As already stated in the chapter on the cranium, the nasal bones belong to the dermal category, their special function as nose bones being a later acquisition. In their acquirement of this function they have passed through many changes, especially as the human face in its nasal features has assumed an embryonic type. In consequence, like all late embryonic acquisitions, degeneracy is apt to involve the nose.
When arrest of development of the face takes place stigmata of the nasal bones always result. Under such conditions narrowing or arrest of development of the entire nasal cavity ensues.
Deformities of the nasal septum, deflection, hypertrophy and atrophy of the turbinate bones, deformities of the maxillary sinus, hypertrophy of the mucous membrane and polypi are common. Deflection of the external nose is a very common stigma of degeneracy. Not only is the septum involved, but also the outer plates of the nasal cavity. So unstable are the bones of the face in their development that it is not an uncommon thing for the nasal process of the upper jaw on one side to be much more developed than the other. Not only is the nasal septum involved, but also the bones of the face as well, producing a fulness on the long side of the face. This stigma is very common among criminal youth. In such cases the deflected septum is due to the development of the outer plate and not vice versâ. Deflection of the septum to the left may entirely obliterate (as in Fig. [27]) the left nasal cavity. If one nostril of a rabbit be permanently closed, after the animal has attained its full growth, the nasal cavity of the affected side remains undeveloped and facial asymmetry results.
FIG. 27.
Therefore two factors are common: first, the arrest of development of the bones of the nose, and second, the clogging of the cavity, both active agents in producing a closure, resulting in mouth-breathing.
Coexisting with these is often (as in Fig. [27]) smallness of the upper jaw. In the same connection grooved teeth occur, as in the same illustration.
