origin: first and second costal cartilage; sternum
between first and fourth costal cartilages
insertion: pubic tubercle
nerve: ventral rami of lumbar nerves 1 to 3
action: abdominal press, flexion of trunk
origin: pubic tubercle, pubic symphysis,
and pubic crest
insertion: costal cartilages of ribs 5 to 7;
nerve: anterior rami of inferior thoracic spinal
nerves (T7 to T12)
action: abdominal press, flexion of vertebral
column (trunk flexion)
The rectus abdominis is often incorrectly known as the six pack muscle. Actually it is an eight pack muscle. The four divisions on each side result from three tendinous intersections of this muscle. The muscle is enclosed within the aponeurosis of the internal abdominal oblique, much like sandwich meat in a pita pocket. The three aponeuroses plus the rectus abdominis is referred to as the rectus sheath. Functionally it is of importance because it participates in the abdominal press. It is sometimes used in breast reconstruction surgery. The rectus abdominis in the cat is sometimes referred to as the bacon muscle by Dr. J's students. This is because it looks suspiciously like bacon. In fact, Dr. J suspects that this may be where bacon comes from. A few students refer to it as one of the Oscar Myer muscles, the other being rectus femoris which looks a lot like a cocktail wiener.
by William C. Johnson II
ALL RIGHTS RESERVED!