beyond the centre of gravity, the shoulders are consequently more rounded, the strain on the muscles of the back considerably increased, and if this influence were suffered to continue, a permanent deformity would be the necessary result.
Nor is deformity of the spine the only consequence of this forward tendency of the head, when unsupported by the due action of the muscles of the back. As will be seen by an examination of the models in our museum, which have been constructed for the express purpose of illustrating this important point, when the head falls forward the spine becomes bent, the intervertebral cartilages thinned on the inner portion of the vertebral column by the pressure, and the ribs are forced into a totally different position than that ordained by nature. Instead of standing out at a considerable angle from the spine, and thus affording free scope for the action of the heart and lungs, which are the organs essential to existence, the chest falls downwards, pressing on the abdominal cavity, the ends of the ribs are brought into closer approximation, the sternum or chest-bone is forced inwards, and the cavity of the chest considerably diminished. In addition to this, the contents of the abdomen are prevented from acting properly, as the space is encroached upon by the organs of the
