Hypotonia is a medical term that describes decreased muscle tone. It is not the same as muscle weakness, although the two conditions can happen at the same time. Muscle tone is controlled by signals that travel from the brain to the nerves and tell the muscles to contract. Hypotonia can result from damage to the brain, spinal cord, nerves, or muscles. Infants with hypotonia may have a floppy quality or “rag doll” appearance because their arms and legs hang by their sides, and they have little or no head control. Other symptoms include problems with mobility and posture, breathing and speech difficulties, ligament and joint laxity, and poor reflexes. Hypotonia can be a condition on its own, called benign congenital hypotonia, or it can be indicative of other underlying medical conditions such as cerebral palsy, brain damage, muscular dystrophy, and genetic conditions like Down syndrome and Prader-Willi syndrome. Treatment begins with a thorough diagnostic evaluation, usually performed by a neurologist, which includes an assessment of motor and sensory skills, balance and coordination. Once the underlying cause of hypotonia is diagnosed, treatment can be tailored to the specific condition. Physical, occupational, and speech therapy can help improve muscle tone and coordination.