Spinal Animal

in physiological studies, an animal, usually a frog, dog, or cat, whose spinal cord has been transected, thus cutting off communication with the brain. As a result of the severance of the spinal cord, the parts of an animal’s body innervated by fibers extending from segments of the spinal cord situated below the transected portion can function reflexively only in response to impulses reaching these segments. A spinal animal can live a long time if the transection is made below the fifth or sixth cervical segments, that is, if it does not cause the nerve cells of the spinal cord that innervate the respiratory musculature to become disconnected from the respiratory center. The examination of reflexes in a spinal animal is important in studying the general mechanisms of reflex activity in vertebrate animals and in understanding the phenomena that follow injury to the spinal cord in man.