Pelvic girdle fascia

The gluteal fascia (fascia glutea) is dense, covers the gluteus maximus muscle from the outside, and is attached to the dorsal surface of the sacrum and the outer lip of the iliac crest. The deep layer of this fascia separates the gluteus maximus muscle from the gluteus medius muscle and from the muscle that tenses the broad fascia of the thigh. The gluteal fascia passes into the broad fascia of the thigh below.

Two strong ligaments stretched between the sacrum and the tuberosity of the ischium (sacrotuberous) and between the sacrum and the sciatic spine (sacrospinous) together with the greater sciatic notch of the pelvic bone limit the greater sciatic foramen. The piriformis muscle passing through this foramen divides this foramen into two parts - upper and lower, through which vessels and nerves pass. The superior vascular-nerve bundle (the superior gluteal artery and nerve with adjacent veins) exits the pelvic cavity through the superior piriform foramen (foramen suprapiriforme). The thick, powerful inferior vascular-nerve bundle (the inferior gluteal artery and nerve with adjacent veins, the internal genital vessels and the nerve of the same name, as well as the sciatic nerve and the posterior cutaneous nerve of the thigh) passes through the inferior infrapiriform foramen (foramen infrapiriforme).

Since some of the muscles of the lower limb (the psoas major and iliac muscles) originate on the spine and pelvic bones, the fascia covering them is connected to the fascia lining the walls of the abdominal cavity and pelvis (intra-abdominal fascia).

The lumbar fascia (fascia psoatis), being part of the intra-abdominal fascia, covers the large and small psoas muscles in front. Its medial edge is attached to the anterolateral surface of the lumbar vertebrae, their transverse processes and the upper part of the sacrum below. Laterally, this fascia is connected to the fascia covering the quadratus lumborum muscle. The upper edge of the lumbar fascia and the fascia of the quadratus lumborum muscle are fused above with the medial arcuate ligament (of the diaphragm), which is thrown over the psoas muscle from the transverse process of the second lumbar vertebra to the body of the first lumbar vertebra (up to the 12th rib).

Since the large psoas and iliacus muscles merge into a single iliopsoas muscle before entering the thigh, their lumbar and iliac fasciae, fused into one dense fascial sheet, are commonly called the iliopsoas fascia. Attaching to the spine and pelvic bone, this fascia forms a common bone-fascial bed for the iliopsoas muscle. The iliopsoas muscle enters the thigh under the inguinal ligament, where it is attached to the lesser trochanter of the femur. The iliopsoas fascia covering this muscle firmly fuses with the lateral part of the inguinal ligament. In the medial part, this fascia departs from the inguinal ligament and, together with its muscle, continues onto the thigh, where it fuses with the fascia of the pectineus muscle. The bundles of fibrous fibers of the iliopsoas fascia, extending from the inguinal ligament in the medial direction and attached to the crest of the pubic bone (at the medial edge of the iliopsoas muscle), are called the iliopectineal arch (arcus ileopectinem). This arch divides the space under the inguinal ligament into two lacunae: muscular and vascular. The iliopsoas muscle and femoral nerve pass through the laterally located muscular lacuna (lacuna musculorum). The femoral artery (laterally) and femoral vein (medially) pass through the medial vascular lacuna (lacuna vasorum).

Thus, since the iliopsoas fascia together with the muscle of the same name extends from the lumbar region to the upper parts of the thigh, the subfascial space and the bone-fascial bed of the iliopsoas muscle can serve as pathways for the spread of pathological processes from the lumbar and pelvic regions to the thigh. In the medial part of the vascular lacuna between the inguinal ligament and the crest of the pubic bone there is a deep femoral ring (anulus femoralis profundus) of the femoral canal, through which some internal organs (intestinal loop, omentum) can exit from the pelvic cavity to the thigh, forming a femoral hernia.

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