The serratus anterior is a part of the pectoral muscle that attaches to the surface of the lateral wall of the thorax, roughly above the lateral chest wall. The teeth of the serratus anterior begin at the lateral surface of ribs 1 to 9, then travel along the medial superior oblique of the chest wall, passing through the lateral and posterior portions of the thorax, and passing anteriorly over the scapula to end at the medial border of the scapula and the inferior angle of the scapula. When the scapula is pulled forward, the scapula is pressed against the thorax and the inferior angle of the scapula is rotated outward, which helps the shoulder to lift. When the scapula is immobilized, it helps the body to perform deep inhalation. The nerve innervating the scapula is the long thoracic nerve. When the long thoracic nerve is injured, it causes the spinal border and inferior angle of the scapula to buckle in a posteriorly outward direction, forming a winged scapula.