Divisions Of Nervous System Diagram

Divisions Of Nervous System

Nervous system controls all the activities of the body, it is quicker than the other control system in the body namely, the endocrine system. Primarily, the nervous system is divided into two parts.

1. Central nervous system
2. Peripheral nervous system.

Read And Learn More: Medical Physiology Notes

1. Central Nervous System
   • The central nervous system (CNS) includes brain and spinal cord. It is formed by neurons and the supporting cells called neuroglia. The structures of brain and spinal cord are arranged in two layers namely, the gray matter and white matter. The gray matter is formed by nerve cell bodies and the proximal parts of nerve fibers arising from the nerve cell body. The white matter is formed by nerve fibers.
   • In brain the white matter is centrally placed and gray matter is in the outer part. In spinal cord white matter is in theouter part and gray matter is in the inner part.
   • Brain is situated in the skull. It is continued as spinal cord in the vertebral canal through the foramen magnum of the skull bone. Brain and spinal cord are surrounded by three layers of meninges called the outer dura mater, middle arachnoid mater, and inner pia mater.
   • The space between the arachnoid mater and the pia mater is known as subarachnoid space. This space is filled with a fluid called cerebrospinal fluid. The brain and spinal cord are actually suspended in the cerebrospinal fluid. The important parts of brain and segments of spinal cord are shown.
     • Parts of Brain: Brain consists of three major divisions:
       1. Prosencephalon
       2. Mesencephalon
       3. Rhombencephalon
          1. Prosencephalon: It is otherwise known as forebrain, it is further divided into two parts:
             1. Telencephalon which includes cerebral hemispheres, basal ganglia, hippocampus, and amygdaloid nucleus.
             2. Diencephalon consists of the thalamus, hypothalamus, metathalamus, and subthalamus.
          2. Mesencephalon: It is also known as midbrain.
          3. Rhombencephalon: The rhombencephalon or hindbrain is subdivided into two portions
             1. Metencephalon formed by pons and cerebellum
             2. Myelencephalon or medulla oblongata.
                • Midbrain, pons, and medulla oblongata are together called the brainstem.
2. Peripheral Nervous System: The peripheral nervous system (PNS) is formed by the neurons and their processes present in all regions of the body. It consists of cranial nerves arising from the brain and spinal nerves arising from the spinal cord. It is again divided into two subdivisions:
   1. Somatic nervous system
   2. Autonomic nervous system.

 

1. Somatic Nervous System: The somatic nervous system is concerned with somatic functions. It includes the nerves supplying the skeletal muscles. Somatic nervous system controls the movements of the body by acting on the skeletal muscles.
2. Autonomic Nervous System: The autonomic nervous system is concerned with the regulation of visceral or vegetative functions. So, it is otherwise called the vegetative or involuntary nervous system. The autonomic nervous system consists of two divisions, sympathetic division and parasympathetic division.