5. Classification of nervous system - CNS and PNS

The human nervous system is a complex network of specialised cells that allows us to sense, understand, and act on our surroundings. The brain handles most executive functions, whereas the spinal cord serves primarily as an information highway connecting the brain to numerous cells throughout the body.

 

The nervous system is divided into two categories:

 

  

The human central nervous system (CNS) is a network of about \(100\) billion nerve cells that regulates our activities, senses our surroundings, and defines who we are. Neurons are the CNS's functional units, and they are unique in their ability to transmit and store information.

 

Invertebrates primarily comprises a solid ventral nerve cord with ganglia. In some cases, brain may present.

 

The brain and the spinal cord are the two main elements of the CNS of vertebrates. The brain is located in the cranium/skull, and the spinal cord is found in the vertebral column.

 

Yes, in organisms, the central nervous system is the body's information processing, control, and coordination unit. It acts as the body's control and coordinating centre, transmitting and receiving information to and from muscles, glands, organs, and other body systems via the peripheral nervous system.

 

Our thoughts, movements, emotions, and desires are all controlled by the central nervous system. It also regulates our respiration, heart rate, hormone secretion, and body temperature.

 

Neurons, glial cells, axons, membranes, the neural tube, and the ventricular system are all important neuroanatomical features of the CNS. Neurons, synaptic transmission, and neurotransmitters are all important neurophysiological characteristics of the CNS.

The PNS is made up of all of the body's nerves connected to the CNS (brain and spinal cord).

 

 

Cranial nerves arising from the brain and spinal nerves arising from the spinal cord forms the peripheral nervous system. Both cranial and spinal nerves connect different parts of the body to the central nervous system. There are two types of nerve fibres in the PNS.

  

Nerves from the brain and spinal cord enter the peripheral nervous system. There are \(12\) cranial nerves and \(31\) pairs of spinal nerves in the human body.

The cranial nerves are a collection of twelve nerves that emerge from the brain. Each has a distinct sensory or movement function. The cranial nerves have sensory, motor, or mixed functions:

Each nerve has a number assigned to it based on its location in the brain and a name that reflects its function. The cranial nerves in the brain are labelled with Roman numerals ranging from I to XII.

 

The below picture depicts the twelve cranial nerve fibres names, location and their functions.

 

In humans, a totally of \(31\) pairs of spinal nerves are there, that emerge from the spinal cord. They are classified according to which regions of the spine they emerge from, such as the cervical, thoracic, lumbar, sacral, and coccygeal spinal nerves.

Spinal nerves are divided into five categories.