Chapter V.

1. The following is the nature of the sinews of animals. The origin of these, also, is in the breast, for there is a sinew in the principal cavity of the heart itself; and that which is called the aorta is a sinewy vein, for its terminations are always sinewy, for they are not hollow, and are extensible, like the sinews which end upon the bending of the bones: for it is not the nature of sinews to be continuous from one origin, like the veins, for the veins have the whole form of the body as in outline sketches, so that in emaciated subjects the whole mass appears full of veins, for the same place is occupied by veins in lean persons that in fat ones is flesh.

2. The sinews are drawn round the joints and flexures of the bones; but, if their nature were continuous, the continuation would be evident in emaciated persons. The principal parts of the sinews are around the part of the body appropriated to leaping, and this is called the poples. Another double sinew is the tendon of the neck, and the epitonus and the sinew of the shoulder, which aid in the support of the body. The sinews around the joints have not received any name, for all the bones where they are contiguous are bound together by the sinews.

3. And there are many sinews round all the bones; there are none in the head; but the sutures of the skull are adapted to each other. It is the nature of sinew to tear readily lengthwise, but across the fibre it is indivisible, and it is very extensible. The sinews are surrounded by a mucous, white, and gelatinous fluid, by which they are nourished, and from which they seem to derive their origin. The vein does not alter its form by combustion, but the sinew is entirely destroyed. Neither does it unite after division.

4. Numbness does not take place in those parts of the body which contain no sinews. The sinews are most abundant on the hands and feet, and on the ribs and shoulder-blades, and round the neck and arms. All sanguineous animals have sinews; but in those which have not jointed limbs, and are without feet and hands, the sinews are small and inconspicuous, so that in fishes they are most distinct near the fins.