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6c. The Popliteal Artery
FIG. 552 - Circumpatellar anastomosis. (A. Poplitea)
The popliteal artery (Fig. 551) is the continuation of the femoral, and courses through the popliteal fossa. It extends from the opening in the Adductor magnus, at the junction of the middle and lower thirds of the thigh, downward and lateralward to the intercondyloid fossa of the femur, and then vertically downward to the lower border of the Popliteus, where it divides into anterior and posterior tibial arteries.Relations.—In front of the artery from above downward are the popliteal surface of the femur (which is separated from the vessel by some fat), the back of the knee-joint, and the fascia covering the Popliteus. Behind, it is overlapped by the Semimembranosus above, and is covered by the Gastrocnemius and Plantaris below. In the middle part of its course the artery is separated from the integument and fasciæ by a quantity of fat, and is crossed from the lateral to the medial side by the tibial nerve and the popliteal vein, the vein being between the nerve and the artery and closely adherent to the latter. On its lateral side, above, are the Biceps femoris, the tibial nerve, the popliteal vein, and the lateral condyle of the femur; below, the Plantaris and the lateral head of the Gastrocnemius. On its medial side, above, are the Semimembranosus and the medial condyle of the femur; below, the tibial nerve, the popliteal vein, and the medial head of the Gastrocnemius. The relations of the popliteal lymph glands to the artery are described above. Peculiarities in Point of Division.—Occasionally the popliteal artery divides into its terminal branches opposite the knee-joint. The anterior tibial under these circumstances usually passes in front of the Popliteus. Unusual Branches.—The artery sometimes divides into the anterior tibial and peroneal, the posterior tibial being wanting, or very small. Occasionally it divides into three branches, the anterior and posterior tibial, and peroneal. Branches.—The branches of the popliteal artery are: Muscular Superior Lateral Superior Genicular. Sural. Middle Genicular. Cutaneous. Medial Inferior Genicular. Medial Superior Genicular Lateral Inferior Genicular. The superior muscular branches, two or three in number, arise from the upper part of the artery, and are distributed to the lower parts of the Adductor magnus and hamstring muscles, anastomosing with the terminal part of the profunda femoris. The sural arteries (aa. surales; inferior muscular arteries) are two large branches, which are distributed to the Gastrocnemius, Soleus, and Plantaris. They arise from the popliteal artery opposite the knee-joint. The cutaneous branches arise either from the popliteal artery or from some of its branches; they descend between the two heads of the Gastrocnemius, and, piercing the deep fascia, are distributed to the skin of the back of the leg. One branch usually accompanies the small saphenous vein. The superior genicular arteries (aa. genu superiores; superior articular arteries) (Figs. 550, 551), two in number, arise one on either side of the popliteal, and wind around the femur immediately above its condyles to the front of the knee-joint. The medial superior genicular runs in front of the Semimembranosus and Semitendinosus, above the medial head of the Gastrocnemius, and passes beneath the tendon of the Adductor magnus. It divides into two branches, one of which supplies the Vastus medialis, anastomosing with the highest genicular and medial inferior genicular arteries; the other ramifies close to the surface of the femur, supplying it and the knee-joint, and anastomosing with the lateral superior genicular artery. The medial superior genicular artery is frequently of small size, a condition, which is associated with an increase in the size of the highest genicular. The lateral superior genicular passes above the lateral condyle of the femur, beneath the tendon of the Biceps femoris, and divides into a superficial and a deep branch; the superficial branch supplies the Vastus lateralis, and anastomoses with the descending branch of the lateral femoral circumflex and the lateral inferior genicular arteries; the deep branch supplies the lower part of the femur and knee-joint, and forms an anastomotic arch across the front of the bone with the highest genicular and the medial inferior genicular arteries. The middle genicular artery (a. genu media; azygos articular artery) is a small branch, arising opposite the back of the knee-joint. It pierces the oblique popliteal ligament, and supplies the ligaments and synovial membrane in the interior of the articulation. The inferior genicular arteries (aa. genu inferiores; inferior articular arteries) (Figs. 550, 551), two in number, arise from the popliteal beneath the Gastrocnemius. The medial inferior genicular first descends along the upper margin of the Popliteus, to which it gives branches; it then passes below the medial condyle of the tibia, beneath the tibial collateral ligament, at the anterior border of which it ascends to the front and medial side of the joint, to supply the upper end of the tibia and the articulation of the knee, anastomosing with the lateral inferior and medial superior genicular arteries. The lateral inferior genicular runs lateralward above the head of the fibula to the front of the knee-joint, passing in its course beneath the lateral head of the Gastrocnemius, the fibular collateral ligament, and the tendon of the Biceps femoris. It ends by dividing into branches, which anastomose with the medial inferior and lateral superior genicular arteries, and with the anterior recurrent tibial artery. The Anastomosis Around the Knee-joint (Fig. 552).—Around and above the patella, and on the contiguous ends of the femur and tibia, is an intricate net-work of vessels forming a superficial and a deep plexus. The superficial plexus is situated between the fascia and skin around about the patella, and forms three well-defined arches: one, above the upper border of the patella, in the loose connective tissue over the Quadriceps femoris; the other two, below the level of the patella, are situated in the fat behind the ligamentum patellæ. The deep plexus, which forms a close net-work of vessels, lies on the lower end of the femur and upper end of the tibia around their articular surfaces, and sends numerous offsets into the interior of the joint. The arteries which form this plexus are the two medial and the two lateral genicular branches of the popliteal, the highest genicular, the descending branch of the lateral femoral circumflex, and the anterior recurrent tibial.
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