歯突起とは
以下は「Wikipedia」の解説文となる。
「The dens, also odontoid process or peg, is the most pronounced feature（明白な特徴）, and exhibits a slight constriction or neck where it joins the main body of the vertebra. The dens is a protuberance (process or projection) of the axis (second cervical vertebra). The condition, where the dens is separated from the body of the axis, is called os odontoideum（第2頚椎歯突起形成不全）, and may cause nerve and circulation compression syndrome. On its anterior surface is an oval or nearly circular facet for articulation with that on the anterior arch of the atlas. On the back of the neck, and frequently extending on to its lateral surfaces, is a shallow groove for the transverse atlantal ligament which retains the process in position. The apex is pointed, and gives attachment to the apical odontoid ligament; below the apex the process is somewhat enlarged, and presents on either side a rough impression for the attachment of the alar ligament; these ligaments connect the process to the occipital bone.
The internal structure of the odontoid process is more compact than that of the body. The odontoid peg is the ascension of the atlas fused to the ascension of the axis. The peg has an articular facet at its front and forms part of a joint with the anterior arch of the atlas. It is a non-weight bearing joint. The alar ligaments, together with the apical ligaments, are attached from the sloping upper edge of the odontoid peg to the margins of the foramen magnum. The inner ligaments limit rotation of the head and are very strong. The weak apical ligament lies in front of the upper longitudinal bone of the cruciform ligament, and joins the apex of the deltoid peg to the anterior margin of the foramen magnum. It is the fibrous remnant of the notochord.」
【参考になるサイト】
・イラストや写真を掲載しているサイト-Ⅰ
・イラストや写真を掲載しているサイト-Ⅱ
・イラストや写真を掲載しているサイト-Ⅲ
・イラストや写真を掲載しているサイト-Ⅳ
・イラストや写真を掲載しているサイト-Ⅴ
・イラストや写真を掲載しているサイト-Ⅵ
・イラストや写真を掲載しているサイト-Ⅶ
