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 1 The Nature, Use, and Diversity of Bone

Varieties of substance and structure

We shall reserve these differences for their own place and add those which are inferred from the substance and structure of the bones. Certain bones are completely solid, and no matter how they are broken open, no cavities or hollows are observed inside; such, among others, are the two bones of the nose [ossa nasalia] and the bone that will be numbered the second [os lacrimale] of the bones of the upper maxilla, the smallest in the area [orbita] of the eyes. Also in this category are those that are compared to the size of a sesame seed, and the two ossicles [os malleus, os incus] peculiar to the organ of hearing. All of these, unless completely dried up by the passage of time, reveal no cavity at all inside. Many appear outwardly solid, as if covered by a continuous casing or layer [osseus compactus], but when broken open some of them are seen within to be filled entirely with small pores and spaces closely resembling the cavities of extremely compact sponge [os spongiosum], or very smooth pumice, and look like dried-up mushroom, 21 as in a number of lesser bones, the bones of the carpus, and those of the tarsus; among the greater bones, the sacrum, the bodies of the vertebrae, the sternum, the heel bone [calcaneus], the talus, and the bones of the vertex. Others have, besides the small cavities placed without arrangement or number, a large and noticeably hollow pocket [cavitas medullaris], which is surrounded by very solid and strong osseous tissue [osseus compactus] in the farthest corners and marked as if with bony lines [trabeculae]. Bones that have such a cavity generally have only one. Those belonging to this class include, among the lesser bones, the metatarsal, metacarpal, and digital bones, especially the tips of the first and second digits, though it seemed otherwise to Galen, the chief of the professors of anatomy, who declared the bones of the digits solid. 22 The larger bones are equipped with this kind of cavity: the femur, tibia, humerus, lower maxilla [mandibula], the fourth bone of the upper maxilla [corpus maxillae], the frontal bone, the temporal bones, and generally the cuneiform bone [os sphenoidale]. The teeth, which are easily the hardest of all the bones, also have this type of hollow [cavitas dentis], but at the same time they are entirely without the small cavities and little pumice-like holes recently mentioned. The greater cavities [marrow] and the structure [trabecular] not unlike pumice or dried mushroom occur in bones not only to make them


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lighter for movement, 23 but also so they may contain marrow, their special nourishment, their own air, or some other special material other than marrow such as the frontal and temporal bones enclose. 24



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 1 The Nature, Use, and Diversity of Bone