Medical Focus on CNS


Spinal cord and meninges

Spinal Cord and Spinal nerves

Spinal cord injuries may result from accidents or other trauma. The cord may be completely cut across (transection) or only partially severed (partial section). The location and extent of the damage produce a variety of effects, depending on the partial or complete stoppage of impulses passing up and down the spinal cord. If the spinal cord is completely transected, no sensations or somatic motor impulses traveling in the cord will be able to pass the point where the cord is cut. If the injury is between the first thoracic vertebra (T1) and the second lumbar vertebra (L2), paralysis of the lower body and legs occurs. This condition is known as paraplegia. If the injury is between the fourth cervical vertebra (C4) and the first thoracic vertebra (T1), the entire body and all four limbs are usually affected. This condition is called quadriplegia. If the injury is a unilateral hemisection (half cut), motor loss will occur on the same side as the injury because motor neuron crossover occurs in the medulla oblongata. At the same time, loss of sensation will vary, and the pattern and type of such loss can be analyzed to locate the lesion.


Lateral view of brain

Functional areas of cerebral cortex

Current research indicates that the right side of the cerebral hemisphere handles emotion and holistic thoughts (“the big picture”), and is more intuitive than the left side. The left side appears to handle language, math, and music, and is said to be the “rational” side of the brain. Brain imaging techniques illustrate more activity in the right hemisphere for artists and navigators. The motor cortex, cerebellum, and basal ganglia are more organized in dancers and other athletes, while individuals who work with people, such as psychologists, use their limbic system more efficiently. From ages 7–10 years to adulthood, males are observed to excel at visual-spatial skills, whereas females during the same time period are more generalists. In general, males use the left hemisphere (including Broca’s area) more while females use both hemispheres equally. This explains why males tend to have more speaking difficulties after a stroke affects the brain’s left side than females in the same situation. Females have an analogous region to Broca’s area in their right side that can take over speech functions.

Adapted from Understanding Human Anatomy and Physiology

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