1. Gluteal region
Extends from the iliac crest above to the gluteal fold below.
The superficial fascia is thick dense and fatty, the deep fascia is thick over the anterior border of gluteus maximus while elsewhere is thin. It continuous below with the fascia lata and attached to the iliac crest above.

2. Cutaneous nerves of the gluteal region
1- lateral cutaneous branches from subcostal (T12) and iliohypogastric nerve(L1) supply the upper lateral quadrant of the buttock.
2-The lower lateral quadrant is supplied by the lateral cutaneous nerve of the thigh(L2,L3).

3. 3- The lower medial quadrant supplied by the posterior cutaneous nerve of the thigh which curve over the lower border of gluteus maximus (inferior cluneal nerve).
4- The upper medial quadrant supplied by the lateral cutaneous branches from dorsal rami L1-L3 (superior cluneal nerves) and the lateral cutaneous branches of the dorsal rami of S1-S3 (middle cluneal nerves)
The perforating cutaneous nerve (S2,3) of the sacral plexus, pierces the sacrotuberous ligament and gluteus maximus mid way between coccyx and ischial tuberosity.

4. Cutaneous nerves of the gluteal region

5. Sacrotuberous ligament:
It is a strong band passes upwards from the medial side of the ischial tuberosity to the margins of the sacrum and coccyx and to both posterior iliac spines. The lateral edge of the ligament forms the posteromedial border of the greater and lesser sciatic notches.

6. Sacrotuberous ligament

7. Sacrospinous ligament:
This is a thick triangular band it passes from the the ischial spine to the margin of coccyx and last piece of the sacrum deep to the sacrotuberous ligament.

8. Sacrospinous ligament

9. Sciatic foramina
The greater sciatic foramen: bounded by the greater sciatic notch of the hip bone the sacrotuberous ligament and the sacrospinous ligament, it transmit structures from the pelvis to the gluteal region.

10. The lesser sciatic foramen: bounded by the lesser sciatic notch and the sacrospinous and sacrotuberous ligaments, it transmits structures between the gluteal region and the perineum.

11. Structures which enter the gluteal region from the pelvis
1- Remain in the gluteal region these include; the gluteal vessels and nerves and the piriformis muscle.
2- Descend from the gluteal region into the back of the thigh include; the sciatic nerve, the posterior cutanous of the thigh and branches of the inferior gluteal vessels.

13. 3- Turn forwards through the lesser sciatic foramen into the perineum include; the internal pudendal vessels, pudendal nerve and nerve to obturator internus muscle.

14. Muscles of the gluteal region
The large muscles include: Gluteus maximus, medius and minimus.
The small muscles include: piriformis, obturator internus, superior and inferior gemelli and quadratus femoris.

15. Large muscles of the gluteal region

16. Small muscles of gluteal region

17. Piriformis muscle
it is a land mark muscle in the gluteal region. It is conical muscle arise in the pelvis from the pelvic surface of the middle three pieces of the sacrum, It passes through the greater sciatic foramen to be inserted in the upper border of the greater trochanter of the femur.
Nerve supply from the first and second sacral nerves.

19. Gluteal vessels Include Inferior gluteal artery
Superior gluteal artery

20. Inferior gluteal artery:
it is a branch of the internal iliac artery emerges from the pelvis below piriformis muscle accompany the inferior gluteal nerve supply the gluteus maximus and gives cutaneous branches to the buttock and the back of the thigh, it also give a slender companion artery to the sciatic nerve.

21. Superior gluteal artery
arise from the internal iliac artery accompany the superior gluteal nerve, it enters the gluteal region above the piriformis muscle. It divided into
Superficial branch passes between the gluteus maximus and piriformis muscles.
Deep branch follow the superior gluteal nerve supply the gluteus medius, minimus and the hip joint.

22. Gluteal vessels and nerves

23. Nerves of the gluteal region
Inferior gluteal nerve (L5 S1 S2): it is a branch from the sacral plexus enter the gluteal region with the posterior cutanous nerve of the thigh inferior to the piriformis m. supply gluteus maximus m.

24. Superior gluteal nerve (L4 L5 S1): it is a branch from the sacral plexus enters the gluteal region above the piriformis m. divided into numbers of branches supply the glueus medius , minimus and tensor fasciae lata m.

25. Sciatic nerve (L4 L5 S1 S2 S3)
it is the thickest nerve in the body arise from the sacral plexus, pass inferior to the piriformis m through the greater sciatic foramen, deep to the gluteus maximus m. in the upper part of its course it descends over:
1- ischial wall of the acetabulum.
2- Obturator internus m. and the 2 gemelli ms.
3- Quadratus femoris m.

26. It leaves the buttock by passing deep to the long head of the biceps femoris, it supply the hamstring ms and gives articular branch to the hip joint. the sciatic nerve then descends on the posterior surface of the adductor magnus m. at the lower third of the thigh it divided into medial branch (tibial nerve) and lateral branch (common peroneal nerve).

27. Sciatic nerve

28. b- Both gluteal arteries. c- Lateral circumflex artery.
Anastomosis between branches from the internal and external iliac arteries
1- between medial circumflex femoral artery and
a- obturator artery.
b- Both gluteal arteries.
c- Lateral circumflex artery.
d- perforating branches of the profunda artery.

