Final answer:
The left hemisphere controls the right side of the body and the right hemisphere controls the left side due to the organization of the nervous system and brain lateralization, which includes crossing of the corticospinal tract and ascending tracts, and the role of the corpus callosum in hemispheric communication.
Step-by-step explanation:
Anatomical Basis for Body Control by Opposite Brain Hemispheres
The left hemisphere of the brain controls the right side of the body and vice versa due to the way the nervous system is organized. This is related to the concept of brain lateralization. In most people, language functions are localized to the left hemisphere, which is also responsible for controlling movements and receiving sensory input from the right side of the body. This connection happens through the corticospinal tract and the ascending tracts of the spinal cord. Cross-communication between hemispheres is facilitated by the corpus callosum, supporting coordinated activities and sensory integration.
Further illustrating this, a verbal command to move the right arm is processed in the left brain but also must interact with the right brain to coordinate with the left arm through the corpus callosum. Additionally, sensory perceptions by the left hand are sent to the right brain and must be transmitted back to the language-dominant left hemisphere for a verbal response. This is a testament to the complex interaction between the hemispheres to manage opposite sides of the body.
Research on split brain patients, individuals who have undergone a surgical division of the corpus callosum to treat intractable epilepsy, supports these observations by demonstrating the specialized functions of each cerebral hemisphere and their collaboration through inter-hemispheric connections.