In 1817 James Parkinson, an English country physician, published a brief monograph entitled “An Essay on the Shaking Palsy,” in which he described the symptoms of several individuals who had the disease that now bears his name. Patients with Parkinson's…
Each of us has fewer than a million motor neurons with which to control muscles. Without them, we would be completely unable to interact with the outside world. With them, however, we are capable of an enormous range of complex…
It is clear from everyday experience that humans are a visually oriented species. Although it is arguable which of our senses is most important, loss of vision certainly has a greater impact on humans than loss of, for example, olfaction…
The diencephalon, mostly hidden from view between the cerebral hemispheres ( Fig. 16.1A ), constitutes only about 2% of the central nervous system (CNS) by weight. Nevertheless, it has widespread and important connections, and the great majority of sensory, motor,…
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Hearing and balance are very different senses functionally, but they begin peripherally in very similar ways. The eighth cranial nerve carries two special sensory components, one in a cochlear division and one in a vestibular division. Both divisions innervate elaborate…
Dating back to their origins in some primordial sea, living cells have shared an ability to respond to chemicals, at a minimum detecting and absorbing nutrients. Neurons detect chemicals at synapses, but some cells in or closely associated with the…
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…