Rectus Sheath Anatomy PDF

L15: RECTUS SHEATH RECTUS SHEATH Rectus abdominis and pyramidalis muscles are enclosed in aponeurotic tendinous sheath formed by layering of the aponeuroses of 3 flat muscles Sheath completely encloses upper ¾ rectus abdominis Sheath covers anterior surface of lower ¼ rectus abdominis Transition poi...

L15: RECTUS SHEATH RECTUS SHEATH Rectus abdominis and pyramidalis muscles are enclosed in aponeurotic tendinous sheath formed by layering of the aponeuroses of 3 flat muscles Sheath completely encloses upper ¾ rectus abdominis Sheath covers anterior surface of lower ¼ rectus abdominis Transition point = arcuate line Arcuate line is : The lower free edge of the posterior wall of the rectus sheath. Is located midway between toe umbilicus and pubic symphysis Rectus Sheath is Formed by splitting up of the aponeurosis of the internal oblique at the lateral border of the rectus muscle. Splitting extends from the costal margin to the midway umbilicus and pubis symphysis. Below this the internal oblique does not split, But passes with the transversus aponeurosis in front of the muscle. 1. Above costal margin: Anterior wall: Only EO aponeurosis Posterior wall: Deficient so rectus muscle rests on 5th 6th and 7th Costal cartilage 2. Between the costal margin & arcuate line: Anterior wall: EOA + anterior lamina of IOA. Posterior wall: 1OA and TAA 3. Below arcuate line: Anterior wall: Aponeurosis of all three muscles Posterior wall: Transversalis fascia and peritoneum. 4. Contents of Rectus sheath 1. Rectus abdominis muscle and pyramidalis 2. Superior and inferior epigastric vessels 3. 7th - 11th Intercostal and subcostal nerves 4. Lymphatic vessels