Lab Manual - Hip & Posterior Thigh & Leg

Assignments:

Learning Objectives:

Upon completion of this session, the student will be able to:

  1. Describe the anatomy of the lateral femoral (hip) region, including the gluteal muscles, their nerve supply, and their actions in locomotion.
  2. Identify the sacral plexus, its general plan, and its major branches in the hip and posterior thigh regions.
  3. Describe the muscular anatomy of the posterior thigh, its muscles, their nerve supply, and their actions in locomotion.
  4. Predict the functional loss and cutaneous areas affected by a given nerve injury to the hip and posterior thigh region; or conversely, given a functional and/or cutaneous loss, be able to predict which nerve or nerves are involved and the probable level of the injury.
  5. Define the popliteal fossa and give the spatial relationships of its contents.
  6. Recall the general plan of the collateral circulation at the hip and knee.
  7. Describe the arrangement, specializations and compartments of the fascia of the leg.
  8. Identify the muscles of the posterior compartment of the leg and give their functional significance in locomotion.
  9. Identify the vascular supply of the posterior compartment of the leg.
  10. Identify the nerves of the posterior compartment of the leg, the muscles and cutaneous regions supplied by them, so that given a functional and/or cutaneous loss one can predict the nerve and the probable level of injury.

Procedure:

1. Review the bony landmarks. (Play movie; View images: N 353, 354, 486, 489, 502, 512, TG 6-04A, 6-04B, 3-05, 6-06, 3-07, 3-09)

Identify on the skeleton: obturator foramen and groove, the greater sciatic notch (foramen), spine of the ischium, the lesser sciatic notch (foramen), ischial tuberosity. Locate the sacroiliac articulation. The sacrotuberal and sacrospinal ligaments help to form the greater and lesser sciatic foramina. On the femur, locate the lesser and greater trochanters, gluteal tuberosity, intertrochanteric crest, trochanteric fossa of femur.

Examine the tibia and identify the condyles, tuberosity, soleal line, anterior border and medial malleolus. On the fibula, identify the head and neck of the fibula and the lateral malleolus. In the foot identify the tarsals (calcaneus, talus, navicular, cuboid, 1st, 2nd, and 3rd cuneiform bones), metatarsals and phalanges.

Bony structures of the hip

2. Turn the body over, and skin the posterior surface of the lower limb, preserving the cutaneous vessels and nerves. (Play movie; View images: N 547, TG 3-03)

Turn the body over (prone position). Skin the posterior surface of the lower limb. Watch for cutaneous nerves and veins.

3. Clean the subcutaneous tissue from the posterior surface of the lower limb, trace the lesser saphenous vein, and identify the cutaneous nerves. (Play movie; View images: N 496, 499, 501, 502, 541, 542, 545, 547, TG 3-03, 3-25A, 3-25B, 3-26, 3-28, 3-29, 3-31, 3-39, 3-65)

Beginning on the lateral side of the foot, trace the lesser saphenous vein behind the lateral malleolus and along the posterior side of the leg. Look for small branches of the lesser saphenous vein perforating the crural fascia to join the deep veins. What nerves accompany the lesser saphenous vein? Where does the vein disappear and where does it terminate?

In the calf, locate the lateral sural cutaneous nerve, medial sural cutaneous nerve (with lesser saphenous vein), and sural nerve (how formed? where does it distribute and by what name? ).

The posterior femoral cutaneous nerve runs down the midline of the back of the thigh deep to the fascia lata. Cut vertically through the fascia lata on either side of the midline on the posterior side of the thigh, locate the nerve (which usually clings to the underside of the fascia), and then trace it toward the buttock. Identify its inferior cluneal and perineal branches.

