116 ARTICULATIONS OR JOINTS 



the atlas and axis when the odontoid process of the 

 axis serves as a pivot around which the atlas turns. 



The Apposition of Joint Surfaces. This is accom- 

 plished by (1) atmospheric pressure as in the hip- 

 joint; (2) synovial fluid; (3) ligaments to a small 

 extent; (4) muscles to the greatest extent. A short 

 muscle may act on more than one joint the gluteus 

 maximus extends the hip and also the knee through 

 its insertion into the fascia lata. 



NOTE. The various articulations of the body have 

 not been described, as they are beyond the scope of 

 this book. However, a general understanding of their 

 attachment, position, and the bones they hold together 

 can be obtained from the plates. 



QUESTIONS 



1. Name the structures which enter into the formation of a 

 joint. 



2. What are the functions of ligaments? 



3. Describe a synovial membrane. 



4. Give the varieties of synovial membranes. 



5. Do joints contain a fluid? What is its function? Name? 



6. Where are the varieties of synovial membranes located 

 usually? 



7. Give the classification of joints included under the three 

 main groups. 



8. Give examples of an immovable joint or synarthrosis. Mixed 

 joint or amphiarthrosis. Movable joint or diarthrosis. (See Table 

 of Articulations.) 



9. What movements are admitted in joints generally? 



10. What do you understand by flexion? Extension? Abduction? 

 Adduction? When occurring in the movements of a joint? 



11. By what means are joint surfaces held in apposition? 



12. What do you understand by the terms: Gliding movement? 

 Angular movement? Circumduction? Rotation? 



