The peripheral nervous system is that part of the nervous system that is outside the brain and spinal cord. Through the peripheral nervous system, the brain and spinal cord regulate the functions of all systems, apparatus, organs and tissues.
In the nervous system, nerve cells do not lie in isolation. They come into contact with each other, forming chains of neurons - conductors of impulses. The long process of one neuron - the neurite (axon) comes into contact with short processes (dendrites) or the body of another neuron following the chain.
The oblong brain (medulla oblongata, s. Myelencephalon) is located between the hindbrain and the spinal cord. The upper border of the medulla oblongata on the ventral surface of the brain passes along the lower edge of the bridge.
The fourth (IV) ventriculus (ventriculus quartus) is a derivative of the cavity of the rhomboid brain. In the formation of the walls of the IV ventricle, the oblong brain, bridge, cerebellum and isthmus of the rhomboid brain participate.
The brain, as well as the dorsal one, is surrounded by three medullary membranes. These connective tissue sheets (membranes) cover the brain. The outermost of these shells is the hard shell of the brain.
The bridge (pons; variolium bridge) on the base of the trunk portion of the brain has the form of a transversely located cushion that borders the middle brain (with the legs of the brain) at the top (front) and the lower (behind) with the medulla oblongata.
The cerebellum (cerebellum, small brain) is located posteriorly (dorsally) from the bridge and from the upper (dorsal) part of the medulla oblongata. It lies in the posterior cranial fossa.
The posterior brain (metencephalon) includes a bridge located in front (ventrally), and the cerebellum, which is located behind the bridge. The cavity of the hindbrain, and with it the oblong one, is the IV ventricle.
The median brain (mesencephalon), unlike other parts of the brain, is less complicated. It distinguishes the roof and legs. The cavity of the middle brain is the aqueduct of the brain.
