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The vagina of the rectus abdominis
Last reviewed: 06.07.2025
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The vagina of the rectus abdominis muscle (vagina m.recti abdominis), its anterior and posterior walls, is formed by the aponeuroses of the three broad abdominal muscles.
The structure of the anterior and posterior walls of the rectus abdominis sheath is not the same. Along the upper part of the rectus muscle, above the transverse line drawn between the superior anterior iliac spine of the right and left sides, the aponeurosis of the internal oblique muscle of the abdomen splits into two plates - anterior and posterior.
The anterior plate of the aponeurosis together with the aponeurosis of the external oblique muscle of the abdomen forms the anterior wall of the sheath of the rectus abdominis muscle. The posterior plate, merging with the aponeurosis of the transverse muscle of the abdomen, forms the posterior wall of the sheath of the rectus abdominis muscle.
Below this level of the indicated transverse line (4-5 cm below the navel), the aponeuroses of all three abdominal muscles pass to the anterior surface of the rectus abdominis muscle and form the anterior wall of its sheath. Therefore, below the indicated transverse line, the rectus abdominis muscle is covered from behind only by the transverse fascia. The lower edge of the tendinous posterior wall of the sheath of the rectus abdominis muscle is clearly visible from the abdominal cavity (through the peritoneum) or after removal of the rectus abdominis muscle and is called the arcuate line (linea aruata).
Below the arcuate line, on the posterior surface of the rectus abdominis muscle, there is only transverse fascia, behind which are the retroperitoneal tissue and peritoneum.