| A | B |
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| in terms of structure there are two types of joints | 1. joints in which the articular surfaces of the bones are united by fibrous tissue or cartilage (fibrous or cartilaginous joints). 2. joints in which the articular surfaces are not attached to each other but are held in contact by a sleeve of fibrous tissue supported by ligaments (synovial joints) |
| fibrous joints | often called syndesmosis joints. degree of movemnt determined by the amount of fibrous tissue between the articular surfaces. in general, the smaller teh amount of fibrous tissue the more limited the movement. 2 types of fibrous joints; 1. membraneous (i.e. interosseus membrane) 2. sutural (i.e. sutures of skull) |
| 2 types cartilagenous joints | 1. synchondroses (united by hyaline cartilage) e.g. epiphyseal plate. 2. symphyses (united by hyaline and fibrocartilage) e.g pubic symphysis |
| synovial joints | approx 80% of joints in adult skeleton. have much greater range of movement than other types of joints. nearly all joints in upper and lower limbs are these. the articular surfaces are not attached. each articular surface is covered by hyaline cartilage |
| movement in synovial joints | type of movement depends on the type of the joint and shape of articular surfaces. 6 degrees of freedom. the 6 DOF are: 3 linear directions (along each axis) and 3 rotations (about each axes). not all synovial joints have all 6 DOF. in multi-joint movements the DOF in the segmental chain is the sum of the DOF in all joints |
| joint stability | refers to the strength of the bond between the bones. stronger the bond the more stable the joint |
| joint flexibility | refers to the degree of movement in the joint. in general the greater the stability of the joint the lower the flexibility of the joint |
| condyloid joint | allows movement in two directions |
| saddle joint | allow flex/ext, ab/adduction and circumduction |
| rotation joint | only movement allowed is rotation about the longitudinal axis of the bone |
| hinge joint | only two movements allowed are flex/ext |
| gliding joint | allow short gliding movements in many directions not around any specific axis |
