Organization of the Nervous System
Describe the function of the nervous system.
Describe the components of CNS and PNS.
Describe the divisions and subdivisions of the PNS.
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 ().
Fig. 1.1 The nervous system is divided into the central (CNS) and peripheral (PNS) nervous systems. The CNS consists of the brain and spinal cord, which constitute a functional unit. The PNS consists of the nerves emerging from the brain and spinal cord (cranial and spinal nerves, respectively).
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 ().
Fig. 1.2 The central nervous system (CNS) is composed of the brain and spinal cord. (Reproduced with permission from Gilroy AM, MacPherson BR. Atlas of Anatomy. Third Edition. © Thieme 2016. Illustrations by Markus Voll and Karl Wesker.)
Fig. 1.3 Midsagittal section of adult brain showing the right hemisphere. (Reproduced with permission from Gilroy AM, MacPherson BR. Atlas of Anatomy. Third Edition. © Thieme 2016. Illustrations by Markus Voll and Karl Wesker.)
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