OSSEOUS SYSTEM. 191 



Q. How do you account for double rows of teeth? 



A. The temporary set are not removed ; the permanent 

 take another direction, usually an internal one, appearing 

 as an inner row of teeth. 



Q. Do the sesamoid bones lie in the direction of the ex- 

 tension or flexion of a joint? 



*fl. In all cases in the flexures of the joints, except in 

 the instance of the patella. 



Q. What is remarkable in the structure of these bones ? 



. Their fibro-cartilaginous, and fibro-osseous state. 



Q. Where are they most numerous and conspicuous? 



#. In the lower extremities; and they are not seen in 

 any part of the bones of the trunk. 



Q. Where are they exclusively developed? 



t#. In the fibrous organization, as in the tendons or 

 ligaments. 



Q. Do you mean to say that in their most complete 

 state of ossification, the sesamoid bones are partly fibrous? 



A. They are; for the tendinous fibres on the upper and 

 lower side of these bones so penetrate its osseous sub- 

 stance, as to be continuous. 



Q. At what age are they most numerous? 



*#. They are found in greatest number in advanced life. 



Q. In their union after fracture, how do they differ 

 from other bones? 



.#. They differ in the interposition of a kind of fibro- 

 cartilaginous substance, or, as it has been termed, ligament, 



Q. In what disease have they been seen remarkably 

 developed ? 



*#. In gout. 



