Six Pack Abs Anatomy

The Anatomy of Six Packs and Washboard Abs

Rectus Abdominis – The Abdominal Muscles Behind Six Pack Abs

Before embarking on diets and workouts to develop the much sought after six packs abs, learning a little about the basic, underlying anatomy might help. Six pack or washboard abs are the result of toning a single pair of abdominal muscles – the rectus abdominis muscles. Here’s a look at the location and function of the rectus muscles and why working on them results in six packs.

Rectus Abdominis – The Six Pack Muscles

The rectus abdominis is a pair of long and flat muscles that, along with the external oblique, the internal oblique and the transverse abdominal muscles, form the abdominal wall. This pair of muscles lies on either side of the midline running from the ribcage above to the pelvic bone below.

Each of them is enclosed in a ‘rectus sheath’, a fibrous covering formed by the aponeuroses or white, fibrous portions of the other abdominal muscles. The front of this muscle has three tendinous intersections to help attach it to its fibrous covering. These are horizontal lines of tendon on the surface of the muscle so that when it contracts, the muscular parts stand out in packets in between these intersections.

The first of the three intersections lies at the level of the lower border of the breast bone, the third at the level of the umbilicus or the belly button and the second midway between the two.

The edge of the muscle is also well defined, this being the place where the fibrous portions of the other abdominal muscles split to enclose the rectus abdominis, forming the rectus sheath. In the midline the rectus sheaths of both sides fuse to form the linea alba or the white line. Together, these lines define the shape of this muscle and help give the six pack look when it is contracted.

The Rectus Abdominis, Abdominal Fat and Abdominal Crunch

The rectus is attached to the 5th, 6th and 7th ribs above and the pelvic bone below. So when it contracts, it helps flex or bend the vertebral column forwards. This is why the muscle is best defined when a person lies flat and tries to raise the head and shoulders from the floor.

This is also why abdominal crunches and other exercises involving flexing the spine are used to strengthen the rectus muscles. These muscles also help in expiration.

In the abdominal wall, the superficial fascia or the tissue layer just below the skin contains a variable amount of fat. There is usually greater deposition of fat in the lower abdomen, around and below the level of the umbilicus. This fat layer easily hides the rectus abdominis muscles. This is why losing abdominal fat is also vital to gaining six pack abs.

With proper diet and abdominal workout, the rectus abdominis, along with the other abdominal muscles, can be strengthened to achieve six pack abs.

Photo by MandoBarista

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