528 A MANUAL OF ANATOMY 



branch, which goes with the medullary artery into the interior of the 

 fibula ; (2) periosteal branches to the fibular periosteum ; and (3) twigs 

 to the coats of the peroneal artery. 



The calcaneo-plantar branch arises from the posterior tibial 

 whilst it is beneath the internal annular ligament. Having pierced 

 the ligament, it divides into internal calcaneal and plantar branches. 

 The former supply the integument of the inner side of the heel, 

 and the latter are the cutaneous nerves of the inner and posterior 

 part of the sole. 



The articular branches, two or three in number, arise from the 

 posterior tibial close to its termination, and enter the ankle-joint on 

 its inner aspect by piercing the internal lateral ligament. 



The terminal branches are the internal plantar and external 

 plantar nerves, which will be afterwards described. 



THE KNEE-JOINT. 



The knee-joint belongs to the class diarthrosis, and to the sub- 

 division ginglymus. Though the chief movements are flexion and 

 extension, there is also a certain amount of gliding or to and fro 

 movement, as well as rotation. The joint, therefore, partakes of 

 the nature of an arthrodial joint. It is really made up of three 

 joints, namely, one into which the patella and the patellar surface 

 of the femur enter (femoro-patellar), and other two into each of 

 which a femoral condyle and a tibial condylar surface enter (femoro- 

 tibial). These three joints in man communicate freely with one 

 another. 



The articular surfaces are (i) the condyles and patellar surface 

 of the femur, (2) the upper three-fourths of the posterior surface 

 of the patella, and (3) the condylar articular surfaces of the 

 tibia. 



The ligaments are divided into two groups, external and 

 internal. I 



I. External Ligaments. — These are as follows : anterior or liga- j 

 mentum patellae, posterior, external lateral, internal lateral, and ; 

 capsular. ' 



The anterior ligament or ligamentum patellae is attached ; 

 superiorly to the apex and adjacent margins of the lower part of | 

 the patella, and inferiorly to the lower roygh portion of the 1 

 tubercle of the tibia, a bursa intervening between it and the ; 

 upper smooth portion of the tubercle. It is a very strong, flat, ' 

 broad ligament, the lateral margins of which are connected with | 

 the lateral patellar ligaments. 



The posterior ligament is really a part of the capsular 

 ligament. It covers the back parts of the femoral condyles, and; 

 extends between the external and internal lateral ligaments. 

 Superiorly it is attached to the upper margin of the intercondylar! 



