大臼歯 - Dens molaris

説明

The Molar Teeth (dentes molares) are the largest of the permanent set, and their broad crowns are adapted for grinding and pounding the food. They are twelve in number; six in each arch, three being placed posterior to each of the second premolars.

The crown of each is nearly cubical in form, convex on its buccal and lingual surfaces, flattened on its surfaces of contact; it is surmounted by four or five tubercles, or cusps, separated from each other by a crucial depression; hence the molars are sometimes termedmulticuspids. The neck is distinct, large, and rounded.

Upper Molars.—As a rule the first is the largest, and the third the smallest of the upper molars. The crown of the first has usually four tubercles; that of the second, three or four; that of the third, three. Each upper molar has three roots, and of these two are buccal and nearly parallel to one another; the third is lingual and diverges from the others as it runs upward. The roots of the third molar (dens serotinus or wisdom-tooth) are more or less fused together.

Lower Molars.—The lower molars are larger than the upper. On the crown of the first there are usually five tubercles; on those of the second and third, four or five. Each lower molar has two roots, an anterior, nearly vertical, and a posterior, directed obliquely backward; both roots are grooved longitudinally, indicating a tendency to division. The two roots of the third molar (dens serotinus or wisdom tooth) are more or less united


This definition incorporates text from a public domain edition of Gray's Anatomy (20th U.S. edition of Gray's Anatomy of the Human Body, published in 1918 – from http://www.bartleby.com/107/).

画像

e-Anatomyをダウンロードする

携帯あるいはタブレットのユーザーは e-Anatomy をアップルストア、あるいはグーグルプレイでダウンロードすることができます。

アップルストアではe-Anatomy グーグルプレイではe-Anatomy