Origin: From the sternum and costal cartilage.
Insertion: Unites with the tendon of origin of the pectineus muscle and the prepubic tendon.
Action: Along with other abdominal muscles, compression of the abdominal viscera. This action, known as abdominal press, aids in such vital functions as expiration, urination, defecation, and parturition. Flexion of the vertebral column when fellow muscles contract. Lateral bending of the vertebral column.
Nerve: Medial branches of the intercostales and medial branches of the costoabdominalis, iliohypogstricus and ilioinguinalis.