CHAP. IV. Of the Cranium, or Skull.
THe Cranium, or Skull covering the Brain like an Helmet,* 1.1 is composed and consists of se∣ven Bones; of which some are more dense, thick and hard than othersome. The first is the Os Occipitis, or Nowl-bone seated in the Back-part of the head,* 1.2 more hard and thick than the rest, because we want hands and eyes behind, whereby we may keep or save our selves from falling.
This Bone is circumscribed, or bounded by the suture Lambdoides, and the* 1.3 Os basilare. The eminencies, and, as it were, heads of this Bone are received into the first Vertebra; for upon this the head is turned forwards and backwards, by the force of fourteen muscles and strong liga∣ments, which firmly tie these heads of the Nowl-bone in the cavities of this first vertebra.
The second Bone of the skull is in the forepart, and is called the Os Coronale, or Os frontis, the fore-head-bone; it hath the second place in strength and thickness. It is bounded by the Coro∣nal suture, and the ends of the wedg-bone: in this forehead-bone there is often found a great ca∣vity under the upper part of the eye-brows, filled with a glutinous, gross, viscid and white mat∣ter or substance, which is thought to help to elaborate the air for the sense of smelling.
Chirurgeons must take special notice of this cavity; because when the head chances to be broken in that place, it may happen, that the fracture exceeds not the first table; wherefore being ignorant of this cavity, and moved with a false perswasion that they see the Brain, they may think the Bone wholly broken, and to press the Meninges, whereupon they will dilate the womb, and apply a Trepan and other instruments to lift up the second table of the Bone, without any need at all, and with the manifest danger of the life of the Patient.
The third and fourth Bones of the skull, are the Ossa parietalia, or Bregmatis,* 1.4 having the third place of density and thickness; although this density and thickness be different in divers places of them. For on the upper part of the head, or crown, (where that substance turns not to a Bone in children, until they have all their teeth, so that it feels soft in touching, and through it you may feel the beating of the Brain) these Bones are very tender, so that oft-times, they are no thicker than ones nail, that so the moist and vaporous excrements of the Brain, shut up where the greater portion of the Brain resides, may have a freer passage by the Brain's Diastole and Systole. These two square Bones are bounded above with the Sagittal suture, below with the scaly, on the fore-part with the coronal, and on the hind-part with the Lambdoides.
The fifth and sixth Bones of the skull, are the two Ossa Petrosa, stony or scaly Bones,* 1.5 which are next to the former in strength. They are bounded with the false or bastard-Suture, and with part of the Lambdoides, and wedg-bone.
The seventh is the Os sphenoides, basilare, or Cuneiforme, that is, the wedg-bone.* 1.6 It is called Basi∣lare, because it is (as it were) the basis of the head. To this the rest of the Bones of the head are fit∣ly fastned in their places. This Bone is bounded on each side with the Bones of the forehead, the stony Bones, and Bones of the Nowl and Palat. The figure represents a Bat, and its processes her wings.
There is besides these another Bone at the basis of the forehead-bone,* 1.7 into which the mamillary processes end; the Greeks call it 〈 in non-Latin alphabet 〉〈 in non-Latin alphabet 〉, the Latins, Cribrosum and Spongiosum, the spongy-Bone; because it hath many holes in it not perforated in a direct passage, as in a sive, but winding and an∣fractuous, that the air should not by the force of attraction, presently leap or ascend into the brain,* 1.8 and affect it with its qualities, before it be elaborated by its lingring in the way. There are besides also, six other little Bones lying hid in the stony Bones at the hole or auditory-passage; on each side three, that is to say, the Incus or Anvil, the Malleolus or Hammer, and the Stapes or stirrop, be∣cause in their figure they represent these three things; the use of these we will declare hereafter.
But also in some skulls there are found some divisions of Bones, as it were collected fragments, to the bigness almost of ones thumb, furnished and distinguished by their proper commissures, or sutures, which thing is very fit to be known to a Chirurgion in the use of a Trepan.* 1.9
Verily he may give a conjecture hereof, whilst he separates the pericranium from the skull, for the pericranium is with greater difficulty pluckt away from the sutures, because the Crassa meninx hath straiter connexion therewith by his nervous fibers sent forth in such places. The skulls in women are softer and thinner than in men, and in children more than in women, and in young men more than in men of a middle age. Also the Aethiopians or Black-moors, as also all the peo∣ple inhabiting to the South, have their skulls more hard and composed with fewer sutures.
Therefore, as it is written by Hippocrates, such as have their Skulls the softer, the Symptoms in fractures, are more dangerous and to be feared in them. But the Skull by how much the softer it is, by so much it more easily and readily yields to the perforating Trepan. Moreover in some skulls, there be bunches standing out besides nature, made either round or cornered,