the artery.

The branches derived from the popliteal artery are the muscular and the
articular. The former spring from the vessel opposite those parts of the
several muscles which lie in contact with it; the latter are generally
five in number--two superior, two inferior, and one median. The two
superior articular branches arise from either side of the artery, and
pass, the one beneath the outer, the other beneath the inner flexors,
above the knee-joint; and the two inferior pass off from it, the one
internally, the other externally, beneath the heads of the gastrocnemius
below the joint; while the middle articular enters the joint through the
posterior ligament. The two superior and inferior articular branches
anastomose freely around the knee behind, laterally, and in front, where
they are joined by the terminal branches of the anastomotic, from the
femoral, and by those of the recurrent, from the anterior tibial. The
main vessel, having arrived at the lower border of the popliteus muscle,
divides into two branches, of which one passes through the interosseous
ligament to become the anterior tibial; while the other, after
descending a short way between the bones of the leg, separates into the
peronaeal and posterior tibial arteries. In some rare instances the
popliteal artery is found to divide above the popliteus muscle into the
anterior, or the posterior tibial, or the peronaeal.

The two large muscles, (gastrocnemius and soleus,) forming the calf of
the leg, have to be removed together with the deep fascia in order to
expose the posterior tibial, and peronaeal vessels and nerves. The
fascia forms a sheath for the vessels, and binds them close to the deep
layer of muscles in their whole course down the back of the leg. The
point at which the main artery, F, Plate 66, gives off the anterior
tibial, is at the lower border of the popliteus muscle, on a level with
N, the neck of the fibula; that at which the artery again subdivides
into the peronaeal, P, and posterior tibial branches, O, is in the
mesial line of the leg, and generally on a level with the junction of
its upper and middle thirds. From this place the two arteries diverge in
their descent; the peronaeal being directed along the inner border of
the fibula towards the back of the outer ankle; while the posterior
tibial, approaching the inner side of the tibia, courses towards the
back of the inner ankle. The gastrocnemius and soleus muscles overlie
both arte