Final answer:
Hemiplegia affects one side of the body, paraplegia affects both legs and the trunk but not the arms, and quadriplegia affects all four limbs and the trunk. A spinal cord hemisection may result in patients feeling pain but not fine touch or proprioception on the paralyzed leg due to different pathways for these sensations.
Step-by-step explanation:
Spinal cord injuries can lead to various forms of paralysis, which differ based on the extent and location of the injury. Hemiplegia refers to paralysis that affects only one side of the body, usually one arm and one leg on the same side. It often results from damage to part of the brain due to stroke or traumatic injury affecting motor pathways.
Paraplegia is a form of paralysis affecting the trunk, legs, and pelvic organs but not the arms, which is generally caused by injury to the spinal cord in the thoracic or lumbar region. People with paraplegia have their upper extremity functions preserved.
Quadriplegia, also known as tetraplegia, involves paralysis of both arms and legs, typically resulting from an injury to the cervical spine. This form of paralysis affects the trunk, legs, arms, and pelvic organs.
Regarding sensory deficits following a spinal cord hemisection, sensory discrimination can help pinpoint the level of spinal cord damage. Patients with a hemisection of the spinal cord may acknowledge painful stimuli on the paralyzed leg due to the spinothalamic pathway that crosses immediately upon entering the spinal cord. However, they would not perceive fine touch or proprioceptive sensations due to damage to the ipsilateral dorsal column pathway, which ascends along the side of the sensation.