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 and
2. Peripheral nervous system.

Central Nervous System

The central nervous system 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 axons and dendrites. The white matter contains the nerve fibers.

Brain is situated in the skull. It is continued as spinal cord in the vertebral canal through the foremen 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 pia mater. The space between the arachnoid mater and 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.

Parts of Brain

Brain consists of three major divisions.
• Prosencephalon
• Mesencephalon and
• Rhombencephalon

Prosencephalon

This is otherwise known as fore brain. It is further divided into parts.
• Telencephalon, which includes the two cerebral hemispheres and
• Diencephalon, consisting of thalamus, hypothalamus, metathalamus and subthalamus.

Mesencephalon

This is also known as midbrain

Rhombencephalon

Rhombencephalon or hindbrain is subdivided into two portions.
• Metencephalon formed by pons and cerebellum and
• Myelencephalon or medulla oblongata.

Midbrain, pons and medulla oblongata are together called the brainstem.

Peripheral Nervous System

The peripheral nervous system is formed by the neurons and their processes present in all regions of the body. This consists of cranial nerves arising from brain and spinal nerves arising from the spinal cord. This is again divided into two subdivisions.

Somatic Nervous System

The somatic nervous system includes the nerves supplying the skeletal muscles. Somatic nervous system controls the movements of the body by acting on the skeletal muscles.

Autonomic Nervous System

The autonomic nervous system is concerned with regulation of visceral or vegetative functions. So, it is otherwise called vegetative or involuntary nervous system. The autonomic nervous system consists of two divisions, sympathetic division and parasympathetic division.