. First aid in illness and injury; . of the cavities in which the process ofdigesting food occurs. The bones of the face are: two superior maxillary, the upper jawbones; two malar, the cheek bones ; two nasal, forming the foundationof the nose; two lachrymal, thin plates filling an opening in the orbit;two palate bones, attached to the rear of the superior maxillary, andcontinuing the bony roof of the mouth; two inferior turbinated bones,forming the roof to the lower chamber of the nose; one vomer, shapedlike a ploughshare, and separating the lateral halves of the nose; andone inferior maxilla
. First aid in illness and injury; . of the cavities in which the process ofdigesting food occurs. The bones of the face are: two superior maxillary, the upper jawbones; two malar, the cheek bones ; two nasal, forming the foundationof the nose; two lachrymal, thin plates filling an opening in the orbit;two palate bones, attached to the rear of the superior maxillary, andcontinuing the bony roof of the mouth; two inferior turbinated bones,forming the roof to the lower chamber of the nose; one vomer, shapedlike a ploughshare, and separating the lateral halves of the nose; andone inferior maxillary bone, the lower jaw bone. The upper and lower jaws contain the teeth, the functionof which is the reduction of food to fragments in order topermit the penetration of the digestive fluids. Every toothpresents a crown, or body projecting above the gum ; a neck,the constricted portion between the crown and the root; andthe root, or fang set into the jaw bone. Each tooth alsocontains a pulp cavity filled with tooth pulp. THE TEETH 13. The teeth are composed of four distinct structures. (1) The enamel forms the outer covering of the crown, and consists of six-sided parallel rods, about ^V of an inch in diameter. It is the densest of all animal tissues and con-tains per cent of mineral matter, which renders possible the use of the teeth in divid-ing even very hard foods. (2) The dentine, composing the greater part of the tooth, con-sists of wavy branching tubes called dental tubuli, about jJ^ of an inch in diameter and embedded in a hard substance called the inter-tubular tissue. (3) In the pulp cavity lies the pulp, a soft cellular substance, very freely supplied with blood-vessels and nerves, which enter at the tip of the root. (4) The cement, or crusta petrosa, consists of true bone and forms the covering of the root of the tooth. The teeth appear in two crops: (1) the deciduous or milk teeth, ten in each jaw, and (2) the permanent teeth, sixteen in each jaw. The four fron
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Keywords: ., bookcentury1800, bookdecade1890, bookpubli, booksubjectphysiology
