Causes of lock jaw
type of bacteria called Clostridium tetani causes tetanus. The spores of these bacteria are found in soil, dust and manure. The spores enter your body through breaks in your skin. Once the spores enter your body, they become active bacteria. The bacteria spread in your body and make a poison called tetanus toxin. This poison blocks the nerve signals from your spinal cord to your muscles. This causes severe muscle spasms. The spasms can be so strong they tear your muscles or cause spinal fractures. Tetanus bacteria most commonly enter your body through deep cuts or puncture wounds. This includes stepping on a rusty nail or getting a wood or metal splinter. Other ways the bacteria can enter your body include: Burns. Exposed broken bones (compound fractures). Crush injuries. Insect bites and dog bites. Using infected syringes. Surgical procedures. Dental infections. Tetanus isn’t spread from person to person.