The |serratus anterior| (serratus magnus) is a large quadrilateral muscle that curves along the |rib| cage. The muscle is divided into several bundles, each of which extends along the side and upper border of each |rib|. The muscle is divided into two portions, and upper and lower portion. The upper portion lies along the upper side of the |rib| cage and the armpit. The lower portion consists of five or six pointed digitations which create a fan-shaped mass extending from the |scapula| (shoulder blade). This muscle is used everytime you reach out or push forward with your arms. It also helps raise the |shoulder joint| when lifting your arm above your head.
