What difference is there between the true and spurious Sutures.
The true Sutures are made in form of the Teeth of a Saw, which enter one into the other; and the false or Bastard ones are those that resemble the Scales of Fishes, which
are join'd together by passing one over the other.
What is the Use of the Sutures?
The Ancients were of Opinion, that they were made to hinder the Fracture of one Skull-Bone from passing thro' the whole Head; but there is more reason to believe that they have the three following Uses, that is to say, 1. To promote the transpiration of the Brain. 2. To give Passage to the Vessels that go to the Diploe. 3. To retain the Meninges, and to support the Mass of the Brain, which is cover'd by them.
What are the Names of the Bones that compose the Skull?
The Bone of the fore-part of the Head is call'd Sinciput, or the Fore-head-Bone, as also the Frontal or Coronal Bone. The Bone of the hinder-part, enclos'd within the Lambdoidal Suture, is term'd the Occipital. The two Bones that form the upper-part, and are distinguish'd by the Sagittal Suture, bear the Name of Parietals, one being on the Right side, and the other on the Left. And those behind the Ears are call'd Temporal, Squamosa, or Petrosa. These also are distinguish'd into the Right and Left Temporals, and are join'd to the bottom of the Parietal by a bastard squamous Suture.
What is most remarkable in the thickness of the Skull-Bones?
The Diploe, which is nothing else but a Plexus or Contexture of small Vessels, that nourish the Bones, and in the middle of their thickness make the distinction of the first and second Tablature of the Bones; whence it sometimes
happens that an exfoliative Trepan, or Semi-Trepan, is sufficient, when the first of these two Tables is only broken, the other remaining entire.