Corpus: Transversus abdominis muscle
1. Definition
The transversus abdominis muscle is a skeletal muscle that is part of the lateral abdominal musculature.
2. Progression
2.1. Origin
The transversus abdominis muscle originates from several areas:
- The inner surfaces of the 7th to 10th costal cartilages and the 11th and 12th ribs
- The anterior layer (lamina anterior or profunda) of the thoracolumbar fascia
- The inner lip of the crista iliaca
- The anterior superior iliac spine
- The inguinal ligament
2.2. Attachment
The muscle fibers of the transversus abdominis muscle run transversely to insert at the linea alba. Its flat aponeurosis contributes to the formation of the rectus sheath.
2.2.1. Special features
The caudal fiber bundles of the transversus abdominis muscle, together with fibers from the obliquus internus abdominis muscle, form the cremaster muscle in men, which is associated with the spermatic cord. In women, these fiber bundles run within the round ligament of the uterus.
3. Innervation
The transversus abdominis muscle is innervated by the lower intercostal nerves as well as the ilioinguinal and iliohypogastric nerves.
4. Function
The transversus abdominis muscle serves to rotate the trunk to the same side when it contracts unilaterally. When both sides contract, the muscle compresses the abdominal organs, aiding in expiration and creating abdominal pressure, which is important for functions such as forced exhalation and the abdominal press.