PROCEDURE - ANTERIOR THIGH

1. PRE-WORK (before lab) review the organization of the bony lower extremity from your atlas or on an articulated skeleton in the lab.
    (Netter479) (Netter504)

a) The proximal femur articulates with the pelvis in a ball and socket joint.  The head and neck of the femur project medially at a sharp angle into the socket on the pelvis.

b) On the distal end of the femur, the bone diverges into two articulating surfaces of the knee joint. These are the lateral and medial condyles of the femur which rest on the tibial plateau.

c) The patella is a thick circular to triangular plate of bone that articulates with the patellar surface of the femur.  The patella is a sesamoid bone (i.e. a bone embedded within a tendon).

d) Lateral to the tibia is the smaller fibula, which has a head that articulates with the lateral side of the tibia. 

e) The tibia and fibula terminate at the ankle forming a medial malleolus (tibia) and lateral malleolus (fibula) that form part of the ankle joint.

2. Turn the donor over to the supine position.

CLINICAL EXERCISE - Femoral exposure & control

3. Trauma is commonly associated with an open wound and hemorrhage. Exsanguination (life threatening loss of blood) is the leading cause of death from trauma injury. To improve outcome in trauma hemorrhage control the American College of Surgeons Committee on Trauma in 2010 codified a series of exposure techniques to gain access to proximal regions of major vessels (the Advanced Surgical Skills for Exposure in Trauma, or ASSET course).

In this clinical exercise, you have the chance to perform the ASSET common femoral artery exposure technique on your donor.  For the steps to perform:
                                 ------ click here ------

4. Extend the femoral skin incision distally along the anterior thigh to just past the patella at the knee.
    (Figure525) (Photo5055)

5. Working from superior to inferior, reflect the skin in the plane between superficial and deep fascia over the thigh.
    (Photo5082)

As you reflect the skin and superficial fascia of the thigh, look for the great saphenous vein which will course in the superficial fascia approximately parallel to and on the medial side of your skin incision. Try to preserve a segment (~10-20cm) of the great saphenous vein near the groin for later study.

Other small superficial veins form a superficial network of veins connected to the great saphenous vein and can be discarded while removing skin and superficial fascia to clear the dissection field. (Figure526) (Netter473)

The great saphenous vein is a 'vessel of choice' for many vascular surgical procedures (e.g. coronary bypass surgery), thus it is possible that your donor may be missing one or both veins (particularly likely if the individual had multiple bypass procedures).

The great saphenous vein arises from the medial dorsal venous arch of the foot, extends over the medial condyle of the knee and then courses to the femoral triangle to empty into the femoral vein.

Numerous small to medium sized veins drain from the surrounding superficial fascia into the great saphenous vein. In addition, deeper veins perforate through the fascia lata connecting the superficial and deep venous drainage systems.

6. Extend your femoral exposure incision through the fascia lata inferiorly to the medial side of the patella at the knee.
    (Figure527) (Netter473) (Photo5083)

7. Lift the fascia lata and using scissors make an incision though the fascia lata from the femoral exposure opening laterally and medially parallel to the inguinal ligament.
    (Figure527a) (Netter473) (Photo5083a)

This exposes the femoral triangle, containing the femoral artery, nerve and vein.

8. Spread the fascia lata widely to open the anterior compartment of the thigh cutting fascia lata away from the knee to fully open the anterior compartment.
    (Photo5084)

When trimming fascia lata leave the iliotibial band intact along the lateral side of the thigh.

Limbs are surrounded by tough fascia, in the case of the thigh the fascia lata. Septa extend from this outer fascia separating the limb into a series of compartments. The thigh has anterior, posterior and medial compartments.

9. Dissect into the fascia medial to the femoral artery isolated in the vascular access procedure to identify the common femoral vein.
    (Figure528) (Netter490) (Photo5060)

Part of the fascia you are separating is the femoral sheath. During the vascular control exercise you opened this sheath to access the common femoral artery.

The femoral sheath surrounds the common femoral artery and vein, with the region medial to the sheath containing the lower limb lymphatic vessels. The lymphatics are a series of vessels/nodes that cannot be identified unless the individual has inflamed lymph nodes.

