Corpus: Rectus sheath

The term rectus sheath refers to the sheath of the rectus abdominis muscle, which is formed by the aponeuroses of the other three abdominal muscles (obliquus externus abdominis muscle, obliquus internus abdominis muscle and transversus abdominis muscle).

The rectus sheath essentially consists of two parts:

• The outer leaflet (lamina externa), is formed from the aponeuroses of the two oblique abdominal muscles.
• The inner leaf (lamina interna) corresponds to the aponeurosis of the transversus abdominis muscle.

The structure of the rectus sheath varies along the course of the rectus abdominis muscle as follows:

• Preumbilically, the rectus sheath is formed only by the two-leaf aponeurosis of the obliquus internus abdominis muscle.
• The rectus abdominis muscle lies between the aponeuroses of the internal abdominal muscle and the transverse abdominal muscle.
• Postumbilically, the rectus abdominis muscle is enveloped by the transversus abdominis muscle and the peritoneum, which is fused with the transversalis fascia.

• Salomon, Geyer, Gille. Anatomy for veterinary medicine. 3rd, updated and expanded edition. Enke Publishing House, 2015