages= 64–67 |year=1978 |doi=10.1016/S0022-3476(78)80072-9 |pmid=619080}}

Rhombencephalosynapsis is an anomaly characterized by the absence or severe dysgenesis of the cerebellar vermis with fusion of the cerebellar hemispheres, peduncles, and dentate nuclei. Diagnostic features include fusion of the midbrain colliculi, hydrocephalus, absence of the corpus callosum other midline structural brain malformations.{{cite journal |author1=S.P. Toelle |author2=C. Yalcinkaya |author3=N. Kocer |author4=T. Deonna |author5=W.C.G. Overweg-Plandsoen |author6=T. Bast |author7=R. Kalmanchey |author8=P. Barsi |author9=J.F.L. Schneider |author10=A. Capone Mori |author11=E. Boltshauser |title=Rhombencephalosynapsis: clinical findings and neuroimaging in 9 children |journal= Neuropediatrics |volume= 33 |issue=4 |pages= 209–214 |year=2002 |doi=10.1055/s-2002-34498|pmid=12368992 |s2cid=32510022 }}{{cite journal |author1=H. Utsunomiya |author2=K. Takano |author3=T. Ogasawara |author4=T. Hashimoto |author5=T. Fukushima |author6=M. Okazaki |title=Rhombencephalosynapsis: cerebellar embryogenesis |journal=American Journal of Neuroradiology |volume=19 |pages=547–549 |year=1998 |pmid=9541316 |issue=3 |pmc=8338264}}{{cite journal |author1=C.L. Truwit |author2=A.J. Barkovich |author3=R. Shanahan |author4=T.V. Maroldo |title=MR imaging of rhomboencephalosynapsis: report of three cases and review of the literature |journal=American Journal of Neuroradiology |volume=12 |pages=957–965 |year=1991 |pmid=1950929 |issue=5 |pmc=8333516}}

Hypoplasia and other structural alterations of the vermis have been identified in many patients with autism spectrum disorder (ASD). While the exact nature and extent of the impacts ASD has on the vermis remain in question, it has also been shown that other injuries and malformations of the vermis sometimes produce symptoms closely analogous to ASD. Furthermore, several genetic syndromes known to cause autism (such as fragile X syndrome) have also been shown to cause damage to the vermis.{{Cite journal |last1=Hampson |first1=David R. |last2=Blatt |first2=Gene J. |date=2015 |title=Autism spectrum disorders and neuropathology of the cerebellum |journal=Frontiers in Neuroscience |volume=9 |pages=420 |doi=10.3389/fnins.2015.00420 |doi-access=free |issn=1662-4548 |pmc=4635214 |pmid=26594141}}

Lesions to the vermis commonly give rise to clinical depression, inappropriate emotional displays (e.g. unwarranted giggling) in addition to movement disorders. {{citation needed|date=March 2016}}

Early neurophysiologists 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.{{cite book |title=The Human Central Nervous System: A Synopsis and Atlas |author1=Nieuwenhuys, R. |author2=Voogd, J. |author3=van Huijzen, C. |edition=3rd |place=Heidelberg |publisher=Springer-Verlag |year=1988}} 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.{{cite book |title=Comparative Vertebrate Neuroanatomy: Evolution and Adaptation |chapter=12: The Cerebellum |pages=180–197 |author1=Butler, A.B. |author2=Hodos, W. |place=New York |publisher=Wiley-Liss |year=1996}} 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.{{cite book |title=The Comparative Anatomy of the Nervous System of Vertebrates, Including Man |volume=3 |author1=Ariens, K. |author2=C.U. |author3=Huber, G.C. |author4=Crosby, E.C. |place=New York |publisher=Hafner |year=1960}}

In vertebrates, the cerebellar vermis develops between two bilaterally symmetrical formations located dorsal to the upper end of the medulla oblongata, 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 labyrinths, having very similar sensing mechanisms, are sensitive to endolymph, providing information concerning the animal's own equilibrium of the body and orientation in space.

• cerebellar vermis hypoplasia, a genetic ciliopathy
• Anatomy of the cerebellum

File:Vermis and paravermis by Sanjoy Sanyal.webm|Dissection video. Explains the position of vermis.

File:Cerebellar vermis --- animation.gif|Animation. Vermis is highlighted in red.

File:Slide2BRA.JPG|Brainstem. Posterior view.

File:Human brain midsagittal view description.JPG|Midsagittal view

File:Cerebellar lobes and lobules.png|Lobules of the vermis.

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• [https://web.archive.org/web/20151022121646/http://werenotlikeyou.com/ We're Not Like You]

Rhombencephalosynapsis Website Support

• [https://web.archive.org/web/20060207073701/http://pathcuric1.swmed.edu/PathDemo/CNS1/cns1190.htm Photo - rollover to see highlighted] at University of Texas Southwestern Medical Center at Dallas
• [http://www.medfriendly.com/cerebellarvermis.html#whatisit Diagram] at medfriendly.com
• {{BrainMaps|Vermis}}
• {{cite web|url=http://www.tk.de/rochelexikon/pics/s13048.000-3.html|title=Anatomy diagram: 13048.000-3|website= Roche Lexicon - illustrated navigator|publisher= Elsevier|archive-url=https://web.archive.org/web/20120722052451/http://www.tk.de/rochelexikon/pics/s13048.000-3.html|archive-date=2012-07-22}}
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