Читать книгу Mother, Nurse and Infant - S. P. Sackett - Страница 19

Fig. 5.

The os coccygis.

The OS COCCYGIS (Fig. 5) is three or four little bones united together on the median line of the body, and attached to the os sacrum. Each little bone is tipped with cartilage, and they are so united as to be movable. The entire bones form a pyramid, the apex of which is below. The internal surface is smooth, like that of the sacrum, terminating the plane of the sacrum and bounding it anteriorly.

Fig. 6. Vertical section of the pelvis.

Fig. 6—Inlet, outlet, and axis of the pelvis. a, b, plan of inlet—superior strait; c, d, plan of outlet, or inferior strait; e, f, axis of cavity; g, the coccyx extended as it is in labor.

Of the JOINTS OF THE PELVIS it is only necessary here to say that there is no motion in them to facilitate labor, except that the sacro-coccygeal joint is of the kind called ginglymoid, admitting of extensive motion, especially backward, so as to permit the enlargement of the lower outlet an inch or more. (Fig. 6.)