This section is from the book "Anatomy Of The Arteries Of The Human Body", by John Hatch Power. Also available from Amazon: Anatomy of the Arteries of the Human Body, with the Descriptive Anatomy of the Heart.
The Superior Internal Articular Artery arises under cover of the semi-membranosus muscle; it runs upwards and forwards and arches over the internal condyle of the femur, between that bone and the tendon of the adductor magnus; it terminates in two branches, one of which supplies the vastus internus, and the other is lost on the inside of the knee-joint: it anastomoses with the inferior internal articular artery, and with the anastomotic. Two superior internal articular arteries have been described, but one of them is that which has been mentioned already as the anastomotica magna branch of the femoral.
The Superior External Articular Artery passes upwards and outwards and arches over the external condyle of the femur, between that bone and the biceps tendon. It terminates in two branches, one of which supplies the vastus externus muscle, while the other is lost on the outside of the joint. It communicates with the anastomotic, with the external circumflexa femoris, and with the inferior external articular artery.
The Inferior Internal Articular Artery, larger than the external, runs downwards and inwards, along the superior margin of the popliteus muscle, then winds round the inside of the neck of the tibia, covered by the inner head of the gastrocnemius, by the internal lateral ligament, and by the tendons of the sartorius, gracilis, and semi-tendinosus muscles. It is lost in the structures on the inner side and front of the joint.