In addition to being the major site of crossover for nerve tracts running to and from the brain, the medulla is the seat of several pairs of nerves for organs of the chest and abdomen, for movements of the shoulder and head, for swallowing, salivation, and taste, and for hearing and equilibrium.Īt the top of the brainstem is the pons-literally, a bridge-between the lower brainstem and the midbrain. Thus, the left brain controls movement of the right side of the body, and the right brain controls movement of the left side. Through the medulla, at the lower end of the brainstem, pass all the nerves running between the spinal cord and the brain in the pyramids of the medulla, many of these nerve tracts for motor signals cross over from one side of the body to the other. This region is also an important junction for the control of deliberate movement. The brainstem, at the top of the spinal cord, controls breathing, the beating of the heart, and the diameter of blood vessels. The hindbrain contains several structures that regulate autonomic functions, which are essential to survival and not under our conscious control.
#PARTS OF THE BRAIN WORKSHEET ANSWERS SERIES#
The human brain actually has its beginnings, in the four-week-old embryo, as a simple series of bulges at one end of the neural tube. In the growth of the individual embryo, as well as in evolutionary history, the brain develops roughly from the base of the skull up and outward. Indeed, in strictly biological terms, these structures can claim priority over the cerebral cortex.
But underneath this layer reside many other specialized structures that are essential for movement, consciousness, sexuality, the action of our five senses, and more-all equally valuable to human existence. The cortex contains the physical structures responsible for most of what we call ''brainwork": cognition, mental imagery, the highly sophisticated processing of visual information, and the ability to produce and understand language. The preponderance of the cerebral cortex (which, with its supporting structures, makes up approximately 80 percent of the brain's total volume) is actually a recent development in the course of evolution. This schematic image refers mainly to the cerebral cortex, the outermost layer that overlies most of the other brain structures like a fantastically wrinkled tissue wrapped around an orange. We do not experience our brain as an assembly of physical structures (nor would we wish to, perhaps) if we envision it at all, we are likely to see it as a large, rounded walnut, grayish in color. Outside the specialized world of neuroanatomy and for most of the uses of daily life, the brain is more or less an abstract entity.
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