. Biology and human life. Biology. THE HUMAN ORGANISM 283 The skeleton of the head region shows many adaptations to the workings of the organism, as well as to external relations. Besides the bony protecting case of the brain we find sockets for the eyeballs and joints for the jaw. The teeth are not bones but special skin structures; there are definite sockets in the jaws, however, for all the teeth. The spaces in the face bones are very intricate and are connected with both the sensory and the respiratory functions of the nose. The whole of the hearing apparatus, together with the balancing o
. Biology and human life. Biology. THE HUMAN ORGANISM 283 The skeleton of the head region shows many adaptations to the workings of the organism, as well as to external relations. Besides the bony protecting case of the brain we find sockets for the eyeballs and joints for the jaw. The teeth are not bones but special skin structures; there are definite sockets in the jaws, however, for all the teeth. The spaces in the face bones are very intricate and are connected with both the sensory and the respiratory functions of the nose. The whole of the hearing apparatus, together with the balancing organ, is inclosed by the bone of the skull (see page 232). There are many openings in the base of the brain box, through which nerves and blood vessels pass. In a saddle-shaped depres- sion in the base of the skull, back of the eyes, lies a two-lobed organ, the pi- tuitary gland, which pro- duces important internal secretions (see Fig. 124 and page 178). 226. The structure and growth of bones. The skeleton of vertebrates differs from the exoskeletons of invertebrates in one very important respect: it is made up of living tissue. Bone cells absorb from the lymph a large proportion of mineral matter and deposit this as lime salts outside of themselves (Fig. 137). In the development of the individual from the one-celled stage there appear groups of. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Gruenberg, Benjamin C. (Benjamin Charles), 1875-1965. Boston, New York [etc. ] Ginn and Company
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