Royal Army Medical Corps training pamphlet no. 3 / War Office.

Date:
1944
Catalogue details

Licence: Public Domain Mark

Credit: Royal Army Medical Corps training pamphlet no. 3 / War Office. Source: Wellcome Collection.

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    collar-bone and shoulder-blade which attach the arm to the chest wall; and (3) the bones of the lower limb, including the hip-bone which attaches the leg to the spine. THE AXIAL SKELETON 21. The skull consists of a brain-case (the cranium), formed from 8 bones, and the face, formed from 14. After infancy, 21 of these 22 bones are so closely joined that the skull seems to be a single bone. The one exception is the lower jaw or mandible, which is attached by a nee joint on each. side of the cranium in front of the ear (Fig. 9). The cranium forms a stout bony case to hold the brain. The upper portion (covered by the scalp) is called the vault. The lower portion, concealed beneath the muscles of the neck, is known as the base. The base is less elastic than the vault, and in places thinner. It is the part most often broken in falls on the head—“ a fractured base.”’ Besides a number of small holes to permit passage of nerves and arteries, the base contains a large opening through which the spinal cord, the main nerve trunk of the body, passes down into the spinal canal. 22. The spinal column consists of 33 vertebrae; but as nine of these are fused to form the sacrum and the coccyx, there are only 26 separate bones. As Fig. 9 shows, it is divided into the following regions :— The neck—cervical vertebre .. kK “ 7 The back—dorsal or thoracic vertebiae he ch te The loins—lumbar vertebre .. his eis 5 The rump or sacrum—sacral vertebra. ste Shen ae _ The coccyx—coccygeal vertebre sie mi 4 The vertebre differ from one another a good deal in size and shape: those at the top of the spinal column, which form the neck, are thin and light, while those lower down, which form the back and loins, are thick and heavy. Together they form a jointed elastic pillar which supports the trunk and skull. Each vertebra has three principal parts (Fig. 9). A’ strong mass of bone in front is known as the body ; a bony arch at the back forms the spinal canal; and, thirdly, attached to this bony arch are various bony prajections or processes which lock the separate vertebre together and give attachment to the ribs and the muscles of the back. The sacrum is a single wedge-shaped bone consisting of« 5 vertebre fused together. The coccyx, situated below the | sacrum, consists of a number of rudimentary vertebre (generally four). The sacrum and coccyx together form the back of the pelvic cavity (Figs. 9 and 11).