What best describes quadriplegia?

Quadriplegia, also known as tetraplegia, is defined as paralysis affecting all four limbs—both the arms and the legs. This condition typically results from injury or damage to the spinal cord at a level that impacts the transmission of signals between the brain and the entire body, particularly below the point of injury. As a result, individuals with quadriplegia may experience varying degrees of loss in motor functions and sensations in the upper and lower extremities.

Understanding this definition clarifies why the other options do not properly define quadriplegia. Paralysis of the lower limbs refers specifically to paraplegia, which only affects the legs, while loss of sensation in all limbs can occur in various neurological conditions and does not imply complete paralysis. Muscle weakness in the upper body suggests a decline in strength rather than a total lack of function, which is not characteristic of quadriplegia. Therefore, the option that correctly describes quadriplegia is the one that encompasses the paralysis of all four extremities.