What Are Cerebellar Peduncles?

Cerebellar peduncles are stalk-like bundles of nerve fibers that connect the cerebellum with the brain stem. The cerebellum is the part of the brain that is responsible for one's cognitive functions, which include language, memory, attention and problem solving. It also plays a major role in motor control, which involves the movement of muscles and limbs. There are three types of cerebellar peduncles: superior cerebellar peduncle, middle cerebellar peduncle and inferior cerebellar peduncle.

There are two superior cerebellar peduncles, which are also known collectively as brachia conjunctiva, so named because they can be found at the cerebellum's upper part. They emerge from both halves of the cerebellum, which are called hemispheres. These peduncles create the boundaries at the upper sides of the fourth ventricle, which is one of the brain's connected fluid-filled holes. The superior cerebellar peduncles contribute to the coordination of the arms and legs. Also, some nerve fibers go through the superior cerebellar peduncles when they are transporting information from the cerebellum to the midbrain, or mesencephalon, and the portion of the brain stem known as pons.

The two middle cerebellar peduncles, or brachia pontis, are located at the middle of the cerebellum between the brachia conjunctiva and inferior peduncle. They originate from the pontine nuclei, which are the part of the pons specifically responsible for storing memory of intention for motor control. They terminate at a sheet of grey matter at the cerebellum called the cerebellar cortex.

Three types of nervous tissue, or fasciculus, compose the middle cerebellar peduncles: superior, inferior and deep. The superior fasciculus, which is located at the surface of the cerebellum, comes from the pons' upper transverse fibers. The inferior fasciculus is so named because originates from the pons' bottom transverse fibers. The superior and inferior fasciculi cover part of the deep fasciculus, which is derived from the pons' deep transverse fibers.

The inferior cerebellar peduncle is appropriately named after its positioning behind the superior and middle cerebellar peduncles. It is responsible for connecting the body's sense of perception with its vestibular system. This is the sensory system responsible for functions such as posture and balance as well as the sense of spatial orientation — basically, it prevents humans from falling over when standing or walking. The inferior cerebellar peduncle, located at the lower portion of the fourth ventricle, accomplishes this task by connecting the cerebellum with the spinal cord.