50 



THE BOXES AND JOINTS. 



Tibio-flbula of Rcma esni- 

 lenta, twice nat. size, seen 

 from below. 



a a Grooves. 



f Foramen nutritium. 



t Anterior articular ex- 

 tremity. 



t' Posterior articular ex- 

 tremity. 



t" Groove on malleolus in- 

 ternus for tendon of 

 m. tibia/is pon/ii-nx. 



from above downwards. On the upper as also 

 on the lower surface of the bone is a groove, 

 passing from the middle towards each ex- 

 tremity; this deepens as it proceeds, and is an 

 indication of the compound nature of the bone. 

 In the middle of each surface of the bone 

 is the opening- of a canal, through which a 

 bristle may be passed : the canal has bony 

 walls. The medullary cavity is, for the most 

 part, double, being- single only in the middle. 

 The anterior extremity is articular, and presents 

 a median groove, which is prolonged on to the 

 under surface. The posterior extremity forms 

 a transverse condyle, which has at its inner 

 part a notch for the tendon of the m. tibialis 

 posticiis. 



The knee-joint consists of a capsule strength- 

 ened by the insertions of numerous tendons. 

 Within this the articular surfaces 

 of the femur and tibio-fibula are 

 connected by means of fibro-elas- 

 tic bands, which spring from the 

 latter bone and cross each other, 

 thus representing the Hg. cruciata. 

 The articular surfaces are more- 

 over deepened by loose semilunar 

 cartilages, corresponding- with 

 the inter-articular cartilages of 

 the knee-joint of man. In addi- 

 tion, on either side of the joint, 

 are found auxiliavv ligaments. 



Fig. 4 6. 



Section of the tibio- 

 tibula through the 

 under extremity. 



a Cartilaginous 

 epiphysis. 



? Marrow cavities. 



t" Connecting 

 mass. 



tfThe two cylin- 

 ders of bone. 



3. The foot (Fig. 47). 



a. The ankle, ossa tars*. The tarsus consists of two rows of 

 bones. 



a. The proximal row consists of two long tubular bones (Fig. 

 47 ac), which are parallel to each other, and undoubtedly cor- 

 respond with the astragalus (fains] and calcaneum. The bones 

 are separated in the middle, but approach each other at either end. 

 The outer of these bones (c) I have named calcaneum, following 

 Cuvier and Duges ; the inner, astragalus (a}. The two bones are 



