Trunk (thorax, abdomen, back)
Posterior Leaf of the Rectus Sheath
Vagina musculi recti abdominis, lamina posterior
- Origin
- Formed by the aponeurosis of the transversus abdominis muscle and the posterior layer of the split aponeurosis of the internal oblique abdominis muscle
- Insertion
- Fuses at the midline with the posterior leaf of the opposite side at the linea alba; absent caudal to the arcuate line, where all three aponeuroses shift to the anterior leaf
- Function
- Envelops the posterior surface of the rectus abdominis muscle in the upper part of the abdominal wall
- Innervation
- No independent motor innervation; sensory via the anterior cutaneous branches of the thoracoabdominal nerves
- Movement & chain
- Provides a firm dorsal support behind the upper rectus abdominis; distributes intra-abdominal pressure under exertion.
- Palpation
- Located deep to rectus abdominis above the arcuate line (line of Douglas); cannot be palpated externally.
- Clinical
- Deficient inferior to the arcuate line where only transversalis fascia supports the rectus; site of Spigelian hernias and rectus sheath hematomas.
- Segmental innervation
- T7–T12 (intercostal nerves)
- In clinical practice
- Wound management post-laparotomy/chest drain and abdominal wall monitoring; support incision site during coughing to prevent wound dehiscence.
- Region in the model
- Trunk (thorax, abdomen, back)