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.
Relationship of skeletal muscles to bones. - Muscles are attached to bones by tendons known as the origins and insertions. - Skeletal muscles produce movements by pulling on bones. - Bones serve as levers, and joints act as fulcrums for the levers. - Muscles that move a body part often do not cover the moving part.