An involuntary contraction of the muscles of the abdominal wall: Abdominal reflexes occur when the overlying skin is stimulated by stroking or scratching or by tapping neighboring bony structures.

A lack of these reflexes indicates damage to the pyramidal tract or the projection neurones in the cerebral cortex and the hippocampus of the brain or two groups of nerve fibers that participate in the complex and delicate coordination of motor activity arising in the brain and passing down through the spinal cord to motor cells.