The serratus anterior lies on the outer surface of the ribs at the side and is covered by the scapula at the rear and the pectoralis major in the front.
Origin
The serratus anterior originates on the outer surfaces of the upper eight or nine ribs at the side of the chest in between the attachments of the external oblique.
Insertion
It inserts on the anterior surface of the medial border of the scapula.
Function
The serratus anterior is involved in upward rotation of the scapula and in abduction, that is, it helps pull the scapula to the sides away from the spine.