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Illustration - Muscles of the thoracic and abdominal wall

Rectus sheath

Rectus sheath

Pronunciation

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Other Terms:
Vagina musculi recti abdominis, Gaine du muscle droit de l'abdomen


Description
The rectus abdominus muscle is enclosed in a sheath formed by the aponeuroses of the oblique muscles and transverses abdominus muscle. At the lateral margin of the rectus abdominus, the aponeurosis of the internal oblique divides into two lamellae, one of which passes in front of the rectus, blending with the aponeurosis of the external oblique muscle, the other, behind it, blending with the aponeurosis of the transverses abdominus muscle. After enveloping the rectus the internal and external layers join again at the medial border of the rectus where they form the linea alba. This arrangement of the aponeurosis exists from the costal margin to midway between the umbilicus and symphysis pubis, where the posterior wall of the sheath ends in a thin curved margin, the arcuate line. Below this level the aponeuroses of all three muscles pass in front of the rectus abdominus muscle. Since the tendons of the internal oblique and transverses abdominus only reach as high as the costal margin, it follows that above this level the rectus sheath is deficient behind, the muscle resting directly on the cartilages of the ribs, and being covered merely by the tendon of the external oblique.
Latin
Vagina musculi recti abdominis
French
Gaine du muscle droit de l'abdomen

Structural Label Key