Pectoralis minor - Musculus pectoralis minor
Origin: 3rd to 5th ribs, near their costal cartilages
Insertion: Medial border and superior surface of the coracoid process of the scapula
Artery: Pectoral branch of the thoracoacromial trunk
Nerve: Medial pectoral nerves (C8, T1)
Action: Stabilizes the scapula by drawing it inferiorly and anteriorly against the thoracic wall
The Pectoralis minor is a thin, triangular muscle, situated at the upper part of the thorax, beneath the Pectoralis major. It arises from the upper margins and outer surfaces of the third, fourth, and fifth ribs, near their cartilage and from the aponeuroses covering the Intercostalis; the fibers pass upward and lateralward and converge to form a flat tendon, which is inserted into the medial border and upper surface of the coracoid process of the scapula.
Variations.—Origin from second, third and fourth or fifth ribs. The tendon of insertion may extend over the coracoid process to the greater tubercle. May be split into several parts. Absence rare. Pectoralis minimus, first rib-cartilage to coracoid process. Rare
This definition incorporates text from a public domain edition of Gray's Anatomy (20th U.S. edition of Gray's Anatomy of the Human Body, published in 1918 – from http://www.bartleby.com/107/).