Organization of the Nervous System
Overview of the Nervous System
The nervous system is anatomically divided into the central nervous system (CNS) and the peripheral nervous system (PNS). The CNS is made up of the brain and spinal cord. The PNS consists of both cranial and spinal nerves that act as conduits for information travelling between the body and the CNS. The PNS can be functionally subdivided into sensory and motor components. The motor division of the PNS is subdivided into the somatic nervous system that primarily controls voluntary activities and the visceral efferent nervous system that primarily controls involuntary activities. The visceral motor system is also called the autonomic nervous system (ANS). It has two branches: the sympathetic nervous system and parasympathetic system ().
The Central Nervous System
The CNS is composed of the brain and spinal cord ().
The brain can be divided into the following major structures: cerebrum, brainstem, and cerebellum ().
The cerebrum is made up of two cerebral hemispheres, each containing several lobes.
The midbrain, pons, and medulla make up the brainstem.
The cerebellum has lobes and hemispheres as well as a midline structure known as the vermis.
The brain resides in the cranium while the spinal cord is contained within the vertebral column.
The function of the CNS is to process and coordinate information that is received from the body and then direct the appropriate responses necessary for the maintenance of normal activity.
The CNS is composed of neurons (a, b), which transmit impulses and neuroglial cells (c), which perform a more supportive function in maintaining homeostasis. Neuroglia do not transmit impulses
The gray and white matter of the CNS is largely made up of the cell bodies of neurons and the myelinated axons of neurons, respectively ().
