200 Diseases of Bone. 



6. 3. Imperfect Development of the Arch of the Atlas. 



— Atlas vertebra from an adult — macerated, illustrating the 

 above. 



The bone seems well developed, except that the arch is 

 incomplete on the right side, near its junction with the lateral 

 mass. G. C. 992. 



6. 4. Cervical Rib. — Eight first rib of an adult, with an extra rib 

 fused to it — macerated. 



The first rib itself has a ridge for the attachment of the 

 scalenus anticus muscle, with a groove in front and behind it. 

 The ridge separating these two grooves runs in the direction of 

 the extra rib. The extra rib has a well-marked head, neck, and 

 tubercule, with about one inch of a body, before it blends with 

 the first rib. The place of junction is much flattened, and 

 on the inner side is prolonged into a flattened spike, directed 

 forwards and inwards. G. C. 3533. 



II. CHANGES PEODUCED BY CONDITIONS AFFECTING THE 

 NUTRITION OF BONE. 



A. Changes in old age. 



6. 5. Chang-e in the Humerus from Old Ag-e. — Upper end of 

 a right humerus, in section — macerated, to show the above. 



The bone was very greasy, and was with difficulty cleaned 

 of fat and oil. The compact tissue of the shaft is diminished 

 in thickness. There is considerable atrophy of the cancellous 

 tissue at the upper end, and the whole texture of the bone is 

 lighter and more friable than in the adult condition. Tlie 

 changes in this bone may be taken as characteristic of those 

 found in the long bones of old people, when senile decay has; 

 appeared. G. C. 3334, 



Fresented by MACDO'i^A.LJ) Bkown, F.R.C.S.E. 



