BodyWall

4

Plate248



RectusSheath:CrossSection

Section above arcuate line

Aponeurosis of

external oblique muscle

Aponeurosis of

internal oblique muscle

Aponeurosis of transversus

abdominis muscle

Anterior layer of rectus sheath

Rectus abdominis muscle

Linea alba

Skin

External

oblique muscle

Internal

oblique muscle

Transversus

abdominis muscle

Peritoneum

Extraperitoneal fascia

Transversalis fascia

Posterior layer

of rectus sheath

Falciform

ligament

Subcutaneous

tissue (fatty layer)

Section below arcuate line

Aponeurosis of

external oblique muscle

Aponeurosis of

internal oblique muscle

Aponeurosis of transversus

abdominis muscle

Anterior layer of rectus sheath

Rectus abdominis muscle

Skin

External

oblique muscle

Internal

oblique muscle

Transversus

abdominis muscle

Peritoneum

Extraperitoneal fascia

Transversalis fascia

Median umbilical

ligament (obliterated

urachus) in median

umbilical fold

Medial umbilical

ligament and fold

Subcutaneous

tissue (fatty and

membranous layers)

Aponeurosis of internal oblique muscle splits to form anterior and posterior layers of rectus sheath.

Aponeurosis of external oblique muscle joins anterior layer of sheath; aponeurosis of transversus abdominis

muscle joins posterior layer. Anterior and posterior layers of rectus sheath unite medially to form linea alba.

Aponeurosis of internal oblique muscle does not split at this level but passes completely anterior to

rectus abdominis muscle and is fused there with both aponeurosis of external oblique muscle and that of

transversus abdominis muscle. Thus, posterior wall of rectus sheath is absent below arcuate line, leaving

only transversalis fascia.