358 Anatomy Applied to Medicine and Smgery. 



than when it is extended, or when, even extremely flexed, 

 or the flexion may be due to the tendency to put the least 

 possible tension on the ligaments, since, when semi-flexed, 

 these, with the exception of the ligamentum patellae and 

 the anterior part of the capsule, are all relaxed. The 

 cause of the flexion, however, may be the reflex irritation 

 of the nerves supplying the muscles that control the joint, 

 since these muscles are governed by the same nerves that 

 supply the articulation, and hence, when they are reflexly 

 contracted, flexion results, since the hamstring are more 

 powerful than the extensor muscles. When heat, or 

 cold, or blisters, etc., is applied to the knee joint, 

 the beneficial effect that generally follows, may be 

 due to reflex stimulaton of the nerves i.e., the 

 plexus patellae, or, it may be dependent on dilita- 

 tion of the superficial bloodvessels of this region, and, since 

 these superficial arteries are branches of the deep arteries 

 that supply the interior of the articulation, it follows that 

 dilitation of the former will, to some extent, at least, with- 

 draw the blood from the latter, i.e., will lessen the conges- 

 tion of the interior of the joint. 



Movable Bodies in the joint may be portions of 

 cartilage, or remnants of embryonic tissue which have, 

 later on, developed so as to produce tags projecting into 

 the interior of the articulation, or they may be synovial 

 processes, the result of chronic inflammation of the serous 

 membrane, or, lastly, detached nodules in cases of rheum- 

 atoid arthritis. These movable bodies may slip between 

 the contiguous bones and cause a sudden, extreme pain, 

 with fixity of the limb, due to a reflex spasm of the mus- 

 cles. When the leg is flexed and the biceps strongly con- 

 tracted, as in the act of kneeling, the inner tuberosity is 

 slightly separated from the femur, and this position favors 



