754 



THE POPULAR SCIENCE MONTHLY. 



Fig. 6.- 



-Diagram of Shoulder Join r, 

 to show the capsule. 



borne, and the unfortunate youth, is forced by it to leave the study 

 of medicine and turn his attention to some easier pursuit. 



Now, I think that with a little trouble one may find a way of 

 linking anatomical relationships together in a more rational way 

 than that of " Bodfi," a word which in my student days was used 



as a mnemonic to describe the form 

 of the hippocampal convolution of 

 the brain — backward, outward, down- 

 ward, forward, and inward. The word 

 also served to describe the course of 

 the ribs, but Dr. Anderson Stewart 

 has shown us how naturally the pecul- 

 iar twist the ribs take in a man arises 

 from his upright position. Taking a 

 circular steel hoop, and simply hang- 

 ing it up by one side, he shows that it 

 assumes an oval shape, like that of 

 the thorax of animals going upon four legs and whose ribs hang 

 vertically from the spine. On raising this up by one point it be- 

 comes twisted upon itself and takes precisely the peculiar bend 

 which the ribs possess in man. The advantage of a naturally 

 jointed skeleton is so obvious that I need not further discuss it 

 here, nor need I discuss the texture of bone which has been so ad- 

 mirably treated of by my friend Dr. Donald Macalister, of Cam- 

 bridge (Fig. 5). 



The ligaments and the joints were to me most puzzling until 

 Dr. Joseph Bell pointed out to me how very simple they were. 

 What is wanted in a joint is a capsule to go round 

 it so as to hold the ends of the bones together and 

 prevent the synovial fluid from oozing out. If the 

 bones have to move freely in all directions they 

 must have a ball-and-socket joint, as at the shoul- 

 der (Fig. 6) and at the hip, and there you will have 

 a simple capsule because it can not be particularly 

 strengthened at one point or another without inter- 

 fering with freedom of movement. In the case of 

 a hinge-joint, such as those of the fingers or toes, 

 elbows or knees, you will have the capsule remain- 

 ing thin at the front and back so as to leave the 

 movement free, but you will have it strengthened 

 at the sides so as to tie (Fig. 7) the bones more firmly together, 

 and the stronger parts are called lateral ligaments. If several 

 bones have to be connected, each one must be tied first of all to 

 the one nearest it, and then two or three must be tied together at 

 a time, and in this way we get the network of ligaments which 

 we find at the wrist and tarsus (Fig. 8). The same thing is true 



Fig 



— Diagram 

 of Ligaments 

 of Phalanges 

 — a capsule and 

 lateral liga- 

 ments. 



