STUDT OF TEE JOINTS IN THE BODY. 71 



gained by the difference in the structure 

 of these two girdles? 



B. Hinge-joints. 



1 . Determine from the articulated skeleton the 



bones which form the hinge- joint at the 

 elbow. 



2. What bones form the joint at the knee? 



3. What projection at the elbow occupies a 



position corresponding to the knee-cap 

 or patella? 



4. Move the right forearm and the right leg at 



the same time; state in which direction 

 (i.e., anteriorly or posteriorly) each is 

 bent. 



5. Hold the humerus and the femur in a fixed 



position. Is lateral motion possible at 

 the knee or elbow- joint ? Show from the 

 articulated skeleton the reason for this. 



6. In how many directions can a hinge- joint 



be moved? How, therefore, can you 

 distinguish between a ball-and-socket 

 and a hinge -joint? 



7. Are the joints between metacarpals and 



phalanges ball-and-socket or hinge? 

 Why? 



8. Make a list of all the hinge- joints in the 



body, naming the bones which form the 

 joint in each case. 



C. Pivot- joints. 



i. Place the right forearm on the table with 

 the palm of the hand upward. Without 

 lifting the elbow from the table turn the 



