Agricultural zoology / with an introduction by E.A. Ormerod, trans. by J.R.A. Davis.

  • Bos, Jan Ritzema.
Date:
1894
Catalogue details

Licence: Public Domain Mark

Credit: Agricultural zoology / with an introduction by E.A. Ormerod, trans. by J.R.A. Davis. Source: Wellcome Collection.

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    but, in man, the last-named are followed by five vertebrae immovably united together to make up the sacrum, and these again by tail- or caudal vertebrce. Man has four such vertebrae, all poorly developed, and fused with one another (Fig. 2, 5); but in many animals there are a large number, movably united to make up a tail. The ribs, which in mammals bound the chest, are jointed to the thoracic vertebrae. Man has 12 pairs of ribs; each rib consists of a bony part behind and a gristly (cartilaginous) part in front. The so- called true ribs (Fig. 2, 14) [the upper pairs] are movably united with the breast-bone, but this is not the case with the false ribs (Fig. 2, 15). In the head we distinguish the brain-case or cranium, and the skeleton of the face. The first contains the cranial cavity in which the brain is enclosed. We distinguish—2 frontal bones (fused to- gether in man, Fig. 2, 6); 2 parietal bones (7); 2 temporal bones (8) ; an occipital bone (9) composed of several pieces fused together, perforated by the foramen magnum [where brain and spinal cord unite], and bearing two elevations or condyles [for effecting union with the backbone]; and the sphenoid and ethmoid bones which make up the base of the cranium. The facial skeleton consists of the framework of the jaws and palate, and, together with some of the cranial bones, bounds the cavities in which the eyes are contained (orbits), and the nasal cavities. It consists of the maxillary bones (Fig. 2,12), the pre- maxillary bones (Fig. 3, 7,—in man these 4 bones are fused together into one piece), the nasal bones, the lachrymal bones, the ploughshare bone (vomer), the turbinated bones, the cheek-bones (or malars. Fig. 2, 11), the palate-bones, and the lower jaw (Fig. 2,13). (The last originally consists of two symmetrical halves.) The upper and lower limbs are built on the same type, and therefore consist of corresponding parts
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