Learning Objectives:
Upon completion of this session, the student will be able to:
- Describe the subcutaneous venous drainage of the lower limb, its relation to the deep veins and the significance of perforating veins.
- Describe the lymphatic drainage of the lower limb and areas draining into the superficial and deep inguinal lymph nodes.
- Identify the major cutaneous nerves of the lower limb, their source and the areas they innervate.
- Define the regional deep fascias of the lower limb and their regional specialization such as iliotibial tract, etc.
Learning Objectives and Explanations:
1. Describe the subcutaneous venous drainage of the lower limb, its relation to the deep veins, and the significance of perforating veins. (W&B 577-579, N 544,545, TG 3-02,3-03)
The superficial veins of the lower limb begin as the dorsal venous arch of the foot. This dumps into two primary veins:
greater saphenous vein: on the medial side. It receives blood from the dorsal venous arch. The greater saphenous vein then heads north, traveling anterior to the medial malleolus, up the leg, through the knee region on the posterior aspect of the medial condyle of the femur, then turns anteriorly and laterally as it travels up the thigh. The greater saphenous vein travels through the saphenous opening, a passageway in the fascia of the femoral triangle, to drain into the femoral vein. Along its course the greater saphenous vein receives tributaries from the dorsum of the foot, the heel, the front of the leg, and anterior, medial, and lateral portions of the thigh. Also important, right before emptying into the femoral vein, the greater saphenous vein receives the superficial epigastric, superficial circumflex iliac, and superficial external pudendal veins.
lesser saphenous vein: on the lateral side. It runs posterior to the lateral malleolus and up the middle of the back of the leg. It usually pierces the crural fascia about halfway up the leg, running the rest of the way deep to the fascia. In most cases, the lesser saphenous vein terminates in the popliteal vein.
Images from "Anatomy of the Human Body" by Henry Gray are provided by: 
2. Describe the lymphatic drainage of the lower limb and areas draining into the superficial and deep inguinal lymph nodes. (W&B 578-580, N 546, TG 3-70)
The superficial lymph vessels of the lower limb accompany the superficial veins. They end in the superficial inguinal lymph nodes. From there, most lymph passes directly to the external iliac lymph nodes, but some flows to the deep inguinal lymph nodes. The deep lymphatic vessels accompany the deep veins, and drain directly into the deep inguinal lymph nodes.
3. Identify the major cutaneous nerves of the lower limb, their source, and the areas they innervate. (W&B 580-583, N 540, 541, 542, 544, TG 3-68,3-44,3-48,3-69A,3-69B)
The figures on W&B 581 and N543 or TG3-69A and TG3-69B are handy views of dermatomes of the lower limb, though they don't technically show how the fibers get there, i.e., via which nerve. But, if you check out W&B 582, and N540, N542, N544, TG3-63, N542, TG3-64, TG3-65A,TG3-65B,TG3-66,TG3-67, or check out the images below, you'll get the idea.
Images from "Anatomy of the Human Body" by Henry Gray are provided by:
Images from "Anatomy of the Human Body" by Henry Gray are provided by:
knee and above:
- subcostal nerve: from T12. Supplies the skin of the thigh over greater trochanter of femur.
- iliohypogastric nerve: from L1 (lumbar plexus). The lateral cutaneous branch supplies the skin of the superolateral buttock, while the anterior cutaneous branch supplies the skin superior to pubis.
- ilioinguinal nerve: from L1 (lumbar plexus). Branches supply the skin of the proximal, medial thigh, near the external genitalia.
- genitofemoral nerve: from L1 and L2 (lumbar plexus). Femoral branches supply the skin of the proximal, anterior thigh, just inferior to inguinal ligament.
- lateral femoral cutaneous nerve: from L2 and L3 (direct branch of the lumbar plexus). Anterior branches supply the skin of the lateral and anterior thigh. The posterior branch supplies the skin of the thigh from the greater trochanter to just proximal to the knee.
- anterior femoral cutaneous nerves: from the femoral nerve (L2 through L4, lumbar plexus). Supply to the skin of the medial and anterior thigh.
- obturator nerve: (L2 through L4, lumbar plexus). A branch (variable) sometimes supplies the skin of the medial aspect of the proximal thigh.
- posterior femoral cutaneous nerve: from S1 through S3 (sacral plexus). Supplies the skin of the lower buttock, posterior thigh, and the skin of the posterior knee.
below the knee:
- saphenous nerve: from the femoral nerve (L2 through L4, lumbar plexus). Supply to the skin of the anterior and medial side of the leg and the medial side of the foot.
- sural nerve: from both tibial and common fibular nerves (which come from the sciatic nerve, L4 through S3): Supplies the skin on the posterior and lateral aspects of the leg and lateral side of the foot.
- lateral sural cutaneous nerve: from the common fibular nerve (which comes from the sciatic nerve, L4 through S3): Supplies the skin of the posterolateral leg.
- superficial fibular nerve: from the common fibular nerve (which comes from the sciatic nerve, L4 through S3): Supplies the skin of the inferior third of the anterior leg and the dorsal part of the foot.
