Rectus Abdominis Muscle

Rectus is the Latin word for straight.
Abdominis of course, refers to the abdomen.
The rectus abdominis, specifically, is the straight abdominal muscle that we’re all familiar with.

Where does the rectus abdominis muscle attach?

It’s important to recognize that the origin and insertion of the rectus abdominis can change depending on the movement.

Because of the long area it covers and the strength necessary, it’s compartmentalized into little packets. This is what we refer to as the six pack. Technically there are four compartments on each side.

Origin

Generally, it’s considered to originate on the pubic symphysis.

Insertion

It inserts onto the costal cartilages 5, 6, & 7 and the xiphoid process.

What actions does the rectus abdominis muscle do?

The rectus abdominis acts to flex the trunk and compress the abdominal contents.
In the case of these abdominal muscles, stabilization is a key function.

Poses where the rectus abdominis muscle contracts:

In a posture such as navasana, we see that all of the abdominals will be doing an isometric contraction in order to help stabilize the trunk.

A posture such as parighasana requires lateral flexion of the spine. So as we lean over our left leg, the left side is contracting.

Poses where the rectus abdominis muscle is lengthened:

In a posture such as urdhva dhanurasana we are lengthening all of the abdominal muscles as the rib cage and the pelvis move apart.

In a posture such as parighasana, when we lean over our left leg, the right side of the body is lengthening.

Trigger points