Artistic Anatomy of Animals

by Édouard Cuyer

Fig. 57.—Skull of the Horse: Measure of the Facial Angle by the Method of Camper.[18] Angle BAC = 13°.

The internal wall of the cranial cavity is shown by the dotted line.

[18] We have indicated on this sketch of the skull of the horse the facial angle measured by the method of Camper, in order that the correspondence with [Fig. 56] may be more complete. But it is certain that the procedure here employed is in practice not satisfactory, since the apex of the angle, as we can demonstrate, is found to be situated within the contour of the head, and that, consequently, it is rather difficult to localize it precisely in the case of a given skeleton. Further, because of the absence of the base of the nose in the complete skull, the auriculo-nasal line cannot be accurately fixed. It would be the same for most other animals. This is why the method employed for these latter is preferably that of Cuvier, or, again, that of Cloquet. In the former, the apex of the angle of Camper is transferred to the free border of the upper incisors, but these teeth may be absent, and, on the other hand, ruminants are destitute of them. In the second, the same apex is placed at the alveolar border, and the angle then becomes fairly easy to appreciate.

Besides, in animals the cranium is very prominent superiorly, and the face, more or less elongated, is sharply projected downwards and forwards; in man the cranial region occupies not only the superior, but also the posterior part; the face is short and of a compact form. The human head, in its general aspect, may be compared to a sphere, while the skull of the quadrupeds presents the aspect of a quadrangular pyramid, with the base turned upwards and the summit at the incisor teeth.

Direction of the Head.—Before entering on the study of the bones of the head, it is necessary, in our opinion, to agree as to the position in which we shall suppose it to be placed.

The question may seem to be one of little importance; nevertheless, it cannot be regarded as indifferent, since authors are not all agreed on this subject.

Some suppose it to be placed vertically—that is, with the incisor teeth turned directly downwards. Others, on the contrary, suppose it to be placed horizontally, resting on the whole length of the lower jaw, the face being then turned upwards. These two extreme methods of arrangement appear to us to possess inconveniences—at least, for comparison with the human head.

Indeed, if, when the head is vertical, the same regions of the face (forehead, nose) are, in the case of animals as well as man, turned forward, the lower jaw ceases to merit its appellation, as it is then situated, not below, but behind the upper. Furthermore, if this position is chosen, for example, for modelling or drawing, it cannot be obtained without difficulty when we have to deal with an isolated piece of the skeleton, on account of the absence of equilibrium, which it is necessary to obviate. It is true that the question of convenience should not take precedence of all others, and it suffices for us in this connection to recall, in regard to the human pelvis, that, although the older anatomists used to represent it as resting commodiously on the three angles which terminate it at its lower part (ischial tuberosities and coccyx), this attitude being false, it is customary now to incline the superior aspect forwards, inasmuch as this arrangement more nearly conforms to reality, in spite of the fact that it is a little more difficult so to dispose an isolated pelvis. Further, to return to the head; if its vertical direction can be demonstrated, for example, in many horses, it is not sufficiently general to be adopted as the classic position.

In regard to the facility of placing in position, the horizontal direction is certainly to be preferred; but this is also far removed from the natural position in the animal while in the state of repose. On the other hand, the mind is not satisfied with the idea that certain regions of the face, such as the nose and the forehead, are then directed upwards. And yet it is necessary to come to a decision, seeing that what we are now investigating applies also to the position to which it is necessary to give the preference in placing the skeleton of the head when we wish to draw it in profile. That which we adopt is a compromise, but to us it seems more rational.

The position of the head of the horse, to be normal, should be such as to give it an inclination of 45°. In this case the lower jaw is still posterior; and, for this reason, we see in adopting this position some inconveniences from a didactic point of view. Accordingly, we will suppose the head brought a little nearer to the horizontal, and this, from the imaginative point of view, has certainly an advantage which we cannot afford to neglect when addressing artists.