Book 1
7
Wherefore, the parts are sometimes paralysed singly, as one eye-brow, or a finger, or still larger, a hand, or a leg; and sometimes more together; and sometimes the right or the left only, or each by itself, or all together, either entirely or in a less degree; and the parts only which are distant, homonymous, and in pairs—the eyes, hands, and legs; and also the parts which cohere, as the nose on one side, the tongue to the middle line of separation, and the one tonsil, the isthmus faucium, and the parts concerned in deglutition to one half. I fancy, also, that sometimes the stomach, the bladder, and the rectum, as far as its extremity, suffers in like manner; but the internal parts, when in a paralytic state, are concealed from the sight. Their functions, however, are but half performed; and from this I conclude, that these parts are half affected, as being cut in twain by the disease. And, indeed, this thing teaches us a lesson in respect to the diversity of power and discrimination between the right side and the left. For the inherent cause is equal; and means which occasion the affection are common in both cases, whether cold or indigestion, and yet both do not suffer equally. For Nature is of equal power in that which is equally paired; but it is impossible that the same thing should happen where there is an inequality. If, therefore, the commencement of the affection be below the head, such as the membrane of the spinal marrow, the parts which are homonymous and connected with it are paralysed: the right on the right side, and the left on the left side. But if the head be primarily affected on the right side, the left side of the body will be paralysed; and the right, if on the left side. The cause of this is the interchange in the origins of the nerves, for they do not pass along on the same side, the right on the right side, until their terminations; but each of them passes over to the other side from that of its origin, decussating each other in the form of the letter X. To say all at once, whether all together or separate parts be affected with paralysis ..... or of both; sometimes the nerves from the head suffer (these, generally, induce loss of sensibility, but, in a word, they do not readily occasion loss of sensibility; but if they sympathise with the parts which are moved, they may undergo, in a small degree, the loss of motion); and sometimes those which pass from muscle to muscle (from the spinal marrow to the muscles),See the note on the text. these have the power of motion, and impart it to those from the head; for the latter possess the greater part of their motory power from them, but yet have it, to a small extent, of themselves: the former, too, principally suffer loss of motion, but rarely of themselves experience anæsthesia; indeed, as appears to me, not at all. And if the ligaments of nerves, which derive their origin from certain of the bones, and terminate in others, be loosened or torn, the parts become powerless, and are impeded in their movements, but do not become insensible.It will readily be understood that our author here refers to the ligaments proper of the joints. On this use of the term Nerve, see Hippocrates On the articulations, pluries.
