222 SKELETON. 



ference of the extremities, like that of the other long bones, pre- 

 sents a multitude of foramina for vessels and the filaments of 

 fibres to pass. It is composed in its extremities of cellular or 

 spongy structure, and in its body of compact matter, enclosing 

 a cavity occupied by cancellated structure. 



Of the Patella (Rotule.) 



The patella is a small bone, intermediate to the thigh and to 

 the leg, and placed on the fore part of the knee joint ; it is 

 smaller in proportion in females than in males. 



Its anterior face is uniformly convex and rough, and is studded 

 with a considerable number of foramina for the passage of ves- 

 sels, and for the attachment of fibres. The course of the longi- 

 tudinal fibres composing the front of the bone, is also well marked. 

 The posterior face of the patella is an extensive articular sur- 

 face, divided unequally by a broad longitudinal elevation, which 

 runs from the superior to the inferior margin of the bone. The 

 part of this surface external to the ridge, is the largest and the 

 most concave, and is applied to the trochlea, in front of the ex- 

 ternal condyle of the os femoris ; while the smaller surface is 

 on the internal side of the ridge, and is applied, to the trochlea, 

 of the internal condyle. 



The circumference of the patella is nearly oval, the long di- 

 ameter being transverse. Its thickness is much augmented 

 above, where it presents a rough, and somewhat unequal flatness 

 for the insertion of the tendon of the rectus femoris. Below, 

 the bone is thinner, and elongated into a conical point, from 

 which proceeds the tendon of the patella to be inserted into the 

 tibia. Laterally, the margins are thinner still. 



The texture of the patella is cellular, covered by a lamina of 

 condensed bony matter. It is developed in the tendon of the 

 extensors of the thigh, and with the exception of its posterior 

 face remains in a state almost entirely cartilaginous, for a year 

 or two after birth. Its base is, therefore, fibrous, in which is 

 deposited, subsequently, the calcareous matter. In its fracture 

 union is effected more frequently by the fibrous base alone, 

 than by perfect ossification. In order to put it into its proper 



