The Anatomy of the Joints of Man Author:Henry Morris Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: 23 CHAPTER III. THE ARTICULATIONS OF THE SKULL. There are only two pairs of movable joints connected with the skull—viz., the temporo-maxillary and the ... more »occipito-atlantal. At the former the condyles of the inferior maxilla move like hinges in the glenoid fossae of the temporal bones; at the latter the skull, as a whole, moves by means of its occipital condyles in the boat-shaped sockets of the lateral masses of the atlas. These articulations of the skull resemble one another in that each consists of two complete, symmetrical joints, placed one on either side of the median line of the base of the skulL Further, the articular surfaces of each separate joint are oblique with regard to both the vertical and the horizontal plane; thus the condyles of the lower maxilla have their long axis obliquely transverse, being directed backwards and inwards, while the inner ends of the condyles are on a slightly higher plane than the outer; those of the occiput have their long axis oblique in the antero-posterior direction, but with an inclination outwards and backwards, while their inner borders are prolonged to a lower plane than their outer. The sockets in the squamous bone and the atlas are correspondingly oblique both vertically and in their long axis in adaptation to the condyles which they respectively receive. This bilateral arrangement, or arrangement in pairs of joints, gives great width to the basis of support at the top of the spine upon which the head rests, and upon which its movements take place; it also provides a combination of strength and security with great freedom of movement, which could not possibly have been afforded by a single joint, even of much larger dimensions. These several joints share both the hinge and arthrodial characters. In each the chief, but n...« less