CHAP. III. Of the Broade Muscle.
NOw we should prosecute the containing parts of the face, to wit the skin, the fleshy pannicle and fat; but because they have beene spoken of suffici∣ently before, I will onely describe the sleshy pannicle, before I come to the dissection of the eye, that wee may the more easily understand, all the motions performed by it, whether in the face or forehead.
First that you may more easily see it, you must curiously separate the skin in some part of the face. For unlesse you take good heed, you will pluck away the fleshy pan∣nicle together with the skinne, as also this broad muscle to which it immediatly ad∣heres, and in some places so closly and firmely, as in the lips, eye-lids and the whole forehead, that it cannot be separated from it. Nature hath given motion, or a move∣ing force to this broad muscle, that whilest it extends, or contracts it selfe, it might serve to shut and open the eye. It will be convenient to separate the muscle thus freed from the skin, beginning from the forepart of the clavicles even to the chin, ascend∣ing in a right line, and then turning backe as far as you can; for thus you shall shew how it mixes it selfe with the skinne and the muscles of the lips.
When thou shalt come to the Eyes, thou shalt teach how the eye is shut and opened by this one muscle, because it is composed of the three sorts of fibers; although by * 1.1 the opinion of all who have hitherto written of Anatomy, those actions are said to be performed by the power of two muscles appointed for that purpose; one of which is at the greater corner on the upper part, the other resembling a semicircle at the lesser corner, from whence extending it selfe to the midle of the gristle Tarsus, it meets with the former ending there, but they are in part extended over all the eyelid, whereby it commeth to passe that it also in some sort becometh moveable. But al∣though in publike dissections these two muscles are commonly wont to be solemnly shewed, after the manner I have related; yet I thinke, that those which shew them know no more of them, than I doe. I have grounded my opinion from this, that there appeares no other musculous flesh in these places, to those which separate the fleshy pannicle, or broad muscle, than that which is of the panicle it selfe, whether you draw your incision knife from the forehead downewards, or from the cheeke upwards.
Besides when there is occasion to make incision on the eye-browes, we are forbid∣den to doe it transverse, least this broad muscle falling upon the eye, make the up∣per * 1.2 Eye-lid unmoveable: but if such a cut be received accidentally, we are comman∣ded presently to stitch it up; which is a great argument that the motion of the upper eye-lid is not performed by its proper muscles, but wholy depends and is perform∣ed by the broad muscle. Now if these same proper muscles which we have described should be in the upper eye-lid, it should be meet, (because when one of the muscles is in action, the other which is its opposite or Antagonist, rests or keeps holieday,) that when that which is said to open the eye is imployed, the opposite thereof resting, the * 1.3 upper eye-lid should be drawne towards its originall, as we see it happens in convul∣sions: because the operation of a muscle is the collection of the part which it moves towards its originall.