29. 2- Between The superior gluteal artery and
a- lateral circumflex artery.
b- Superficial circumflex iliac artery.
3- between internal pudendal artery, deep and superficial external pudendal arteries of the femoral artery.

30. The back of the thigh (the posterior compartment)
The muscles of the back of the thigh are the hamstring muscles which are extensors of the hip joint and flexors of the knee joint, all arise from the ischial tuberosity except the short head of the biceps m. and all are inserted in the bones of the leg.
These muscles include: biceps femoris, semitendinosus and semimembranosus. All supplied by the sciatic nerve.

31. posterior cutanous nerve of the thigh
which is a branch of the sacral plexus enters the thigh inferior to the piriformis muscle through the greater sciatic foramen. it descend through the posterior midline of the thigh giving small branches from both sides to the skin of the back of the thigh and the popliteal fossa, it pierce the fascia lata and ends as a cutaneous branches over the calf.

32. Posterior cutaneous nerve of the thigh

33. The blood supply of the posterior compartment are the perforating branches from the profunda femoris artery.

34. The popliteal fossa
It lies behind the knee, the lower 1/3 of the femur and the upper part of the tibia. It is diamond in shape.
The superficial fascia of the fossa contain little fat, while the deep fascia is thin, strong and firmly attached to the tendons.

35. Bounderies:
Upper lateral biceps femoris m.
Upper medial semimembranosus and semitendinosus ms.
Lower lateral and medial the 2 heads of the gastrocnemius m.
The anterior wall is the popliteal surface of the femur, the posterior capsule of the knee joint and the fascia of the popliteus m.
The posterior wall is the deep fascia of the fossa.

37. Contents of the fossa These include: 1- The popliteal vessels.
2- Branches of the sciatic nerve, the tibial and common peroneal nerves.
3- Popliteal lymph nodes.
4- Posterior cutaneous nerve of the thigh.

38. Contents of the fossa

39. The popliteal vessels
These are the direct continuation of the femoral vessels enter the fossa through the adductor hiatus. They lie anterior to the tibial nerve, the common peroneal nerve pass laterally accompany the tendons of the biceps muscle. The popliteal artery ends at the lower border of the popliteus muscle by dividing into anterior and posterior tibial arteries.

40. The popliteal artery
begin at the adductor hiatus and ends at the lower border of the popliteus m. where it divided into anterior and posterior tibial arteries. The popliteal artery is anterior to the semimembranosus m. Popliteal vein, tibial nerve, the heads of the gastrocnemius and plantaris ms.

41. The popliteal artery

42. Branches:
1- muscular branches to the hamstring ms. And to the muscles of the calf.
2- Articular branches these are the lateral and medial superior and inferior genicular and middle genicular arteries to the knee joint correspond to the genicular branches from the tibial and common peroneal nerves. they anastomosed with the branches from the lateral circumflex femoral, descending genicular arteries, and the recurrent branches of the anterior tibial artery

44. The popliteal vein
formed by the union of the anterior tibial, the posterior tibial and the peroneal veins at the lower border of the popliteus muscle, it lies superficial to the artery and between it and the tibial nerve. it receive tributaries correspond to the branches of the popliteal artery and the lesser saphenous vein. it become the femoral vein at the adductor hiatus.

46. Tibial nerve (L4 L5 S1 S2 S3)
It is the largest of the two terminal branches of the sciatic nerve, it begins above the popliteal fossa descends vertically in the fossa, Lying first on the lateral side of the popliteal artery then posterior to it and finally medial to it then it pass between the two heads of the gastrocnemius muscle and under the soleus muscle. It supply the muscles of the back of the thigh and leg, the sole of the foot, the skin of the lateral and lower half of the back of the leg and sole of the foot.

47. Tibial nerve

48. Branches in the popliteal fossa
1- sural nerve: it is a cutaneous branch descend in the groove between the two heads of the gastrocnemius m. it pierce the deep fascia about the middle of the back of the leg join the peroneal communicating branch from the peroneal nerve, supply the skin of the lower posterior part of the leg and the skin of the lateral side of the dorsum of the foot. It accompany the small saphenous vein.

49. 2- Muscular branches to the gastrocnemius, plantaris, soleus and popliteus ms.
3- Articular branches, it gives superomedial, inferomedial and middle genicular branches to the knee joint, accompanied the corresponding branches from the popliteal artery

51. Common peroneal nerve (L4 L5 S1 S2)
It is smaller than tibial nerve runs follow the tendon of biceps femoris m. along the upper lateral border of the popliteal fossa to the back of the head of the fibula, then curves forwards along the neck of the fibula deep to the peroneus longus m. here it divides into deep and superficial branches.

53. Branches in the popliteal fossa:
1- cutaneous branches, these include the peroneal communicating branch which arise in the upper part of the popliteal fossa descend on the posterolateral side of the calf to join the sural nerve about the middle of the back of the leg, it supply the proximal 2/3 of the posterolateral part of the leg.

54. Lateral cutaneous nerve of the calf arise on the lateral head of the gastrocnemius m. supply the lateral side of the leg.

55. Recurrent genicular branch arise where the common peroneal nerve divides into superficial and deep branches, it ascends to the knee joint.
3- muscular branch to the short head of the biceps femoris m. arise high up in the fossa.