4. Define the regional deep fascias of the lower limb and their regional specializations. (W&B 584-588, 608-610, N 509,522,530, TG 3-02,3-03,3-45)
The deep fascia of the lower limb is called the fascia lata in the thigh and the crural fascia in the leg. These have the following specializations:
fascia lata:
- iliotibial tract: a thickening of the fascia lata that stretches from the tubercle of the crest of the ilium to attach to the lateral condyle of the tibia. Serves as insertion point for the tensor fascia lata and part of the insertion for the gluteus maximus.
- lateral intermuscular septum: from the iliotibial tract to the lateral epicondylar line and the lateral lip of the linea aspera, both on the femur. It separates the vastus lateralis muscle from the biceps femoris muscles, therefore separating the quadriceps group from the hamstrings.
- medial intermuscular septum: attaches to the medial lip of the linea aspera of the femur. It separates the vastus medialis muscle (quadriceps) from the adductor group (medial) of muscles.
- saphenous opening (hiatus): a passageway through the fascia lata for the great saphenous vein.
crural fascia:
- retinacula of the patella: formed by the attachments of the crural fascia to the medial and lateral condyles of the tibia and the head of the fibula. This also includes tendinous fibers from the vastus muscles. (Latin, retinacula = halter, cable)
- anterior intermuscular septum: from the crural fascia to the anterior aspect of the fibula. It separates the anterior (extensor) muscles from the lateral (fibular) muscles. Also, one could say that it is the boundary between the anterior and lateral compartments.
- posterior intermuscular septum: from the crural fascia to the posterior aspect of the fibula. It separates the posterior (flexor) muscles from the lateral (fibular) muscles. Also, one could say that it is the boundary between the posterior and lateral compartments.
- transverse intermuscular septum: from the posterior intermuscular septum, around to the anteromedial aspect of the tibia. It separates the deep posterior muscles from the superficial posterior muscles.
- popliteal fascia: two layers, superficial and deep, that cover the popliteal fossa. This fascia stretches with the movement of the knee joint, providing protection for the neurovascular structures traveling through the area.
In the ankle region, the crural fascia thickens to form retinacula that hold tendons close to the bone, creating a sort of pulley sytem. They are listed here:
- superior extensor retinaculum: superior to the ankle, on the anterior aspect of the leg
- inferior extensor retinaculum: on the anterior aspect of the ankle. It is Y-shaped, extending onto the dorsum of the foot.
- flexor retinaculum: on the posteromedial aspect of the ankle
- superior and inferior fibular retinacula: on the posterolateral aspect of the ankle
Questions and Answers:
5. Do you see accessory tributaries or varicosities of the superficial veins?
There is usually a fairly large accessory saphenous vein draining the medial thigh, in addition to numerous smaller accessory tributaries. The superficial veins communicate with the deep veins of the lower limb via perforating veins through the deep fascia of the lower limb. These perforating veins have valves that direct the blood superficial to deep as the result of limb motions and muscle contractions. However, the valves may become incompetent, resulting in retrograde blood flow from deep to superficial. The superficial veins may become dilated and torturous, especially in the leg.
6. To what vein does the greater saphenous vein drain?
The greater saphenous vein drains to the femoral vein, through the saphenous hiatus. N544,TG3-02
7. From what regions do the superficial inguinal lymph nodes receive lymph?
The superficial inguinal lymph nodes receive lymph from the superficial tissues of lower abdominal wall, the external genitalia, the perineum, the buttocks, and the lower limb. N546,TG3-70
8. Where do the superficial inguinal lymph nodes drain?
They drain primarily to external iliac lymph nodes, but some drain to the deep inguinal lymph nodes.
9. Where would you find the deep inguinal lymph nodes?
The deep inguinal lymph nodes, approximately three in number, lie within the femoral canal, within the femoral sheath, medial to the femoral vein. N546,TG3-70
10. What is the distribution of the femoral branch of genitofemoral nerve?
This small branch of the genitofemoral nerve within the abdomen passes beneath the inguinal ligament on the external iliac artery. It innervates a small area of skin on the upper medial thigh. N544,TG3-02
11. From what are the cutaneous nerves of the anterior thigh derived?
The lateral femoral cutaneous nerve is from the lumbar plexus, specifically L2 and L3. The anterior femoral cutaneous nerves are branches of femoral nerve. The femoral branch of genitofemoral nerve is from the lumbar plexus, specifically L1 & L2. N544TG3-14
12. What is the source of the saphenous nerve?
The femoral nerve is the source of the saphenous nerve. N545,TG3-24
13. What nerves accompany the lesser saphenous vein?
The medial sural cutaneous nerve and sural nerve accompany the lesser saphenous vein. N538,TG3-03
14. Where does the lesser saphenous vein disappear? Where does it terminate?
The lesser saphenous vein pierces the popliteal fascia covering the popliteal fossa at the back of the knee. In that area it drains into the popliteal vein. N545,TG3-03,TG3-33
15. How is the sural nerve formed?
The sural nerve is formed from fibers contributed by both the tibial and common fibular nerves. N545,TG3-03
16. Where does the sural nerve distribute and by what name?
It distributes to the posterolateral aspect of the lower leg, the ankle, and the heel. Its continuation on the lateral side of the foot, all the way down to the little toe, is called the lateral dorsal cutaneous nerve. N545,TG3-03,TG3-44
