The cerebellar vermis is a structure of the brain's cerebellum that has a narrow, worm-like shape. Named after the Latin term for "little brain," the cerebellum is a small portion of the brain's rear lower region that is instrumental in the body's coordination and movement. Thus, as part of the cerebellum, the cerebellar vermis plays a part in these two functions.
Placed underneath the brain's two regions called cerebral hemispheres, which are created by the even split of a deep groove called the medial longitudinal fissure, the cerebellum appears as a distinct structure. The cerebellar vermis is the cerebellum's median, or central, portion. This means that it is placed between the two hemispheres, consequently joining both regions.
The cerebellar vermis mainly consists of two portions, or lobes. The top portion is referred to as the superior cerebellar vermis, while the bottom portion is referred to as inferior cerebellar vermis. The structure is subdivided into nine lobules, which are the central, culmen, declive, folium, lingula, nodulus, pyramid, tuber and uvula.
The main responsibility of this area is proprioception, which is the ability to recognize the relative positioning of body parts used for movement. This portion of the cerebellum accomplishes proprioception by comparing the motor commands from the brain with the sensations it receives from the spine. The vermis uses this data to determine the appropriate spatial positions of body parts. It also assists in correcting movements so that the body moves normally according to timing and sequencing. The body parts that the vermis is involved with include the neck, hips and shoulders.
Also included among the functions of the vermis is the control of muscle tone and level of force. Muscle tone indicates for the level of tension present in the muscles. Level of force denotes the amount of work that the body needs from the muscles for movements, including rapid and sequential moves.
The cerebellar vermis is clinically significant for a medical condition called Dandy-Walker Syndrome (DWS). It is also known as Dandy-Walker complex or Dandy-Walker malformation. Named after American neurosurgeons Walter Edward Dandy and Arthur Earl Walker, who first described the ailment, DWS involves a vermis that is partially or completely missing.
DWS is typically associated with the enlargement of brainstem nuclei and increase of the cerebrospinal fluid upon which the brain floats. Its occurrence is sporadic, but most commonly affecting females and children. Treatment of DWS usually involves removing the excess fluid using a specialized tube.