Human physiology Volume 1

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1850 Excerpt: ...of another, we have a case of gomphosis. It is exhibited in the union between the teeth and their sockets. Lastly, schindylesis is when the lamina of one bone is received into a groove of another; as in the articulation of the vomer, which separates the nasal fossae from each other.. The movable articulations comprise two orders:--amphiarthroses, in which the two bones are intimately united by an intermediate substance, of a soft and flexible character, as in the junction of the vertebrae with each other; and diarthroses, properly so called. The last admit of three subdivisions--enarthroses or ball and socket joints; the condyloid, in which, owing to the head being oval, the movements are not as easy in all directions as when it is spherical; and the ginglymoid or ginglymus, in which the motion can occur in only one direction, as in a hinge. The farther subdivision of the joints belongs more to anatomy than to physiology. The articular surfaces of bones never come into immediate contact. They are tipped with a firm, highly elastic substance, called cartilage; which, by its smoothness, enables the bones to move easily upon each other; and may have some influence in deadening shocks, and defending the bones, which it covers. The arrangement of cartilage varies according to the shape of the extremity of the bone. If it be spherical, the cartilage is thick at the centre, and gradually diminishes towards the circumference. In the cavity, the reverse is the case; the cartilage is thin at the centre, and becomes thicker towards the circumference; whilst on a trochlea or pulley its thickness is nearly every where alike. An admirable provision against displacement of bones at the articulations is seen in the ligaments. These, by the French anatomists, are distinguis...