598 THE CURVATURES OF THE ARTICULAR SURFACES, ETC. 



XXXVI. ON THE CUEVATUEES OF THE AETI- 

 CULAE SUEFACES, AND ON THE GENEEAL 

 MECHANISM OF THE HUMAN HIP-JOINT* 



IN consequence of the vague and unsatisfactory manner in 

 which anatomists and physiologists have until lately exam- 

 ined the mechanism of the joints, it appears to have been 

 assumed as self-evident that the cartilaginous surfaces of the 

 head of the thigh-bone and of its socket must be spherical. 

 If, however, the outlines of the transverse and antero-posterior 

 curvatures of the head of the femur be attentively followed 

 by the eye against the light, it will be at once observed that 

 they are not arcs of circles. The transverse curves as seen from 

 the front or back of the bone are two in number, one above, 

 the other below the fossa for the ligamentum teres, and they 

 increase in rapidity as they approach that fossa. 



The transverse curves are also two in number, and may be 

 observed by looking at the outline of the head of the bone 

 from the inner side, holding it so that the ridge extending 

 from it to the lesser trochanter may be perpendicular. If the 

 line of the ridge be then traced upwards to the outline of the 

 articular surface of the head of the bone, it will be found to 

 intersect that outline at the point of osculation of the two 

 curves of which it consists. This point is a cusp directed 

 upwards, and the two curves increase in rapidity as they 

 extend down to the front and back of the articular margiu. 

 On examining the articular surface, the eye will now be able 



* This memoir ought to have immediately followed that on the Mechanism 

 of the Knee-joint, but the manuscript from which we print was unfortunately 

 overlooked until the greater part of this volume had gone to press. EDS. 