10. Dissect into the fascia lateral to the common femoral artery to identify branches of the femoral nerve.
    (Figure528) (Netter490) (Photo5061)

The femoral nerve starts branching almost immediately as it exits deep to the inguinal ligament into the anterior thigh. These branches will innervate each of the muscles of the anterior compartment.

We won't dissect these muscular branches separately, but you may encounter individual femoral nerve branches as you examine each of the muscles below.

11. Clear fascia from the dissection area and identify the borders of the femoral triangle.
    (Figure528) (Netter490) (Photo5062)

The femoral triangle is an area bounded superiorly by the inguinal ligament, laterally by the sartorius muscle, and medially by the adductor longus muscle (which we will examine in steps later in the lab).

The contents of the femoral triangle are the femoral nerve, common femoral artery, common femoral vein, and lymphatic vessels. 

These are organized from lateral to medial: nerve, artery, vein, empty space, lymphatic.  A common mnemonic is the term NAVEL indicating the order of Nerve, Artery Vein, Empty space, Lymphatics.

12. Follow the common femoral artery from the inguinal ligament distally along the leg to identify the profunda femoris artery.
    (Figure529) (Netter490) (NetterBP108) (Photo5063)

The profunda femoris artery arises on the posterior side of the common femoral artery approximately 1-2 inches distal to the inguinal ligament. Thus, you will need to retract the femoral artery to observe the profunda femoris branch. 

Typically there is a change in diameter of the common femoral artery at the point the profunda branch occurs. The slightly reduced diameter vessel continues  distally along the thigh as the superficial femoral artery and the profunda femoris artery travels deeper (i.e. posterior) to the superficial femoral artery.

The profunda femoris artery along its course gives rise to numerous perforating branches that enter the posterior and medial compartments to supply the hamstring muscles with blood.

There are additional small branches arising from the common femoral artery before the larger profunda femoris branch (superficial epigastric, superficial circumflex iliac, and the superficial external pudendal). We will not be studying these.

13. Dissect along the lateral and medial sides of the profunda femoris artery for the femoral circumflex branches.
    (Figure529) (Netter490) (NetterBP108)
    (Photo5063) (Photo5064)

Lateral femoral circumflex artery - This artery typically arises as a branch from the profunda femoris artery and courses in an posterolateral direction to wrap around the posterior side of the femur. The vessel forms an anastomosis with the medial femoral circumflex artery on the posterior side of the femur.

Medial femoral circumflex artery - This artery typically arises as a branch from the profunda femoris artery close to the profunda femoris origin (but can arise from the common or superficial femoral arteries as it is somewhat more variable that the lateral). The medial femoral circumflex artery courses in a posteromedial direction to wrap around to the posterior side of the femur.

The circumflex arteries anastomose around the femoral neck from the lateral and medial side, which gives the vessel names. These are the major blood supply to the hip with the medial circumflex artery providing most of the supply.

14. Blunt dissect to free the sartorius muscle along its diagonal anterolateral to anteromedial course.
    (Figure528) (Netter490) (Netter482) (Photo5085)

The sartorius muscle attaches at the anterior superior iliac spine spanning across to the medial side of the tibia.

15. Examine the fascia lata lateral to the superior end of the sartorius muscle and cut a window into the fascia lata to isolate the tensor fasciae latae muscle attached to the iliac crest.
    (Figure530) (Netter490) (Netter484) (Photo5086)

The tensor fasciae latae muscle is surrounded by a tough fascia sheath that blends with the iliotibial tract to essentially 'encase' the muscle within the anterior aspect of the iliotibial band.

16. Follow the tensor fasciae latae muscle inferiorly to where it blends into the iliotibial tract.
    (Netter484) (Photo5086)

The iliotibial tract is a dense thickening of the fascia lata running laterally along the lower limb to the tibia.

The tensor fasciae latae muscle acting on the iliotibial tract serves to tense or stretch the fascia lata stabilizing the lower limb during walking or running (particularly during hurdling over objects). The gluteus maximus muscle also inserts into the iliotibial tract and acts in concert with the tensor fasciae latae muscle.