4. Define the gluteus maximus and reflect it laterally. (Play movie; View images: N 490, 491, 493, 494, 502, 503, TG 3-12, 3-13, 3-17, 3-26A, 3-26B, 3-28)

Clear the gluteal region of all superficial fascia. Define the gluteus maximus fascia and the gluteal aponeurosis covering the gluteus medius muscle. Define the gluteus maximus muscle. Reflect the muscle laterally from its origin on the sacrum and sacrotuberous ligament to expose the deeper structures. Care must be taken in removing it from the sacrotuberous ligament to not remove the ligament. Cut along its superior border to separate the gluteus maximus from the gluteal aponeurosis covering the gluteus medius. In reflecting the muscle do not injure deeper structures along its inferior border, especially the sacrotuberal ligament, the posterior femoral cutaneous and sciatic nerves. Note that most of the muscle is enclosed within the deep fascia. Now locate the tensor fasciae latae muscle. Slit open the fascia lata vertically and expose the muscle. Note that both gluteus maximus and tensor fasciae latae insert via the iliotibial tract of the fascia lata. Where does this attach? Now observe the other insertion of gluteus maximus into the gluteal tuberosity.

5. Reflect the gluteus medius and examine the superior gluteal vessels and nerve. (Play movie; View images: N 502, 512, TG 3-25A, 3-25B, 3-26, 3-27, 3-28, 6-17)

Remove the gluteus medius fascia as far anterior as the anterior superior iliac spine. Trace the muscle to its insertion. Locate the superior gluteal artery and nerve coursing deep to the gluteus medius muscle; what is their source? This plane can be used to separate the gluteus medius from the underlying gluteus minimus. Reflect the gluteus medius from its origin and define the gluteus minimus. Trace the superior gluteal artery and nerve to the muscles supplied, including the tensor fasciae latae. What is the innervation and blood supply to gluteus maximus? Now consider the insertions and actions of the gluteal muscles.

6. Define the greater and lesser sciatic foramina and the structures traversing each. (Play movie; View images: N 353, 398, 402, 411, 495, 497, 499, 502, 503, TG 3-07, 3-25A, 3-25B, 3-26, 3-27, 3-28, 6-06, 6-17, 6-30)

Locate the piriformis muscle and trace it to its insertion. Through what foramen does it exit the pelvis? Note its relation to the superior gluteal neurovascular bundle and to the inferior gluteal artery, vein and nerve and sciatic nerve.

Define the obturator internus tendon and trace to its insertion. Through what foramen does it pass? Define the superior and inferior gemellus muscles. Inferior to the inferior gemellus muscle, locate and define the quadratus femoris muscle. What major action do these muscles have in common?

Trace the sciatic nerve into the thigh, noting relations to the hip muscles. Review the posterior femoral cutaneous nerve. Identify the inferior gluteal nerve to the gluteus maximus.

Clean the sacrotuberal ligament; is there a perforating cutaneous nerve and artery associated with it? Reflect the ligament from the ischial tuberosity and identify the following as they lie on the sacrospinal ligament: pudendal nerve, the internal pudendal artery and vein, and the nerve to obturator internus and superior gemellus. Note that there is usually a web of fascia extending between the two ligaments, which must be removed to see the structures clearly. Define the sacrospinal ligament. Note how it and the sacrotuberal ligament form the greater and lesser sciatic foramina. What structures does each transmit? Review the course of the pudendal nerve and internal pudendal artery. Now observe the complete origin and course of the obturator internus muscle. Confirm its innervation.

Review completely the muscles, the nerves supplying them, and the blood supply to the region. Note how the lumbosacral trunk and sacral nerves unite to form the sacral plexus. Consider the formation of the sacral plexus and trace its major branches.

Read about the sacroiliac articulation, noting specifically the bones entering into its formation and how the ligaments support the joint: long and short posterior sacroiliac, interosseous sacroiliac, and anterior sacroiliac ligaments.

7. Dissect the hamstrings from origin to insertion (Play movie; View images: N 492, 495, 502, 540, TG 3-29, 3-57, 3-65, 3-66)

Uncover and dissect the biceps femoris, semitendinosus and semimembranosus muscles. Note the manner of attachment to the ischial tuberosity. Locate the short head of biceps femoris muscle. Note specifically the relation of biceps femoris to the sciatic nerve. Trace semitendinosus to its insertion and complete the dissection of the pes anserinus. Trace the innervation to all muscles. Do you find a branch from the tibial division of the sciatic nerve to adductor magnus; and one from the common fibular division to the short head of biceps?

