first rib

(redirected from Left first rib)

first rib

the highest rib of the thoracic cage. It moves about the axis of its neck, raising and lowering the sternum. First rib movement during quiet breathing is negligible, but under conditions of stress it can increase the anteroposterior diameter of the chest.
References in periodicals archive ?
A radiographic examination showed an apparent fracture line with no callus formation in the middle of the left first rib (Figure 1A).