İKİNCİ FEN · ÜÇÜNCÜ BÂB · ÜÇÜNCÜ FASIL · Beşinci Madde
Fifth Article
Concerning the muscles and movements of the knee joint.
O, esteemed one! Know that anatomists have said: There are three muscles which move the knee joint, situated on the front side of the thigh. These are among the largest and most beautiful of the muscles found in the thigh. Their function is to open [extend]. One of these three muscles appears double, having two bodies; one originates from the *zā’ida-i kubrā* [greater sciatic muscle] and the other from the front of the thigh. One of these two bodies is fleshy, attached to the anterior surface of the kneecap without a tendon. The other is membranous, terminating within the inner sides of the thigh. The remaining two muscles are explained with those that open the thigh. It is known that one originates from the septal membranes separating some cavities in the pelvic bone. The second originates from the outer *zā’ida* [sciatic muscle], encircling the kneecap and proceeding to protect the parts beneath it. From there, it reaches the tibia and extends the tibia to open the knee.
A broad adductor muscle also arises from where the pubic bone joins, descends obliquely inwards along the inner side of the thigh. Its aspect towards the upper part of the calf enters inward, drawing and extending the calf toward its inner side. Another adductor’s origin is from the ischial tuberosity, descending at an angle on the outer side to meet the aforementioned muscle. From there it turns and goes into the deeper region, rotating and opening the leg outwards. If these two muscles contract together, the calf extends straight.
One of the muscles that flexes the calf is a slender, long muscle which originates from the pelvis and pubic bones, near the origin of the muscle drawing the leg inward, and close to the septal membranes separating the cavities in the middle of the pelvic bone. From there it enters obliquely towards both sides of the knee and exits again from there. The portion entering goes as far as the knee and extends to the toes. There are three more muscles; one on the inner side, one on the outer side, and one in the middle, which with the muscle on the outer side and the muscle in the middle, turn and flex the calf outwards. It is known that the muscle on the inner side bends the calf towards its own side with an inclination inward. The origin of the inner muscle is from the base of the ischial tuberosity, descending at an angle as far as the end of the leg, until it reaches and attaches to the hollow place on the inside of the leg; its color tends toward green. The origins of the muscles on the outer side and in the middle are also from the base of the ischial tuberosity, from which they originate. But when these two reach their termination, they incline outwards. There is a muscle embedded in the concavity of the knee joint that assists in the movement of the central muscle. Thus, one who observes these exalted arts will be astonished and return to himself, observing these wondrous wisdoms. Knowledge of recognizing the body leads to knowledge of recognizing the self (marifa-i nafs).