17. Observe the quadriceps femoris muscle group which occupies the bulk of the anterior compartment.
    (Figure530) (Figure531) (Netter482) (Netter490)
    (Photo5087)

This quadriceps muscle is subdivided into four heads which are given distinct names and will be examined below.

The four heads unite into a common tendon attached to the patella.

18. At the midline of the thigh, attached to the anterior inferior iliac spine (deep to the sartorius muscle attachment), is the rectus femoris muscle.
    (Figure531) (Netter482) (Photo5088)

The rectus femoris muscle is in the midline and is commonly wide enough to cover much of the anterior aspect of the other three quadriceps muscles. 

19. Blunt dissect to separate the rectus femoris muscle so that the muscle can be retracted laterally to observe the vastus medialis and intermedius muscles.
    (Figure531) (Netter482) (Photo5089)

Vastus intermedius muscle - As the name implies, this head lies in between the lateralis and medialis muscles (deep to the rectus femoris muscle and directly anterior to the femur).  The muscle attaches to the proximal femur and blends with the edges of the vastus medialis and lateralis muscles.

Vastus medialis muscle - This muscle is on the medial side attached to the proximal femur.

20. Retract the rectus femoris muscle medially and the iliotibial band laterally to observe the vastus lateralis muscle.
    (Figure531) (Netter482) (Netter491) (Photo5090)

Vastus lateralis muscle - This muscle attaches along the lateral side of the femur (linear aspera and greater trochanter). 

All four heads receive innervation from branches of the femoral nerve.

PROCEDURE - MEDIAL THIGH

21. Use your fingers and scissors to separate skin and the fascia lata away from the medial thigh.  
    (Photo5091)

The medial thigh is often called the adductor compartment, as all the muscles share some adduction roles in movement of the thigh.

The main nerve supply to all the muscles of the medial compartment of the thigh is the obturator nerve. As you examine the muscles any small nerve branches you see will be from the obturator nerve.

22. Remove fascia lata to expose the gracilis muscle, the most medial muscle of the compartment.
    (Figure532) (Figure533) (Netter482) (Photo5092)

The gracilis muscle attaches at the pubis and spans inferiorly along the thigh to the medial tibia. This is the most medial muscle in the thigh and often separate from the other medial compartment muscles by fat/fascia.

23. Remove fascia lateral to the gracilis muscle to clean the surface of the adductor longus muscle.
    (Figure532) (Figure533) (Netter482) (Netter490)
    (Photo5093)

The adductor longus inserts proximally on the pubis and distally on the linea aspera (long line) of the femur.

The superficial femoral artery and femoral nerve travel along the superficial side of the adductor longus muscle.

24. Push your fingers deep to the adductor longus muscle from the medial side and retract the muscle anterolaterally to observe the underlying adductor magnus muscle.
    (Figure533) (Netter491) (Netter483) (Photo5095)

Adductor magnus is the deepest and largest muscle of the compartment. It arises primarily from the ischial tuberosity. Inferiorly the muscle attaches along the entire length of the linea aspera of the femur.

Just anterior to the adductor magnus muscle is the smaller adductor brevis muscle. This is the adductor brevis muscle, however we will not dissect this specifically as it would disrupt the other muscles. (Photo5095a)

Multiple perforating holes/gaps are present along the lateral aspect of the adductor magnus muscle, although these are too deep to observe. These holes allow the perforating branches of the profunda femoris artery to pass into the posterior compartment of the thigh (i.e. the posterior compartment is supplied by the profunda femoris artery).

25. Return to the superficial femoral artery and follow the artery distally as it passes along the superficial side of the medial compartment of the thigh to where it penetrates through the distal tendon of the adductor magnus muscle.
    (Netter491) (Photo5096)

The most inferolateral tendon fibers of the adductor magnus muscle form a rounded tendon inserting into the medial epicondyle of the femur.

As the tendon forms, a 'hole' (hiatus) is left in the muscle close to the femur, the adductor hiatus. The superficial femoral vessels pass through this hiatus to emerge posterior to the knee into the popliteal fossa.

As the superficial femoral vessels pass through the adductor hiatus they are renamed the popliteal artery and vein. 

