Rectus Abdominis Muscle: The rectus abdominis muscle is a long strap muscle that continues the entire length of the anterior abdominal wall. It is broader above and lies close to the midline, being separated from its associated by the linea alba. It arises by two heads from the anterior aspect of the symphysis pubis and the pubic crest and it inserts into the 5th, 6th, and 7th costal cartilages and xiphoid process. Each rectus abdominis muscle is split into three distinct segments by three transverse fibrous intersections, one at the umbilicus, one at the level of the xiphoid process and one halfway between the two.
The rectus abdominis muscle is inserted between the aponeuroses of the external and internal obliques and transversus abdominis muscles that form the rectus sheath.
Nerve Supply of the Rectus Abdominis
The lower six thoracic nerves.
Function of the Rectus Abdominis
The rectus abdominis muscle is an essential postural muscle. Besides a fixed pelvis, contraction results in flexion of the lumbar spine. While the ribcage is fixed contraction effects in a posterior pelvic tilt. It additionally plays a significant role in forced expiration and in increasing intra-abdominal pressure.