Transverse abdominal muscle

Muscle layer of the anterior and lateral abdominal wall

Illustration of trunk muscles, including the transverse abdominal muscle

Transversus abdominis muscle

Transverse section through the middle of the first lumbar vertebra, showing the relations of the pancreas. (Transversus abdominis labeled at bottom left.)

Diagram of a transverse section through the anterior abdomino-thoracic wall, showing the transversus abdominis.

The transversus abdominis is shown in this diagram of the muscles of the trunk.

The transversus abdominis is visible in this diagram of the muscles of the trunk.

The transversus abdominis is shown in this diagram of the muscles of the trunk.

The transversus abdominis is shown in this diagram of the muscles of the trunk.

The transversus abdominis is shown in this diagram of the muscles of the trunk.

The transverse abdominal muscle (musculus transversus abdominis), also known as the transversus abdominis, is a muscle layer of the anterior and lateral abdominal wall which is deep to the internal oblique muscle. It is a major component of the core muscles and plays a crucial role in maintaining abdominal tension and stability.

Structure

The transverse abdominal muscle is the innermost of the flat muscles of the abdomen. It arises from the lateral third of the inguinal ligament, the anterior two-thirds of the inner lip of the iliac crest, the thoracolumbar fascia, and the inner surfaces of the lower six costal cartilages. The fibers run horizontally and insert into the linea alba, the pubic crest, and the pectineal line of the pubis.

Function

The primary function of the transversus abdominis is to compress the abdominal contents. This action is crucial for maintaining intra-abdominal pressure, which is important for stabilizing the spine and pelvis during movement. It also plays a role in forced expiration and acts as a stabilizer for the lumbar spine during lifting and other activities.

Innervation

The transversus abdominis is innervated by the lower six thoracoabdominal nerves (T7-T11) and the first lumbar nerve (L1). The iliohypogastric and ilioinguinal nerves, which are branches of the lumbar plexus, also contribute to its innervation.

Clinical significance

Weakness or dysfunction of the transversus abdominis can lead to lower back pain and instability. Strengthening this muscle is often a focus in rehabilitation programs for individuals with back pain or core instability. Techniques such as the "drawing-in maneuver" are used to activate the transversus abdominis during exercises.

Related pages

• Rectus abdominis muscle
• Internal oblique muscle
• External oblique muscle
• Abdominal muscles