External abdominal oblique muscle

The external abdominal oblique muscle is the most superficial of the lateral abdominal muscles. It originates from the lateral surfaces of the ribs (varies by species, typically from the last several ribs) and inserts onto the linea alba and pelvic structures (pubic symphyses and xiphoid process ) via a broad aponeurosis.

The obliquus externus abdominis is divided in two different parts (not listed in the Vth NAV) in carnivores:

• A costal part (Obliquus Externus Abdominis (Pars Costalis))

  • Origin: From the middle parts of the fourth to twelfth ribs and the adjacent trunk fascia.

  • Insertion: Pubic symphyses and xiphoid process via the linea alba.

  • 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: Lateral branches of the last eight or nine intercostales and the lateral branches of the costoabdominalis, iliohypogastricus, and ilioinguinalis.

  • A lumbar part (Obliquus Externus Abdominis (Pars Lumbalis))

• Origin: Last rib.

  • Insertion: Into twelfth rib.

  • 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: Lateral branches of the last eight or nine intercostales and the lateral branches of the costoabdominalis, iliohypogastricus, and ilioinguinalis.