Rectus Sheath

vagina musculi recti abdominis

The rectus sheath is the aponeurotic envelope encasing the rectus abdominis muscle, formed by the splitting and reunion of the lateral abdominal muscle aponeuroses. Above the arcuate line it has anterior and posterior walls; below the arcuate line all aponeurotic layers pass anteriorly, leaving the posterior wall deficient.

Anatomical Data

Boundaries & Contents

Location	Front of the abdomen on each side of the midline
Boundaries	Anterior wall: external oblique aponeurosis and the anterior lamina of internal oblique above the arcuate line; all three aponeuroses below it Posterior wall: posterior lamina of internal oblique and the transversus abdominis aponeurosis above the arcuate line; only transversalis fascia below it Medially: linea alba Laterally: linea semilunaris
Contents	Rectus abdominis Pyramidalis (when present) Superior and inferior epigastric vessels Terminal parts of the lower six thoracic (T7 to T12) nerves

Biomechanics

Function & Actions

Holds the rectus abdominis in place and links it to the lateral abdominal muscles.

Clinical Relevance

Clinical Notes

Rectus sheath haematoma is a common emergency presenting as acute abdominal pain, often in anticoagulated patients following coughing or sneezing. Below the arcuate line haematomas can dissect freely into the pelvis. CT is diagnostic. Conservative management suffices for most cases; surgical or angiographic haemostasis is required for expanding haematomas.

Pathology

Common Injuries & Conditions

Rectus Sheath Haematoma

Bleeding within the rectus sheath from epigastric vessel rupture or rectus muscle tear, producing acute anterior abdominal pain with a palpable tender mass that does not cross the midline, diagnosed by CT.

Explore

More in Abdomen

Browse all of Abdomen →