OSTEOMETRY; THE MEASUREMENT OF THE BONES 



139 



III. ANGLES 



1 Angle of inclination of the collum tali; the angle between the axis 

 of the neck and the sagittal axis of the bone (as in Fig. 38). 



2. Angle of torsion of the head; the angle between the longitudinal axis 



T 



FIG. 39. (After Seymour Sewell) . 



of the headjjand the plane placed tangent to the highest points of the 

 trochlea (efg in Fig. 40). 



3. Angle of inclination of the posterior articular facet; this is the angle 

 formed between the sagittal axis of the bone (i.e., the line of the trochlear 



FIG. 40. (After Seymour Sewell). 



trough) and the long axis of the posterior facet (SS, Fig. 38 with ab, 

 Fig. 39). As these two are not only in different planes, but also upon 

 opposite sides of the bone it is clear that the angle must be formed by 

 projection, which is accomplished in a practical way as follows. Steel 



