chap. XXL] THE POPLITEAL SPACE. 429 



of the joint than when placed in front or to the outer 

 side of it. 



The Imrsse over the front of the knee. (1) The 

 patellar bursa is a large sac placed in front of the 

 patella and upper part of the patellar ligament, and 

 separates those structures from the skin. It is very 

 often found enlarged in those who kneel much, in 

 housemaids, stone-masons, religieuses, etc. The parts 

 about are well supplied with nerves, and hence much 

 pain is usually associated with acute inflammation of 

 this sac. It is in close contact with the patella, and, 

 in one case reported by Erichsen, suppuration of the 

 bursa led to caries of that bone (Figs. 45, 46, and 

 49). (2) There is a small bursa between the 

 patellar ligament and the tubercle of the tibia 

 (Fig. 46). When inflamed, it causes more pain 

 than is observed in affections of the previous bursa, 

 since it is firmly compressed between two rigid struc- 

 tures, the ligament and the bone. It is separated 

 from the synovial cavity by the pad of fat that lies 

 behind the patella. It would appear, however, to 

 sometimes communicate with the joint, since Hamilton 

 has collected three cases where incision into this 

 bursa led to suppuration of the articulation. There 

 is a pad of soft fat between the ligament and the 

 tibia! tubercle, which often protrudes a little at either 

 side of the former structure, and has been mistaken 

 for an enlarged bursa. (3) The bursa between the 

 quadriceps tendon and the femur will be considered 

 in connection with the synovial cavity. 



The popliteal space. The skin over the 

 space is not so movable as is that over the front of 

 the knee. When destroyed by injury, by burns, or 

 by extensive ulceration, the contraction of the result- 

 ing cicatrix may lead to a rigidly-bent knee. The 

 skin in this place has also been ruptured by forcible 

 extension applied to the limb in cases of contracted 



