Tetanus, also called lockjaw, is a medical condition characterized by, a prolonged contraction of skeletal muscle fibers. The primary symptoms are caused by tetanospasmin, a neurotoxin produced by the Gram-positive, obligate anaerobic bacterium Clostridium tetani. Infection generally occurs through wound contamination, and often involves a cut or deep puncture wound. As the infection progresses, muscle spasms in the jaw develop, hence the name lockjaw. This is followed by difficulty in swallowing and general muscle stiffness and spasms in other parts of the body. Infection can be prevented by proper immunization and by post-exposure prophylaxis.

Source: Wikipedia.