Parts of the body idioms: skin and bone

All skin and bones - extremely thin. (She never puts on any weight whatever she eats. She's a real bean pole. Nothing but skin and bones.)
by the skin of your teeth- To only just manage to do something.(I caught that train by the skin of my teeth. They were already closing the gates when I rushed through.)
jump out of your skin - you are saying how much it surprised or shocked you ( I almost jumped out of my skin when the gun went off. It was such a loud bang.)

save your own skin - to save yourself from something unpleasant or dangerous ( When I heard that the police had started arresting the demonstrators, my first instinct was to save my own skin and get away as quickly as possible.)
get under your skin - something really irritates or annoys you ( I know you don't get on very well with Jamie - you always seem to be arguing - but don't let him get under your skin. )
it's no skin off my nose - it doesn't matter to you at all if something happens (It's no skin off my nose if Laura decides not to come. I couldn't care less! )