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Monday , 18tf/i January 1858. 
The Right Rev. BISHOP TERROT, V.P., in the Chair. 
The following Communications were read — 
1. On the Mechanism of the Knee Joint. By Professor 
Goodsir. 
After alluding to the comparatively superficial manner in which 
physiologists, with the exception of the brothers Weber, have hither- 
to investigated the structure and movements of the joints, the author 
gave an abstract of the general results which he had formerly obtained 
in an examination of the knee-joint, made with reference to Meyer’s 
valuable observations. He had found that, as stated by Meyer, 
the thigh and leg rotate on one another in opposite directions, — at the 
close of extension, and at the commencement of flexion ; and that 
the co-ordinated movements in the patella, the ligaments, and mus- 
cles correspond generally with the account given by that observer ; 
but in addition he had ascertained what had previously escaped notice, 
1. That the articular surfaces of the femur, tibia, and patella are 
not continuous but faceted surfaces. 
2. That in consequence of this faceted configuration, and the 
peculiar manner in which the opposite articular surfaces move on one 
another, they are in no position of the joint congruent throughout, 
but gape more or less in different parts of their extent. 
3. That in addition to their lubricating function, the so-called 
Haversian glands, or fatty folds of the synovial membrane, are ar- 
ranged with reference to the resulting gaps or chinks between the 
opposite articular surfaces,, each gap, as it opens out, being simul- 
taneously occupied by the fatty synovial pad provided for it, and 
which is forced or dragged into the chink, and pulled or forced out 
again by special arrangements. 
The author next proceeded to state, as introductory to the me- 
chanism of the knee -joint, the results which he had latterly obtained 
in his examination of other diarthrodial articulations. 
1. All diarthrodial surfaces are faceted, and consist of areas of 
distinct configuration and movement. 
2. These facets and areas are marginal or terminal, and central 
or acting — the former giving steadiness to the action of the joint, 
aud supplying surface on which it rests securely at the opposite ex- 
