158 COUES ON THE OSTEOLOGY 



would seem to preside especially over the outward rotation ; besides which various 

 flexors, extensors, glutei, etc., are made to act either as external or internal rotators b V 

 some peculiarity in their insertion into the femur. 



In the positions and movements of the femur we see its perfect adaptation to the 

 functions it has to perform, — those of affording a short, stout point d'appui for the leg at 

 a sufficient distance from the body, and of powerfully impressing upon the distal segments 

 of the lower extremity anteroposterior and rotatory motions; this force of motion decreas- 

 ing as we proceed from the body just in proportion as extent of motion is augmented It 

 would not seem that the length of the first segment of a limb is an indication of the 

 powers of that extremity. Thus among the CfauUdm and the TrocMMce, whose powers 

 of flight are unsurpassed, the humerus is very short ; but in them, as in the case before us 

 of the Loon's femur, the primary segment is most powerfully acted upon by laro- e muscles 

 which force of motion is by a common law of mechanics converted by the Ion- distal 

 segments into extent and rapidity of motion. ° 



The distal extremity of the femur is no less interesting than the proximal The shape 

 of the two condyles, as well as of the articulating surfaces themselves, is very different 

 The external condyle is very much the larger of the two, projecting more outwards and 

 as much further downwards than the internal one, as from the obliquity of the femur it is 

 necessary to bring the faces of the two upon the same plane. 1 Its articulating surface is 

 longitudinally very convex, transversely equally concave, by a rounded sulcus which 

 causes its convexity to present a ridge on each side. This is the true articular surface of 

 the outer condyle, and it is closely coaptated with the head of the fibula Upon the 

 internal side of the condyle there is also, however, a facet of an oval shape, which articu- 

 lates with a corresponding facet on the fibular edge of the head of the tibia. The proper 

 femoro-tibial articulation is however with the internal condyle. The latter is much less 

 irregular than the outer one, having simply an oval extremity, convex in both its axes 

 which rests upon the very slightly depressed, broad, flat head of the tibia. The movements 

 of the knee-joint will be spoken of after noticing the bones of the leg. 



Tibia, This bone is very long, measuring with its spine seven ami a half inches and 

 consequently containing the length of the femur nearly four times. Its spine is j us i two 

 inches long, leaving a length of five and a half inches for the tibia proper Below it is 

 flattened antero-posteriorly, indicating its further expansion into the two condyles 

 ("malleoli"). More superiorly, it becomes sub-quadrilateral. The outer posterior eclo-e 

 forms for nearly its whole extent the fibular anchylosis. The inner anterior edge is the 

 most prominent, About one and a half inches below the head of the bone it rises as a 

 very prominent thin crest, with a sharp margin. This crest curls over forwards more and 

 more until it has on its anterior aspect a deep longitudinal concavity, and, preserving much 

 this shape, is prolonged two inches above the head of the bone as an exceedingly prominent 

 spine. The posterior aspect of this spine is at its base prolonged directly from the articular 

 head oi the bone, forming a deeply concave continuation of the joint, exactly resembling 

 the olecranon of the human species. 2 Indeed, this articulating' surface of the tibia hat 

 almost exactly the shape and general appearance of the sigmoid cavity of our ulna. The 



1 Prof. Owen considers our olecranon to be not a patella same principle as in man h,,t tl,„ , »,* ■ n 



2 ti • r«- • , , , ducted, the outer condyle instead of the inner must be the 

 2 Tins difference in the length of the two condyles, to atone longest. ' inner most De tHe 



for the obliquity of the shaft of the femur, is precisely upon the 