The position of the sartorius muscle helps to form a musculofascial tunnel for the femoral vessels called the adductor canal (a.k.a. the subsartorial canal, due to the position deep or 'sub' to the sartorius muscle).

CLINICAL EXERCISE - Leg Fasciotomy

26. Vascular and other types of trauma to the lower extremity have a high probability of leading to a compartment syndrome of the lower extremity, usually of the leg (rarely of the thigh). This is treated by performing a lower extremity fasciotomy.

- In this clinical exercise, you have the chance to perform the lower extremity fasciotomy technique on your donor.  For the steps to perform:
                                 ------ click here ------

PROCEDURE - LATERAL LEG

27. Reflect the skin away from the knee and leg to fully expose the region of the lateral and anterior compartments of the leg.
    (Photo5074)

28. Extend the skin incision distally across the lateral malleolus all the way to the sole of the foot to meet with where you had removed skin from the sole of the foot on the lateral side.
    (Figure525a) (Netter471) (Photo5075)

29. Using a combination of sharp and blunt dissection reflect/remove skin posterior to the lateral malleolus all the way to the calcaneus.
    (Photo5075a)

30. Using scissors to extend and spread the crural fascia from the knee to the ankle of the lateral compartment of the leg.
    (Netter510) (Photo5077)

At the ankle the lateral crural fascia thickens to form the fibular retinaculum, spanning from the lateral malleolus posteriorly to the calcaneus. This retinaculum holds the fibularis longus and brevis muscle tendons in position as they 'hook' around the malleolus. (Photo5034)

The fibular retinaculum has superior and inferior bands of fascia holding different parts of the tendons as they course to their attachment point, but we will treat it as a single entity for this course. 

31. Examine the most superficial muscle of the lateral compartment of the leg, the fibularis longus muscle.
    (Netter510) (Netter520) (Photo5077) (Photo5078)
    (iPhoto5001)

The fibularis longus muscle is located at the lateral side of the leg. It is attached to the head of the fibula and has a distal tendon that hooks posteriorly around the lateral malleolus of the ankle. 

Follow the muscle distally to observe that it 'hooks' around the lateral malleolus. (Photo5034)

The fibularis longus tendon curves around the lateral side of the foot onto the plantar surface to insert into the medial cuneiform bone (do not follow it to the plantar surface as you would damage other structures).

In older terminology this muscle is referred to as the peroneus longus muscle.

32. Retract the fibularis longus muscle and examine the deeper fibularis brevis muscle.
    (Netter511) (Netter510) (Photo5078)

The fibularis brevis muscle is a shorter/smaller muscle located deep to the fibularis longus muscle attached approximately half way down the fibula.

The fibularis brevis tendon travels with the fibularis longus tendon to hook around the lateral malleolus of the ankle before attaching to the metatarsal of the fifth (little) toe. (Photo5034)

Follow the muscle distally to the side of the foot.

In older terminology this muscle is referred to as the peroneus brevis muscle. Excessive 'pull' on this tendon can cause an avulsion injury to the little toe metatarsal bone (bone at the tendon insertion fractured away with the tendon).

Both the fibularis longus and brevis muscles are innervated by the superficial fibular nerve, which branches from the common fibular nerve as it passes around the fibular head. (Netter533)

PROCEDURE - ANTERIOR LEG

33. Using a combination of sharp and blunt dissection reflect skin anterior to the lateral malleolus over the dorsum of the foot working from lateral to medial.
    (Photo5076)

The dorsal skin of the foot is quite thin, but typically separates easily from underlying structures.

As you remove the skin, you may observe a medial to lateral venous arch. This is the dorsal venous arch linking the great saphenous vein to the small saphenous vein. Numerous small superficial veins drain the dorsum of the foot into this arch. (Netter473)

34. At the base of the toes progressively make a tangential incision lateral to medial such that the skin of the dorsum of the foot can be reflected medially.
    (Photo5076a)

The leg from the ankle to the knee should now be free of skin and superficial fascia from the previous thigh incisions all the way to the toes.

