. Bensley's Practical anatomy of the rabbit : an elementary laboratory text-book in mammalian anatomy. Rabbits -- Anatomy. rrw. Fig. 24. Outline sketch of the proximal end of the femur of a young animal: cf., principal epi- physis for the head of the femur. The accessory epiphyses are for the great (), lesser (), and third () trochanters. blasts lying directly in the perichondrium, or later the periosteum, a process of formation of intramem- branous bone goes on, continuing to the end of the period of growth, and the result of this peripheral deposition of bone lamellae is, th
. Bensley's Practical anatomy of the rabbit : an elementary laboratory text-book in mammalian anatomy. Rabbits -- Anatomy. rrw. Fig. 24. Outline sketch of the proximal end of the femur of a young animal: cf., principal epi- physis for the head of the femur. The accessory epiphyses are for the great (), lesser (), and third () trochanters. blasts lying directly in the perichondrium, or later the periosteum, a process of formation of intramem- branous bone goes on, continuing to the end of the period of growth, and the result of this peripheral deposition of bone lamellae is, that the trans- verse diameter of the bone is greatly increased. The enlargement of the marrow-cavity, with which this is associated, is produced by the ab- sorption of bone from the interior. In young animals both the epi- physial centres and the masses of cartilage in which they are formed are sharply marked off from the body of the bone (cf. Fig. 26). This is largely because the formation of the epiphysial centres tends to lag behind that of the main centres, and thus the cartilage extremities of the bones are evident long after the formation of the shaft is under way. In the epiphysial centres the bone formation is endochondral. The bone masses which they form are distinguished as epiphyses. During the period of growth they are connected with the body of the bone by plates of epiphysial cartilage, into which the surrounding perichondrium ex- tends as an ossification ridge. In this region bone formation takes place, with the result that the whole structure is greatly increased in length. After the period of growth, the duration of which differs in different bones, the epiphyses become firmly co-ossified with the body of the bone, although the lines of junction or epiphysial lines may still be visible. Thus in theMistal extremities of the radius and ulna, in the proximal extremities of the fibula, or in the bodies of the lumbar vertebrae, the epiphysial lines appear even in old
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