Broca's angle is that included between the auricular foramen, the subnasal point and the ophryon.
Camper's angle is that included between the auricular foramen, the point of insertion of the upper incisors and the metopic point.
We, on the contrary, in judging of the facial angle, or rather of the existence and degree of prognathism, have resorted to inspection, aided by certain facial lines, namely (Fig. 104):
a. Vertical Facial Line.—If the subject holds his head level, with the occipital point in contact with a vertical rod, and his gaze fixed straight before him, then what we call the vertical line is the line perpendicular to the horizontal direction of the gaze, and tangent to the extreme anterior limit of the brain. This line, in the perfect human face, is perpendicular to the horizontal line uniting the auricular point with the subnasal point, and hence forms a right angle with it.
b. Line of Facial Profile.—This is the line uniting the nasal point with the subnasal point. This line is never vertical, and therefore cannot form a right angle with the auriculo-subnasal line, but forms an angle that approximates more or less nearly to a right angle (85°): this is the facial angle.
Transversely there is only one line for us to consider, and it has already been noted:
c. The auriculo-subnasal line, or line of orientation.
Facial Norm.—Our attention should be directed, as we have already said:
1. To the forehead.