JOINTS CHAPTER 6 JOINTS Articulations point where two or more bones make contact Can range from simple to more complex Holds the skeleton together 3 types of joints Structural names Fibrous immovable Cartilaginous semi movable Synovial freely movable Functional names Synarthrosis fibrous Amphiarthrosis cartilaginous Diarthrosis synovial Fibrous joints Are connected by fibrous tissues ligaments have no joint cavity and are non movable 3 subdivisions are sutures syndesmoses and gomphoses Suture bones of the skull coronal sagittal lambdoidal squamous Syndesmosis plastic around bone to connect them radius ulna and tibia fibula Gomphoses peg and socket joint teeth Cartilaginous joints 2 subdivisions are synchondroses symphyses Synchondroses 2 bones are attaches by hyaline cartilage occurs at the epiphyseal plate of lone bones of children and between the costal cartilage of rib 1 and the sternum off middle line Symphysis in middle line fortified by strong fibrocartilage supportive public symphysis and intervertebral discs Synovial joints Are the encapsulated freely moving articulation these joints are fluid filled depending on their direction of movement they may be classified as either nonaxial uniaxial biaxial or multiaxial Actions of synovial joints Nonaxial carpals and tarsals are gliding and actions are not predictable uniaxial finger elbow knee and ankle pivot joints biaxial wrist knuckles and thumb multiaxial hips and shoulder actions of joints flexions angle at the joint decreases extension angle at the join increases adduction moves closes to the body abduction moves away from the body external rotations the anterior surface of the bone is moved away from the body internal rotations the anterior surface of the bone is moved towards the body planer gliding joints hands and feet non axial hinge ginglymus uniaxial permit flexion and extension elbow Finger knee and ankle pivot joint allows uniaxial rotation atlas and axis proximal radioulnar joint condyloid ellipsoidal biaxial flexions extension adduction and abduction wrist knuckles and thumb saddle joint biaxal thumb opposition ball and socket multiaxial F E A Ab E I hips and shoulders glenohumeral joint and acetabula femoral joint