[Footnote 15: Z. Oppenheimer prefers the name rachitic asthma in place of laryngismus, and suggests an explanation of the symptoms from a strictly anatomical point of view. If not correct, it is at all events interesting, as everything this ingenious writer proposes. He points to the ligament situated between the spinæ intrajugulares of the temporal and occipital bones, which, as long as it is of normal consistency, separates the jugular vein from the pneumogastric nerve. As it is covered with periosteum and dura, it is apt to ossify, and forms an osseous partition in the foramen jugulare, which participates in all the changes taking place in the periosteum. As this becomes softened and succulent, so will the ligament, either on both sides or on either. Its influence on the neighborhood depends on its size or succulence (as also on the difference in width of the foramen jugulare or lacerum, which corresponds with the difference in size of the transverse sinuses). The irritation of the pneumogastric is perhaps easily explained thereby, but in very exceptional cases only the accessory nerve would be affected. As, however, the latter controls the sterno-cleido mastoid and trapezius, and also the laryngeal muscles, and is apt to provoke cardiac paralysis during diastole, the occurrence of sudden death would be best accounted for.]
While the size of the cranium is normal, or sometimes more than normal, the face undergoes some changes which result in absolute or relative diminution of size. These depend mostly on a reduction in the volume of the jaws. Glisson knew of it, and therefore looked for the cause of rachitis in the process of dentition. Now, both maxillæ are liable to become rachitical at an early date, as early indeed as the bones of the cranium. Rachitical deposits and softening take place in them very generally. The lower maxilla is flat anteriorly, it loses its rounded outline, is shorter in longitudinal direction, while the rami are thick and clumsy; the whole bone is shorter than normal, and sometimes asymmetric. Its changed appearance is greatly due to the effect the muscles, with their powerful insertions, produce on the softened bone; mainly the masseter, also the mylohyoid, which draws the lateral portions inward, and the geniohyoid, which pulls at the central portion. Of the latter, the lower portion is drawn out, the inner and the alveolar part inward. Thus, the teeth, mainly the incisors, of the lower jaw are turned inward to such an extent that, as those of the upper look outward, the two rows of teeth do not touch but cover each other. Besides, the periosteal proliferation around the alveoli is excessive, sometimes so much so as not only to crowd the teeth into irregular positions, but even to absorb and annihilate alveolar processes in the course of the morbid changes. The cases in which the number of teeth are actually diminished by rachitis are not at all rare. In the superior maxilla the last-described anomaly is also observed. Periosteal thickening is mainly noticed about the intermaxillary bone--sometimes to such an extent that above and behind it a considerable impression takes place. The shape of the upper jaw is more spherical than normal, and the cheek-bones become very prominent.
