78. The bones of the cranium are united by ragged edges, called sut´ures. The edges of each bone interlock with each other, producing a union, styled, in carpentry, dovetailing. They interrupt, in a measure, the vibrations produced by external blows, and also prevent fractures from extending as far as they otherwise would, in one continued bone. From infancy to the twelfth year, the sutures are imperfect; but, from that time to thirty-five or forty, they are distinctly marked; in old age, they are nearly obliterated.
Fig. 7.
Fig. 7. 1, 1, The coronal suture at the front and upper part of the skull, or cranium. 2, The sagittal suture on the top of the skull. 3, 3, The lambdoidal suture at the back part of the cranium.
79. We find as great a diversity in the form and texture of the skull-bone, as in the expression of the face. The head of the New Hollander is small; that of the African is compressed; while the Caucasian is distinguished for the beautiful oval form of the head. The Greek skulls, in texture, are close and fine, while the Swiss are softer and more open.
78. How are the bones of the skull united? What are the uses of the sutures? Mention the appearance of the sutures at different ages. What does fig. 7 represent? 79. What is said respecting the form and texture of the skull in different nations?
80. In each EAR are four very small bones. They aid in hearing.
81. In the FACE are fourteen bones, some of which serve for the attachment of powerful muscles, which are more or less called into action in masticating food; others retain in place the soft parts of the face.