MRCS Part B (OSCE) - Online Resources

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• The lower leg has superficial veins in the subcutaneous tissue and also deep veins which lie beneath the deep fascia, within the muscle, and usually accompany the named arteries.
• Both the superficial and deep veins have valves.
• The main superficial veins are the long (great) and short (small) saphenous veins.
• Perforating veins pierce the deep fascia. They drain blood from the superficial veins to the deep veins which are subject to compression as muscles contract deep to the fascia.

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• The long (great) saphenous vein is formed by the union of the dorsal vein of the great toe and the medial limb of the dorsal venous arch of the foot.
• Ascends 2 cms anterior to the medial malleolus along the medial border of the tibia and approximately a hands breadth medial to the medial border of the patella.
• Then lies posterior to the medial condyle of the femur and runs along the medial side of the thigh. It empties into the sapheno-femoral junction (fossa ovalis) after piercing the cribriform fascia (the layer of fascia lata in this region).
• The sapheno-femoral junction lies 4 cm below and lateral to the pubic tubercle.
• From the medial malleolus up to the apex of the femoral triangle, the long saphenous vein lies in close proximity to the saphenous nerve.
• Below the knee joint it receives numerous tributaries and forms anastomoses with the small saphenous vein.
• At the sapheno-femoral junction it receives other small tributaries including the superficial circumflex iliac, superficial epigastric and external pudendal veins.

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• The short (small) saphenous vein arises on the lateral aspect of the foot from the union of the dorsal vein of the little toe and the lateral limb of the dorsal venous arch.
• It ascends posteriorly to the lateral malleolus, passes along the lateral border of the Achilles tendon ascending in the superficial fasica between the two heads of gastrocnemius and terminates by draining into the popliteal vein in the popliteal fossa.

• The sapheno-popliteal junction lies in the midline of the popliteal fossa, approximately 2 cm above or 2 cm below the joint line.
• Similar to the saphenous nerve accompanying the long saphenous vein, the sural nerve accompanies the short saphenous vein from the popliteal fossa to the lateral malleolus.
• The popliteal vein ascends through the adductor hiatus to enter the Hunter’s canal and continues as the femoral vein.

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An understanding of the venous anatomy is clinically significant for surgeons performing:

• Sapheno-venous cut-down during an emergency.
• Varicose vein surgery.
• Harvest of a vein graft:, i.e., during vascular or cardiothoracic surgery.
• During sural nerve grafting for during reconstructive procedures, it is important to know the course of the short saphenous vein to prevent inadvertent injury.

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"Valves usually prevent flow from the deep veins through the perforating veins into the superficial system. If they become incompetent, blood flows into the superficial venous system and as a result, the superficial veins become tortuous and dilated. They then present as varicose veins. "

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Saphenous vein graft is suitable for coronary arterial bypass as it is:

• Lies in the superficial fascia and is therefore easily accessible.
• Has a consistent anatomical course.
• The walls have high content of muscular and elastin fibres suitable for coronary artery grafting.
• Sufficient length can be harvested due to adequate distance between tributaries and perforating veins.

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"The saphenous nerve accompanies the long saphenous vein anterior to the medial malleolus and is vulnerable during saphenous venous cut-down. "

"The patient presents with loss of sensation along medial border of the lower leg, ankle and foot. Since the saphenous nerve is purely sensory, the patient will not have any motor deficit. "

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• The femoral artery lies lateral to the femoral vein in the femoral triangle.
• The long saphenous vein receives several tributaries in the region of the saphenous opening whereas the femoral vein only receives the saphenous vein.
• The long saphenous vein is more superficial than the femoral vein.

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• The lower limb is drained by superficial and deep lymphatic vessels.
• The superficial lymphatics accompany the saphenous veins and their tributaries.
• Those accompanying the long saphenous vein end at the superficial inguinal lymph nodes.
• Most lymph from these nodes then passes directly to the external iliac lymph nodes located along the external iliac vein but may also pass to the deep inguinal lymph nodes.
• The lymphatic vessels accompanying the short saphenous vein enter the popliteal lymph nodes which lie deep in the popliteal fossa.
• The deep lymphatic vessels from the leg accompany the deep veins and enter the popliteal lymph nodes.
• Most lymph from these noes ascends through deep lymphatic vessels to the deep inguinal lymph nodes. These lie beneath the deep fascia medial to the femoral vein in the femoral triangle. Lymph from these nodes drain to the external iliac lymph nodes.

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Some common causes of regional inguinal lymphadenopathy include:
Infection
 Localised infection of the lower limb, perineum or external genitalia.
 Dermatitis.
 Parasitic infections such as filariasis.
 Syphilis.
 Lymphogranuloma venereum.

Malignancy
 Tumours (such as SCC or malignant melanoma) from the entire lower limb and perineum.
Note: The possibility of metastases from a carcinoma of the uterus should also be considered in females as some lymphatic drainage from the uterine fundus may drain to the superficial inguinal lymph nodes.

Complications following lymph node dissection include:
 General:
 Pain.
 Infection.
 Bleeding.
 Haematoma.
 Oedema.
 Wound dehiscence.
 Scar.
 Specific:
 Injury to the femoral vessels or nerve.
 Numbness.
 Seroma.
 Lymphoedema