Arteriogram of lower limb vessels

8. Define the popliteal fossa, clean and identify its contents. (Play movie; View images: N 493, 495, 502, 512, 517, 546, TG 3-29, 3-31A, 3-31B, 3-62, 3-70)

Define the boundaries of the popliteal fossa. Remove the popliteal fascia (part of what fascia?). Identify the muscles bounding the fossa. Clear the fat and identify the tibial nerve and its medial sural cutaneous branch; also identify the common fibular (peroneal) nerve and its lateral sural cutaneous branch. Note the relationship to the biceps femoris tendon as the nerve courses around the neck of the fibula. Now clear the popliteal vein and trace the lesser saphenous vein to its termination. Explore the popliteal artery, the adductor hiatus and the manner in which the vein and artery enter and leave the popliteal fossa. Where exactly is the popliteal fossa located in the lower extremity? Do you find lymph nodes here?

Surface features of the popliteal fossa
Popliteal artery and vein

Remove the popliteal vein and expose the popliteal artery. Identify the muscular branches to hamstrings and sural branches. Then locate the superior medial and superior lateral genicular arteries crossing the heads of origin of the gastrocnemius muscles, but lying directly on the bone. Locate a middle genicular artery entering the posterior side of the knee joint.

9. Remove the subcutaneous tissue from the posterior surface of the leg and dissect the superficial posterior compartment. (Play movie; View images: N 516, 518, TG 3-30, 3-33, 3-35)

Remove the subcutaneous tissue of the posterior leg and expose the crural fascia. Carefully examine the flexor retinaculum, a thickening of the crural fascia.

In the present and following dissection, open each compartment of the leg by cutting longitudinally through the crural fascia. Explore the compartments; locate and identify septa and attachments.

Open the superficial posterior compartment and dissect the gastrocnemius, plantaris and soleus muscles. Note how the gastrocnemius and soleus (and sometimes plantaris) combine into a single tendon and insert into the calcaneus. What is the triceps surae? Cut through the midpoint of the gastrocnemius and reflect it to expose the soleus and popliteus muscles. Dissect the popliteus muscle by removing its fascia.

10. Reflect the soleus and dissect the deep posterior compartment. (Play movie; View images: N 512, 515, 516, 517, 518, 520, 522, 529, 531, 534, 535, 536, 541, 542, TG 3-32, 3-34, 3-35, 3-36, 3-38, 3-39, 3-51, 3-50, 3-53, 3-62, 3-65, 3-66, 3-67A)

Remove the soleus from its fibular attachment and expose the lower portion of the transverse intermuscular septum. Cut through the septum, enter the deep posterior compartment, and identify the flexor digitorum longus, tibialis posterior and flexor hallucis longus muscles. Trace these tendons to the posterior side of the medial malleolus and deep to the flexor retinaculum. Note the rearrangement of the tibialis posterior and flexor digitorum longus tendons. Do not trace them into the foot at this time.

Trace the blood vessels of the leg. Begin with the popliteal artery, and note that it divides into anterior and posterior tibial arteries at the lower border of the popliteus muscle. Follow the anterior tibial artery to the upper free edge of the interosseous membrane where it passes into the anterior compartment.

Arteriogram of the popliteal artery

Follow the posterior tibial artery, noting muscular, malleolar, and calcaneal branches. The fibular (peroneal) artery is hidden by the flexor hallucis longus muscle. Trace the fibular artery in relation to the interosseous membrane and note its perforating branch. Significance? Do not trace the posterior tibial artery into the foot.

Trace the tibial nerve, noting branches to superficial posterior compartment muscles, its course between the two heads of gastrocnemius and its course deep to the origin of the soleus. Trace the nerve through the deep posterior compartment and observe its relationship to the posterior tibial artery; note its muscular branches and its relations behind the medial malleolus.

Consider actions of muscles of the posterior compartment of the leg. What vessels constitute the collateral blood supply of the knee?