security threat meaning, security threat definition | English Cobuild dictionary. security. 1 n-uncount Security refers to all the measures that are taken to protect a place, or to ensure that only people with permission enter it or leave it.
A muscle expands when it relaxes. The muscles in our bodies are attached to bones. They help the bones move, much like strings help a puppet move. But muscles can pull in only one direction. They cannot push.Each bone is usually attached to a pair of muscles.ones and muscles work like  ropes and levers. The muscles can only pull against the bone not  push it. So to bend your arm at the elbow, the â¦ bicep pulls the  lower arm up. To streighten your arm, the tricep pulls the lower  arm back out. the muscles have to work in pairs opposite each other  to make movement.
The tendons are attached so well that when you contract one of your muscles, the tendon and bone move along with it. Skeletal muscles come in many different sizes and shapes to allow them to do many types of jobs. Some of your biggest and most powerful muscles are in your back, near your spine. These muscles help keep you upright and standing tall. They also give your body the power it needs to lift and push things.