The transversus abdominis is the deepest of the abdominal muscles. Its fibers run horizontally and wrap around the waist from the vertebral column to the linea alba; it also joins the internal and external oblique muscles at the abdominal fascia, a sturdy sheath of connective tissue terminating anteriorly at the linea alba and lying superficial to the rectus abdominis. Because it lies deep to the rectus abdominis and the external and internal obliques, the transversus abdominis can be difficult to locate. 

A unique muscle in that it has no true action, the transversus abdominis is instead defined by its function of increasing intra-abdominal pressure. Contraction of the transversus abdominis compresses the organs and contents of the abdominal cavity; the resulting increase in pressure within the abdominal cavity serves three functions. First, it assists with expulsion of air during forced exhalation. Second, it assists with expulsion of abdominal contents such as urine and feces, or stomach contents during vomiting. Third, and most importantly to human movement, it supports and stabilizes the lumbar spine. This last function earns the transversus abdominis the nickname “anatomical weight belt,” as a strong, functional transversus abdominis serves the same purpose as the thick belts worn to prevent injury when lifting heavy objects.

Common postural deviations, such as lumbar lordosis and anterior pelvic tilt, can inhibit the activity of the transversus abdominis. Resolving these deviations by lengthening the erector spinae muscles, quadratus lumborum, and hip flexors provides a good start, but locating and stimulating activity in the transversus abdominis is essential to normalizing trunk posture and improving lumbar stability. 

Transversus Abdominis 

Attachments

•
Origin: Internal surfaces of ribs 7–12

•
Insertion: Abdominal aponeurosis

Actions

•
Compresses and supports abdominal organs

•
Assists with exhalation

Innervation

• T7–12, L1

•
Lower intercostal, iliohypogastric, and ilioinguinal nerves

Palpating the Transversus Abdominis

Positioning: client supine.

1.
Standing at the client’s side, face the abdomen and locate the most lateral edge of the iliac crest with the palms of both hands, one on each side.

2.
Slide hands superiorly, into the space between the iliac crest and inferior edge of the rib cage.  

3.
With your palms, locate the horizontal fibers of the transversus abdominis as it wraps around the waist.

4.

Have the client gently exhale while “hissing like a snake” to activate the muscle and ensure proper location.

Client Homework—
Transversus Abdominis Activation

1.
Lie, sit, or stand comfortably with the palm of each hand pressed against your lower belly.

2.

Gently press against your belly as you exhale slowly through your teeth, hissing like a snake.

3.
Keep your belly muscles tight as you
fully exhale.

4.
See if you can tighten the muscles without hissing and while breathing normally.

5.
Practice tightening the muscles in different positions, and during activities like lifting or reaching.

Editor’s note: The Client Homework element in Functional Anatomy is intended as a take-home resource for clients experiencing issues with the profiled muscle. The stretches identified in Functional Anatomy should not be performed within massage sessions or progressed by massage therapists, in order to comply with state laws and maintain scope of practice.

Christy Cael is a licensed massage therapist and certified strength and conditioning specialist. Her private practice focuses on injury treatment, biomechanical analysis, craniosacral therapy, and massage for clients with neurological issues. She is the author of Functional Anatomy: Musculoskeletal Anatomy, Kinesiology, and Palpation for Manual Therapists (Lippincott Williams & Wilkins, 2009). Contact her at functionalbook@hotmail.com.

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