Introduction to the Central Nervous System

Learning Objectives

  • Name the major divisions of the central nervous system
  • Describe the growth and differentiation of the neural tube
  • Relate the different stages of development to the adult structures of the central nervous system
  • Explain the expansion of the ventricular system of the adult brain from the central canal of the neural tube
  • Describe the connections of the diencephalon and cerebellum on the basis of patterns of embryonic development
  • Describe the vessels that supply the CNS with blood
  • Name the components of the ventricular system and the regions of the brain in which each is located
  • Explain the production of cerebrospinal fluid and its flow through the ventricles
  • Explain how a disruption in circulation would result in a stroke
  • Describe the organization of the brain and spinal cord
  • Recognize the anatomical structures and functions of each brain division
  • Distinguish the major functions of the nervous system: sensation, integration, and response
  • List the sequence of events in a simple sensory receptor–motor response pathway
  • Compare different descending pathways, both by structure and function.
  • Describe the pathways that sensory systems follow into the central nervous system
  • Differentiate between the major ascending pathways in the spinal cord
  • Describe the pathway of somatosensory input from the face and compare it to the ascending pathways in the spinal cord
  • Identify the different categories of reflexes
  • Describe the signaling pathways of the four types of somatic reflexes
This photo shows a person playing foosball. The person has had both of their lower arms amputated. The left arm was replaced with a replica of a human hand and the right arm was replaced with a manipulator that resembles a pair of tongs.

Figure 1. Robotic Arms Playing Foosball As the neural circuitry of the nervous system has become more fully understood and robotics more sophisticated, it is now possible to integrate technology with the body and restore abilities following traumatic events. At some point in the future, will this type of technology lead to the ability to augment our nervous systems? (credit: U.S. Army/Wikimedia Commons)

The nervous system is a very complex organ system. In Peter D. Kramer’s book Listening to Prozac, a pharmaceutical researcher is quoted as saying, “If the human brain were simple enough for us to understand, we would be too simple to understand it” (1994). That quote is from the early 1990s; in the two decades since, progress has continued at an amazing rate within the scientific disciplines of neuroscience. It is an interesting conundrum to consider that the complexity of the nervous system may be too complex for it (that is, for us) to completely unravel. But our current level of understanding is probably nowhere close to that limit.

One easy way to begin to understand the structure of the nervous system is to start with the large divisions and work through to a more in-depth understanding. In the previous chapter, the finer details of the organization of the nervous system and nervous tissue were explained. The focus of this chapter is on the central nervous system, both its structure and its function.