Abdominal Structures related to the Lower Limb
The Psoas Major, psoas minor, and iliacus muscles of the lower limb have their origin
within the abdomen. The lumbar plexus, which provides for a lot of the nerves to the
lower limb, is also formed in the abdomen.
The Fasciae
The transversalis fascia forms an internal parietal lining of the entire abdominopelvic
cavity. In the lumbar region it covers the quadratus lumborum and the psoas muscles and
is called the quadratus lumborum fascia and the psoas fascia. In the abdomen this
transversalis fascia is attached to the anterior longitudinal ligament that lays on the
anterior surface of the vertebrae, it then sweeps over the psoas muscle (as the psoas
fascia) and at this muscle’s lateral edge, attaches to the tips of the transverse processes of
the vertebrae. Then it goes over the quadratus lumborum muscle (as the quadratus
lumborum fascia) and at this muscle’s lateral edge attaches to the thoracolumbar fascia
(which has come forward after covering the deep muscles of the back). It then continues
forward on the underside of the transversus abdominus muscle. It attaches to the inner lip
of the iliac crest and covers the iliacus muscle.
The iliacus fascia is different and is an aponeurotic layer that covers the iliacus muscle
and may be separated from the transversalis fascia by fat and areolar tissue and continues
with it deep to the inguinal ligament with the iliopsoas muscle. The iliacus fascia is
attached to the inguinal ligament laterally. Medially, it follows the medial border of the
iliopsoas muscle, attaches to the iliopubic eminence and extends over the superior pubic
ramus and over the pectineus muscle and eventually blends with deeper layers of the
fascia lata behind the saphenous opening.
The femoral sheath is a diverticulum of the transversalis fascia and is not contributed to
by the pectineus or iliacus fasciae.