An interactive online guide to the neurologic examination. The Precise Neurological Exam. Neurologic Exam Videos and Descriptions: An Anatomical Approach. The 12 Cranial Nerves. University - Cranial Nerves. Table of Contents, Section 2: Neuroscience Online: An Electronic Textbook for the Neurosciences. Overview of the Nervous System (Section 2, Chapter 1) Neuroscience Online: An Electronic Textbook for the Neurosciences. The human nervous system is divided into the central nervous system (CNS) and the peripheral nervous system (PNS).
The CNS, in turn, is divided into the brain and the spinal cord, which lie in the cranial cavity of the skull and the vertebral canal, respectively. The CNS and the PNS, acting in concert, integrate sensory information and control motor and cognitive functions. 1.1 The Central Nervous System (CNS) The adult human brain weighs between 1,200 to 1,500 g and contains about one trillion cells. It occupies a volume of about 1400 cc - approximately 2% of the total body weight, and receives 20% of the blood, oxygen, and calories supplied to the body.