Book One -- The things that sustain and support the entire body, and what braces and attaches them all. [the bones and the ligaments that interconnect them] | Chapter 6 On the Eight Bones of the Head and the Sutures Connecting Them

Appendix B: On the occurrence of cohesive squamous joints instead of sutures (1555 edition, pp. 33-34)

But at the same time three sutures, most particularly the coronal, produce for me the likeness not so much of a suture as of a harmonia [sutura plana]. 133 Of the cohesive squamous joints with which this account is concerned, the part nearest to the coronal suture (from H to A in figures 3, 4) [s. sphenoparietalis], to the vertex (I 134 in figure 3), and to the bone that we compare to a wedge [os sphenoidale] (O in figures 3, 4) // 1555 p. 34 // must be considered a mutual attachment; likewise the most anterior region [sutura sphenofrontalis] (b under A in figures 3, 4) of the cohesive joints will be referred to the bone of the forehead [os frontale] (to L and O in figures 3, 4) and the cuneiform bone [os sphenoidale], exactly as if Nature had established them here rather than sutures because the part of the skull that is covered by the temporal muscle [pars squamosa ossis temporalis] (G in the 4th table of muscles) as by a kind of quilt or coverlet, did not need to be as thick (lest it be unnecessarily heavy), and the unfleshed 135 regions of the skull as well as its base, which had to be notably thick and irregular because of many cavities and foramina (which the accounts of the temporal and sphenoid bone will identify), so they, lest they come to harm or other damage too directly, are thick. Yet they are not entirely hard and solid, but porous (in figure 2, ai between ei and oi) between two dense plates, primarily to avoid weight. 136 Since, therefore, the entire area of the skull where these cohesive joints occur could be made thin, the sutural structure that requires larger, thicker bone surfaces would have been weak here. Besides, the bones coming up from the base [os temporale et os sphenoidale] (N, O in figure 3) are harder than those descending [os frontale et os parietale] (L, l in figure 3), and for this reason also the cohesive joints [sutura squamosa] are so fashioned that the plates of the harder bones rightly come up on the outside while those of the softer are placed inside, and are as it were covered by the more solid plates in an otherwise level surface. Because the temporal muscle is the principal cause of these cohesive joints, it shows their location [sutura parietomastoidea] (from C to G in figures 3, 4), coterminous with the lambdoid suture, which looks like a suture over the same distance as the unfleshed portion of the skull extends and the bones themselves are thick. Indeed, at the anterior end of the cohesive joints [sutura sphenofrontalis] (from b towards g in figures 3, 4) we see a type of suture where the bones constituting the upper maxilla [os zygomaticum, sutura frontozygomatica] (Q, Q to L in figures 3, 4) turn out thick like the bones of the head, so that over their entire course these cohesive joints are not altogether squamous.



Book One -- The things that sustain and support the entire body, and what braces and attaches them all. [the bones and the ligaments that interconnect them] | Chapter 6 On the Eight Bones of the Head and the Sutures Connecting Them