PHYSIOLOGY FOR BEGINNERS 



the knee cap, or patella. The inner surface of the patella is 

 polished and covered by synovial membrane like the rest of 

 the interior of the joint ; it plays on the large articular 

 surface on the front of the femur when the knee is bent and 

 straightened. The patella lies, as it were, in the capsular 

 ligament, but is attached to the tibia by a strong band-like 

 ligament as well. To the upper edge of the patella the tendon 



of themuscle which straightens 

 the leg, the extensor muscle as 

 it is called, is attached, so that 

 by means of the patella and 

 the band-like ligament below 

 it, this muscle is attached to 



caps. - "- ">-- " fem lhfc tibia - 

 ~ \~pat 



l- 



fib - 



There are other band-like 

 ligaments at the sides and at 

 the back of the knee joint 

 which help to keep the bones 

 in place, and, with the crucial 

 ligaments, prevent the leg 

 being bent forwards at the 

 knee. 



The fibula, the smaller 

 bone of the leg, lying along- 

 side the tibia, on the outer 

 side of the leg, does not reach 

 quite as high as the knee 

 FIG. ig.-The right We joint. The outer joint, its upper end being 



half of the femur and patella sawn away. articulated with the tibia 



/em, femur; pat, patella; tit, tibia ; fib, just below. The lower ends 



fibula;, a/.s, capsule of joint; /.crucial of thg t j b j a and fibu]a f()nn 



ligaments; c, semilunar nbro-cartilages; . 



,, tendon of extensor muscle. the lnner and outer P rom '- 



nences at the ankle, and 

 are articulated with the bones of the foot. 



The Elbow Joint. The elbow joint is a hinge joint 

 between the humerus above and the ulna and radius below. 

 The lower end of the humerus is broad from side to side 

 and presents a rounded edge. This smooth edge is divided 

 into two parts by a ridge. The ulna articulates with the part 

 on the inner side of this ridge, and the radius with the part on 



