Together with the iliac fascia, it continues down to the inguinal ligament where it forms the iliopectineal arch which separates the muscular and vascular lacunae.

It pierces the vascular lacuna near the saphenous hiatus and supplies the skin below the inguinal ligament (i.e. proximal, lateral aspect of femoral triangle).

The iliopectinal arch thus forms a septum which subdivides the space deep to the inguinal ligament into a lateral muscular lacuna and a medial vascular lacuna.

The vascular lacuna (Latin: lacuna vasorum) is the medial compartment beneath the inguinal ligament, for the passage to the femoral vessels, lymph node, and femoral branch of the genitofemoral nerve.

These immediately split into the internal and external iliac arteries, the latter of which descends along the medial border of the psoas major to exits the pelvis area through the vascular lacuna under the inguinal ligament.

The Muscular lacuna (Latin: lacuna musculorum) is the lateral compartment inferior to the inguinal ligament, for the passage of the iliopsoas muscle and femoral nerve; it is separated by the iliopectineal arch from the vascular lacuna.