Prelab Images - Gluteal Region, Posterior Thigh & Hip
Prelab should consist of reading the lab manual and dissector answers and viewing the dissection video. To begin your study, you may find it useful to look over the Netter's or LWW Atlas images listed below.Step 1. Review the bony landmarks. (Play movie)
Plate N486 or TG3-04 and TG3-05 labels the obturator foramen and groove, the greater sciatic notch, spine of the ischium, lesser sciatic notch, and the ischial tuberosity. Plates N353 or TG6-04A and TG6-04B and N354 show the sacrum and the ilium articulating. Plates N353 or TG6-06 and N503 or TG3-07 show the sacrotuberous and sacrospinous ligaments forming the greater and lesser sciatic foramina. The femur in plate N489 or TG3-07 has the greater and lesser trochanters, gluteal tuberosity, intertrochanteric crest, and trochanteric fossa labeled. Plate N512 or TG3-09 shows the head and neck of the fibula.Step 2. Define the gluteus maximus and reflect it laterally. (Play movie)
Plate N495 or TG3-26 shows the gluteus maximus after the gluteus medius and gluteus maximus fascia has been removed. You want to cut the gluteus maximus muscle from its origin and reflect it laterally (like in the right picture of plate N495 or TG3-26). Careful not to cut through the gluteus medius muscle as you move superiorly and careful not to damage the posterior femoral cutaneous nerve, sciatic nerve, and the sacrotuberal ligament as you move inferiorly (the nerves are better seen in plates N502 or TG3-28 and N503). Remove the fascia from the tensor fasciae latae muscle (N494 or TG3-17). Plate N490 or TG3-12 shows the iliotibial tract insertion on the tibia and plate N491 or TG3-13 shows the insertion of gluteus maximus into the gluteal tuberosity.Step 3. Reflect the gluteus medius and examine the superior gluteal vessels and nerve. (Play movie)
After cleaning the gluteus medius muscle you can peek under the inferior, medial corner of the muscle and find the superior gluteal artery and nerve (plate N502 or TG3-28 and unlabeled in the left picture of plate N495 or TG3-26 and TG3-27). The superior gluteal nerve comes from the sacral plexus (plates N497 or TG3-25A and N499 or TG3-25B) to innervate gluteus medius and minimus as well as tensor fasciae latae (N502 or TG3-28). The superior gluteal artery is a branch off the posterior division of the internal iliac artery (N402 or TG6-17) and it will travel with the superior gluteal nerve (N502 or TG3-28). This neurovascular bundle can be used to separate gluteus medius from gluteus minimus and reflect it laterally to give a view similar to plate N502 or TG3-28. The inferior gluteal artery and nerve can now be identified coming from just below the piriformis muscle (N502 or TG3-28) and going to supply gluteus maximus. The inferior gluteal nerve comes from the sacral plexus (N497 or TG3-25A and N499 or TG3-25B) and the inferior gluteal artery is a branch off the anterior division of the internal iliac artery (plate N402 or TG6-17).Step 4. Define the greater and lesser sciatic foramina and the structures traversing each. (Play movie)
The greater and lesser sciatic foramina are pictured in plate N353 or TG3-07. Plate N503 or TG3-26 shows the piriformis muscle as it emerges from the greater sciatic foramen and plate N502 or TG3-28 shows its relation to the superior and inferior gluteal arteries and nerves and the sciatic nerve. The obturator internus tendon can be spotted passing through the lesser sciatic foramen in plate N503 or TG3-28 (and N502 or TG3-26 also). The superior and inferior gemelli muscles and the quadratus femoris muscle are shown in plates N502 or TG3-26 and N503 or TG3-28. These plates (N502 or TG3-27 and N503 or TG3-28) also show the course of the sciatic nerve in the thigh, the posterior cutaneous nerve of the thigh, and the inferior gluteal nerve. Plate N502 or TG3-28 shows a cutaneous nerve and artery perforating the sacrotuberous ligament that you may find as you clean it. Cut this ligament from the ischial tuberosity and reflect it superiorly. This should reveal the following from plate N503 or TG3-26: the pudendal nerve and internal pudendal artery (artery is not pictured, but runs with the nerve), the sacrospinal ligament, and the nerve to obturator internus and superior gemellus. Plate N353 or TG3-07 shows how the sacrotuberal and sacrospinal ligaments form the greater and lesser sciatic foramina, respectively. The pudendal nerve and the nerve to obturator internus come from the sacral plexus (N499 or TG3-25). Plate N402 or TG6-17 shows the internal pudendal artery branching off the anterior division of the internal iliac artery and plate N411 or TG6-30 shows its course in the perineum after it passes through the lesser sciatic foramen. Plate N398 may give you a better idea of the size of the obturator internus muscle (can also be seen in plates 495 and N503 or TG3-28). Plates N497 and N499 or TG3-25A or TG3-25B review the sacral plexus and label the lumbosacral (L4 and L5) trunk. The sacroiliac and the long and short posterior ligaments as well as the anterior ligaments are seen in plate N353 or TG6-06.Step 5. Dissect the hamstrings from origin to insertion (Play movie)
The hamstring muscles (biceps femoris, semitendinosus, and semimembranosus) are shown in plate N495 or TG3-29. The short head of the biceps femoris is underneath the long head (plate N502 or TG3-29). Plate N502 or TG3-29 shows the sciatic nerve coursing between the two heads. Plate N492 or TG3-57 shows the semitendinosus muscle inserting with the pes anserinus. Plates N502 or TG3-29 and N540 or TG3-66 show the tibial nerve (portion of the sciatic nerve) sending muscular branches to the hamstring muscles, except for the short head of biceps femoris, which receives a branch from the common fibular nerve (plate N540 or TG3-65).Step 6. Define the popliteal fossa, clean and identify its contents. (Play movie)
Plate N495 or TG3-29 and TG3-31 show the popliteal fossa and plate N502 or TG3-31 reveals the tibial nerve with its medial sural branch and the common fibular nerve with its lateral sural branch (which runs near the biceps femoris tendon). The lesser saphenous vein is shown terminating into the popliteal vein in plate N502 or TG3-70. Plates N493 and N502 or TG3-31 show the popliteal artery and vein passing through the adductor hiatus and in the popliteal fossa. You may also find popliteal lymph nodes, which are shown in plate N546 or TG3-70.
Plate N517 or TG3-31 shows the popliteal artery and its superior medial, superior lateral, inferior medial, and inferior lateral genicular branches. This view does not show the middle genicular artery because it runs deep into the knee and does not run laterally like the other 4 branches. Plate N512 or TG3-62 labels all 5 branches, but it is still difficult to appreciate the middle genicular artery diving deep into the knee.
Updated: 07 Nov 2011
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