Anatomy of Skeleton 



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bone. Epiphyses can be seen well in a long bone : Fig. 3 shows the condition of 

 things in the femur, where the primary centre forms the shaft of the bone, and 

 epiphyses lie on this as bony caps joined by plates of unossified cartilage to it. Such 

 a shaft is known as a diaphysis. Epiphyses can be classed as traction, pressure, or 

 atavistic : in the figure the epiphyses of the head and lower end, being in the line of 

 weight-transmission, are pressure epiphyses, while those at the muscle attachment 

 are traction epiphyses. Atavistic epiphyses are not found on the femur, and when 

 they occur they are supposed to represent some past condition or process of the bone 

 which has now no apparent function in the human skeleton. It is not impossible, 



however, that some of the other epiphyses are 

 modified earlier processes and have therefore 

 certain atavistic values. 



The epiphysial cartilage that lies between the 

 bony tissue of the epiphysis and diaphysis has 

 an important function. We have seen that the 

 shaft increases in thickness from the deposit of 

 bone under the periosteum, but it is clear that 

 this cannot lengthen the shaft, and a special 

 arrangement is necessary if growth in length is to 

 go on except by the slow process of interstitial 

 increase : such an arrangement is provided by 

 the growth in depth of the epiphysial cartilages, 

 which just keeps ahead, so to speak, of the ex- 

 tension of diaphysial ossification toward the end 

 of the bone. So the bone can grow in length as 

 long as the cartilage remains unossified, and the 

 growth ceases when the epiphysis joins the main 

 bone. It follows from this that growth goes on 

 longest at the end where the epiphysis is the last 

 to join, and such an end is termed the growing 

 end ; in all long bones except the fibula the centre 

 which forms the epiphysis at the growing end, and 

 therefore joins last, is the first to appear. 



A knowledge of the " growing ends " is 

 necessary for the surgeon who may have to 

 deal with injuries affecting them, with subsequent premature junction with the 

 shaft and, as a consequence, shortening and deformity of the bone concerned. The 

 deformity, of course, would not be so great, although present, if the injury affected 

 the epiphysis at the other end of the bone. The limb bones have their growing ends 

 at the shoulder and wrist in the arm and forearm respectively, and at the knee ends 

 of the bones in the lower limb. 



The vascular supply of bones is obtained from the arteries in the neighbourhood : 

 in long bones many small vessels enter near the ends and in the epiphyses, and their 

 tracks are seen as vascular foramina in the dried bone ; but the vessels also enter the 

 shaft, and one or two larger vessels in particular make what are termed the nutrient 

 foramina in the body of the bone. In long bones the direction of the nutrient foramen 

 is in a direction away from the " growing end " of the bone : the reason for this 

 disposition of the vessels is obscure. The larger vascular foramina are occupied by 

 veins as a rule, and nerves and lymphatics accompany the vessels into the bone. The 

 results of certain diseases and injuries of bones is explained by reference to the way in 



FIG. 3. Diagram of femur. The 

 stippled areas represent the 

 epiphyses which are formed from 

 centres of ossification distinct 

 from that of the main shaft ; 

 each of these epiphyses is 

 separated from the shaft by a 

 layer of cartilage, indicated by 

 the thick black lines, and the 

 adult consolidation of the bone 

 is brought about by the ossifica- 

 tion of these cartilaginous plates. 

 Their presence is thus a sign of 

 immaturity. 



