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Unlike the CNS, the PNS is not protected by the vertebral column and skull, or by the blood–brain barrier, which leaves it exposed to toxins. [3] The peripheral nervous system can be divided into the somatic nervous system and the visceral nervous system. Each of these have a sensory and a motor division.
The human nervous system consists of two main parts: the central nervous system (CNS) and the peripheral nervous system (PNS). The CNS contains the brain and spinal cord. The PNS consists mainly of nerves, which are long fibers that connect the CNS to every other part of the body.
The CNS is enclosed and protected by the meninges, a three-layered system of membranes, including a tough, leathery outer layer called the dura mater. The brain is also protected by the skull, and the spinal cord by the vertebrae. The peripheral nervous system (PNS) is a collective term for the nervous system structures that do not lie within ...
The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain and spinal cord.The CNS is so named because the brain integrates the received information and coordinates and influences the activity of all parts of the bodies of bilaterally symmetric and triploblastic animals—that is, all multicellular animals except sponges and diploblasts.
The cranial nerves are considered components of the peripheral nervous system (PNS), [3] although on a structural level the olfactory (I), optic (II), and trigeminal (V) nerves are more accurately considered part of the central nervous system (CNS). [4] The cranial nerves are in contrast to spinal nerves, which emerge from segments of the ...
Neuroregeneration differs between the peripheral nervous system (PNS) and the central nervous system (CNS) by the functional mechanisms involved, especially in the extent and speed of repair. When an axon is damaged, the distal segment undergoes Wallerian degeneration , losing its myelin sheath.
A nervous system tumor is a tumor that arises within the nervous system, either the central nervous system (CNS) or the peripheral nervous system (PNS). [1] [2] Nervous system primary tumors include various types of brain tumor and spinal tumors, such as gliomas, and meningiomas (of the CNS), and schwannomas (of the PNS) and can be either benign or malignant.
Central nervous system tumors are the most common forms of pediatric cancer. Brain tumors are the most frequent and have the highest mortality. [4] Some disorders, such as substance addiction, autism, and ADHD may be regarded as CNS disorders, though the classifications are not without dispute.