The anatomical basis for femoral nerve palsy following iliacus hematoma.

With increased use of anticoagulant agents, femoral neuropathy subsequent to hemorrhage within the iliacus muscle has become a frequent clinical problem. The mechanism for this type of femoral nerve palsy was studied in dissections of the iliac region and by injections of latex into fascial planes in that area. In most dissections, up to four fascial layers, parallel to the iliacus sheath, could be identified. Variable states of fusion of these layers often produced up to three pouches, separated by loose connective tissue or fat. These fasciae (called "lamina peritonealis," "lamina transversalis," "lamina preiliaca," and "lamina iliaca") appear to be variable adult remnants of distinct fascial layers present in the posterior abdominal wall during embryological development, and serve to strengthen the intrinsic fascia of the iliacus muscle. Latex injected into the iliacus sheath spread from the midlumbar region to the femoral triangle, surrounding, compressing, and stretching the femoral nerve in different parts of its course. These observations suggest an anatomical basis for femoral nerve palsy during iliacus hematoma.