ARTICULATIONS OF THE POSTEBIOB LIMBS. 165 



with the duty of transmitting to the leg the action of the muscles which are 

 attached to the patella. They are distinguished according to their position, 

 as external, internal, and middle. (Fig. 92, 2, 3, 4.) 



a. The external patellar ligament, the largest and most powerful, is a 

 flattened band, attached, by its lower extremity, to the culminating point of 

 the anterior tuberosity of the tibia. Its upper extremity is fixed to the 

 anterior face of the patella, and is confounded with the patellar insertion of 

 the long vastus muscle. It is joined to the internal ligament by a very 

 resisting aponeurotic expansion, a dependency of the fascia lata. 



b. The internal patellar ligament also forms a flattened band, longer, but 

 not so wide or thick as the preceding. Its inferior extremity is attached to 

 the inner side of the anterior tuberosity of the tibia. Its superior extremity 

 becomes much thickened and fibro-cartilaginous, and is inserted into a 

 prominence inside the patella. This fibro-cartilaginous portion (Fig. 92, 3') 

 of the ligament glides on the internal border of the femoral trochlea, and 

 may justly be considered as a complementary apparatus of the patellar 

 surface. The ligament, joined to the preceding by the fibrous fascia already 

 mentioned, is mixed up, inwardly, with the aponeurosis of the adductor 

 muscles of the leg. 



c. The middle patellar ligament is a round cord, situated, as its name 

 indicates, between the other two, concealed beneath the aponeurosis which 

 unites these, and in the middle of the adipose tissue protecting the synovial 

 capsules in front. It leaves the anterior face of the patella, and descends 

 vertically to the tibia, to be lodged in the fossa in the middle of the anterior 

 tuberosity, where a small synovial bursa facilitates its movements. 

 Its inferior extremity is inserted into the most declivitous part of this 

 excavation. 



B. Ligaments wJdcli attach the thigh and leg bones. — These are six in 

 number : 1 , A femoro-patellar capsule maintaining the patella against the 

 femoral trochlea ; 2, Five femoro-tibial ligaments, as follows : two lateral, 

 iW»«xternal and internal ; a posterior ; and two interarticular, distinguished 

 with reference to their inferior insertion into anterior and posterior. 



a. The femoro-patellar capsule is a membranous expansion which covers, 

 above and laterally, the superior synovial membrane. This capsule is 

 attached by its borders around the femoral trochlea and the periphery of the 

 patellar surface. It is extremely thin in its superior part ; but laterally it 

 is thicker, and constitutes two wide fibrous fasciculi which bind the patella 

 to the eccentric sides of the two condyles, and is described in several works 

 as two special ligaments. Its external face is covered by the insertion of 

 the long vastus and the crural triceps. 



b. The lateral ligaments are two ribbon-shaped cords situated at the 

 extremities of the transversal axis of the articulation, more behind than 

 before ; they are relaxed during flexion, and very tense in extension. 



The external, the shortest and strongest, proceeds from one of the hollow 

 facets on the external condyle of the femur, and is inserted into the head of 

 the fibula by its inferior extremity, after gliding over the external tuberosity 

 of the tibia by means of a special synovial bursa. It is covered by the 

 crural or tibial aponeurosis, and covers the tendon of the popliteus, from 

 which it is sometimes separated by a vesicular synovial membrane. 



The internal is attached, superiorly, to the eminence of insertion that 



surmounts the eccentric face of the internal condyle, and descends vertically 



to the tibia, gliding over the margin of its articular surface by means of a 



small facet covered with cartilage, and a cul-de-sac prolongation of the 



14 