35. Use scissors to extend and spread the crural fascia from the knee to the ankle over the anterior compartment of the leg.
    (Netter511) (Photo5079)

It is common for there to be small adhesions or connections from the anterior compartment muscle bellies to the crural fascia. If these are present you can bluntly separate those to isolate the muscles from the crural fascia.

At the ankle the anterior crural fascia forms another thickening, the extensor retinaculum, spanning the fibula to tibia just proximal to the lateral and medial malleoli on the bones. Leave the extensor retinaculum intact for the moment.

The extensor retinaculum is actually comprised of multiple bands of tissue superior and inferior to the ankle joint, but we will treat it as a single entity for this course.

36. Spread the crural fascia widely to examine the anterior compartment of the leg.
    (Netter511) (Photo5079)

37. Examine the ankle joint where the vessels, nerves, and tendons of the anterior compartment structures cross into the extensor retinaculum at the dorsum of the foot. 
    (Netter521) (Netter511) (Photo5080)

From medial to lateral these are the:

- Tibialis anterior tendon
- Anterior tibial artery and vein
- Deep fibular nerve
- Extensor hallucis longus tendon
- Extensor digitorum longus tendon
- Fibularis tertius tendon (often absent)

38. Follow the tibialis anterior tendon (most medial tendon at the superior extensor retinaculum) proximally to observe the muscle attaching along the upper part of the tibia.
    (Figure534) (Netter521) (Netter511) (Photo5080)

39. Examine lateral to the tibialis anterior for the next tendon from medial to lateral, which is the extensor hallucis longus tendon and follow that tendon proximally to observe the muscle.
    (Figure534) (Netter521) (Netter511) (Photo5080)

You may need to retract the tibialis anterior muscle medially to expose the extensor hallucis longus muscle.

40. Examine lateral to the extensor hallucis longus tendon at the ankle for the next tendon, which is the extensor digitorum longus tendon, and follow that tendon proximally to observe the muscle.
    (Figure534) (Netter521) (Netter511) (Photo5080)

41. At the ankle, examine between the tibialis anterior and extensor hallucis longus tendons for the neurovascular bundle formed by the deep fibular nerve and anterior tibial vessels as they cross into the ankle.
    (Netter521) (NetterBP110) (Netter512) (Netter533)
    (Photo5081)

As the anterior tibial artery crosses onto the dorsum of the foot it changes name to the dorsalis pedis artery.

Where the anterior tibial artery courses between the tibialis anterior and extensor digitorum longus muscles onto the dorsum of the foot, the dorsalis pedis pulse can often be detected.

The dorsalis pedis artery arches across the dorsum of the foot towards the lateral side as the arcuate artery. Deep to the extensor tendons, it gives rise to common and proper dorsal digital arteries to the toes. This reinforces the plantar artery supply to the toes. These are typically too small to observe.

The deep fibular nerve arises from the common fibular nerve and continues onto the dorsum of the foot to provide sensation from the skin between the first and second digits. (Photo5040) 

CHECKLIST

Skeletal Structures

Femur
    Head
    Neck
    Greater trochanter
    Lesser trochanter
    Medial and lateral condyles

Tibia
    Medial and lateral plateaus
    Medial malleolus

Fibula
    Head
    Lateral malleolus

Soft Structures

Fascia lata

Crural fascia

Inguinal ligament

Femoral triangle

Great saphenous vein

Anterior thigh muscles
    Sartorius muscle
    Quadriceps muscles
        Rectus femoris muscle
        Vastus lateralis muscle
        Vastus intermedius muscle
        Vastus medialis muscle

Tensor fasciae latae muscle

Iliotibial tract

Medial thigh muscles
    Adductor longus muscle
    Adductor magnus muscle
    Gracilis muscle

Adductor hiatus

Femoral nerve

Common Femoral artery
    Superficial femoral artery
    Profunda femoris artery
    Medial femoral circumflex
    Lateral femoral circumflex

Lateral leg muscles and tendons
    Fibularis longus muscle
    Fibularis brevis muscle

Anterior leg muscles and tendons
    Tibialis anterior muscle
    Extensor digitorum longus muscle
    Fibularis tertius muscle
    Extensor hallucis longus muscle