The caudal medulla looks somewhat similar to the spinal cord, but this similarity seems to disappear at more rostral levels of the brainstem. One of the complicating factors is the arrangement of the tracts and nuclei associated with cranial nerves…
The spinal cord continues rostrally into the brainstem ( Fig. 11.1 ), which performs spinal cord–like functions for the head. The brainstem contains the lower motor neurons for the muscles of the head and does the initial processing of general…
The spinal cord is the traditional starting point for a detailed consideration of the central nervous system (CNS). It is a uniformly organized part of the CNS and one of the simplest (in a relative sense), but many principles of…
The ongoing activity and output of the central nervous system (CNS) are greatly influenced, and sometimes more or less determined, by incoming sensory information. An example is our constant awareness of the position of our limbs in space and the…
Early in the last century, Ramón y Cajal and others used the Golgi stain to demonstrate that the nervous system is a collection of individual neurons (e.g., see Fig. 1.16A ) rather than a vast syncytial network, as some had…
We depend on our brains to process and convey huge quantities of information rapidly and reliably. As a biological system, the brain must do this using neurons and their axons and synapses rather than wires and transistors. This makes the…
Turtles can walk around for hours with no oxygen supply to their brains. In contrast, our brains are absolutely dependent on a continuous supply of well-oxygenated blood. After just 10 seconds of brain ischemia, we lose consciousness. After 20 seconds,…
The cavity of the embryonic neural tube develops into a continuous, fluid-filled system of ventricles lined with ependymal cells; each division of the central nervous system (CNS) contains a portion of this ventricular system. Cerebrospinal fluid (CSF) is formed within…
Living brain is soft and mushy, despite the network of cytoskeletal proteins contained in neurons and glial cells. Without support of some kind, the central nervous system (CNS) would be unable to maintain its shape, particularly as we walk and…
The human central nervous system (CNS) is composed of the brain and spinal cord. This chapter briefly discusses the major surface and internal structures of the brain (summarized in Fig. 3.26 ) and, together with the following six chapters, lays…