Muscle
Transversus abdominis
Deep abdominal muscle supporting pressure and stability
High-yield
Abdominal compression is its central action. Its fiber arrangement is not identical at every level of the abdominal wall.
Overview
Transversus abdominis forms the deepest of the three lateral abdominal muscle layers. Much of its course is transverse, although lower fibers angle downward. Its aponeurosis carries tension toward the midline and contributes inferiorly to the pubic attachment complex.
Reference facts
- Origin
- Inner surfaces of costal cartilages 7–12, thoracolumbar fascia, iliac crest and lateral inguinal ligament.
- Insertion
- Linea alba, with inferior fibers reaching the pubic crest and pectineal region.
- Action
- Compresses the viscera and helps regulate intra-abdominal pressure during coordinated trunk activity.
- Innervation
- Lower thoracoabdominal nerves and subcostal nerve, with L1 contributions.
- Blood supply
- Segmental lower intercostal branches and the deep circumflex iliac artery supply the muscle.
Clinical correlation
The transversus aponeurosis and internal oblique can reinforce the medial posterior inguinal wall. Direct inguinal hernias involve weakness of that wall; they cannot be attributed solely to a defective conjoint tendon.
Frequently asked questions
What does the transversus abdominis do?
The transversus abdominis compresses the viscera and helps regulate intra-abdominal pressure during coordinated trunk activity.
What nerve innervates the transversus abdominis?
The transversus abdominis is innervated by the lower thoracoabdominal nerves and subcostal nerve, with L1 contributions.
Where does the transversus abdominis attach?
The transversus abdominis originates from the inner surfaces of costal cartilages 7–12, thoracolumbar fascia, iliac crest and lateral inguinal ligament and inserts on the linea alba, with inferior fibers reaching the pubic crest and pectineal region.
What is the blood supply of the transversus abdominis?
The transversus abdominis is supplied by the segmental lower intercostal branches and the deep circumflex iliac artery supply the muscle.