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Transversus Abdominis: Function, Origin & Insertion

Instructor: Kaitlin Baker

Kaitlin has taught nursing students and has a master's degree in nursing leaderhsip, as well as a bachelor's degree in English literature.

This lesson will describe the transversus abdominis: an abdominal muscle which works to stabilize the lower back and pelvis and support the abdominal wall. In this lesson, you will learn about the muscle's function, origin, and insertion.

Transversus Abdominis: The ''Corset Muscles''

In Victorian times, many women wore corsets to draw in their waists and make them appear smaller. In modern times, many people do endless crunches and abdominal exercises to obtain that desired ''6-pack.'' In both eras, the same muscles are involved: the transversus abdominis (also called transverse abdominis or TA). Located on each side on the torso, these muscles are actually referred to as the ''corset muscles'' in Pilates exercises, and they play a key role in strengthening and stabilizing the core.

The Corset Muscles

Corsets to Crunches: What does the TA Do?

Located on the front and sides of the abdomen, and deeper than all the other abdominal muscles, the transverse abdominis (TA) does many jobs and is critical for the body's overall function and stability. There is one TA muscle on each side of the body, and each wraps in a horizontal direction from back to front, where they are connected by a fascial sheet (thin strip of fibrous, connective tissue) which allows the two muscles to act as one.

A cut-away view of the TA

The TA muscles support the abdominal wall, also known as the core, and hold the internal organs in place. Contraction of these muscles is done voluntarily, meaning that you can control it yourself, and it has a corset-like effect on your abdomen by flattening and narrowing the muscles which pull in your waist.

These muscles support breathing by helping to pull the abdomen inward, and in that way force air out of the lungs to make room for a new breath of fresh air. These muscles also raise the intra-abdominal pressure which is necessary for functions like urination, defection (having a bowel movement), vomiting, and vaginal childbirth. Other examples of everyday use of this muscle include anything that involves deep breathing or having to use forced exhalation, like playing a wind instrument, blowing up balloons, or moving furniture.

Transverse Abdominis

Together with the obliques (muscles on the sides of the torso), the transverse abdominis muscles also support the bones of the spine when the body is in a squatting or bent-over position. While none of the abdominal muscles actually attach to the spine, the fascia that connects the TA muscles does. The stability this provides helps with those squats and deadlifts at the gym! The TA muscles also collaborate with the obliques and the rectus abdominis (upper abdomen) muscles to hold the belly flat when needed (during crunches and plank exercises, for example.

The Abdominal Muscles

Origin and Insertion of the TA

All voluntary muscles have an origin and an insertion, and the TA is no exception. In most cases, one end of the muscle (the origin) is still, while the other end (the insertion) moves.

TA Origin

The origin of a muscle is the point at which is attaches to a bone which is fixed, or unmoving. The origin is usually the end that is closer to the center of the body, a direction known as proximal. For example, the ankle is distal to the knee (meaning that it is further away from the center of the body than the knee is), and the wrist is distal to the elbow.

The transverse abdominis originates on the following structures:

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