Parts of the Nervous System – Anatomy
Peripheral Nervous System
Somatic Nervous System
The somatic nervous system is part of the peripheral nervous system, which is the entire nervous system outside of the brain and spinal cord. Specifically, the somatic nervous system is responsible for the movement of voluntary muscles and the process known as a reflex arc. This system carries nerve impulses back and forth between the central nervous system, which is the brain and the spinal cord, and the skeletal muscles, skin, and sensory organs.
Autonomic Nervous System
The autonomic nervous system regulates certain body processes, such as blood pressure and the rate of breathing. This system works automatically (autonomously), without a person’s conscious effort. Disorders of the autonomic nervous system can affect any body part or process. Autonomic disorders may result from other disorders that damage autonomic nerves (such as diabetes), or they may occur on their own. Autonomic disorders may be reversible or progressive.
Part of Brain
The main parts and their subdivisions are
The brainstem includes the midbrain, pons, and medulla. Hindbrain includes pons, medulla, and cerebellum. The dilated part of the central canal of the spinal cord within the conus medullaris is known as the terminal ventricle. Similarly, the cavity of septum pellucidum is sometimes called as the fifth ventricle.
Interesting facts About Brain
If a nerve is injured or cut, a series of degenerative and then regenerative change follow. The degenerative changes occur in
Cell Body: It undergoes chromatolysis.Nissl granules disappear, the cell becomes swollen and rounded; and the nucleus is pushed to the periphery.
The proximal part of the cut fiber: So long the mother cell is intact, it survives, and only a part near the cut end degenerates.
The distal part of the cut fiber: It degenerates completely. Axis cylinder becomes fragmented; multiple sheaths break up into fat droplets and nuclei of Schwann cells multiply and fill up the neurilemmal tube. During regeneration, the tip of the axon still connected with the cell body begins to grow through the neurilemmal tube. The rate of growth is about 1 -2 mm per day in man. Myelin sheath is reformed. The role of the neurilemmal tube as a guiding factor to the regenerating proximal axon is considered to be of paramount importance.
Thus a nerve can regenerate because it has a neurilemmal sheath. A tract cannot regenerate because it has no such sheath.
Read related post