Types of Synovial Joints

Types of synovial joints ● ● ● The table lists them from most stable to least stable All moveable joints (not plane and pivot) = flexion and extension Classified as uniaxial, biaxial or multiaxial depending on the planes that they can move in Type of synovial joint Plane Description - Slide or glide over one another Uniaxial Location - - Pivot Hinge - - Circular articular surface that can move around a stabilised axis - Flexion and extension Uniaxial - - - Condylar - - Saddle (thumb) - Vertebral column where they stack up on one another (accumulation = more movement) - Thoracic = anterior/posterior movement (side to side) - Lumbar = medial lateral Carpal bones in the wrist to allow small movements In the tarsals, when you take a step the foot flattens out through sliding to absorb the force Atlas rotating around the DENS of the axis (atlantoaxial joint) Creates medial/lateral rotation (shaking head no) Radioulnar joint (olecranon on the posterior surface of the elbow is where the radius is pivoting around the ulna and the ulna remains stable) In the elbow its where the radius meets the capitulum and the ulna meets the trochlea Interphalangeal joint Same for lower limbs - knee is a modified hinge joint and the interphalangeal joints Biaxial Flexion and extension (sagittal) Abduction and adduction (coronal) Round surface interacting with a flat surface The articular surfaces are incongruent (do not fit together nicely) = slightly unstable and more movement - Where the forearms meet the wrist Between the proximal and middle phalange (separating your fingers abduction) - Rounded carpals meets the flat top of the radius and ulna Articular surfaces are more congruent Flexion and extension Abduction and adduction - In the hand - first metacarpal joint The base of the metacarpal and trapezium have this joint, allowing the metacarpal to rock forward and back on the carpal Thumb - opposition - Abduction of the thumb is towards the wrist - Adduction of the thumb is back to anatomical - Ball and socket - Ball articulating with a socket shaped girdle Multiaxial Flexion and extension Abduction and adduction Medial and lateral rotations Labrum ‘lip’ - Hyaline cartilage - Deepens the joint cavity by extending the socket by a lip of hyaline cartilage to make sure the bones are tightly attached - Labrum of the shoulder is not as strong/tight as the pelvic one Pelvic girdle - Round head of the femur locks into the acetabulum CONGRUENT - Tight ligaments for stability - Helps to maintain connection between the bones at all times - There are also small, short muscles that pull the head of the femur into the acetabulum to maintain connection - Able to stand upright due to the stability of the joint Shoulder joint - Greater movement in all planes (less stable) - Ball shaped head - Scapula is where the socket is (glenoid cavity) shallow compared to the acetabulum INCONGRUENT - Lots of ligaments and muscles to pull the humerus into the socket and maintain connection (loose ligaments and fibrous capsule, rotator cuff muscles do most of the job) - When the arm is out of anatomical position, there is less contact between the two bones → if force is applied, the humerus can easily be dislocated out of the socket Link to muscles ● The muscles can only perform movements in the way that the joint was designed ● E.g. muscles that flex, muscles that extend,… Term Definition Syn Together Syndesmos Binding Gomphos Tooth, peg Symphysis Grow together Synovial With egg Labrum Lip