Joints

I. Joints = articulations – where one bone meets another A I. Joints = articulations – where one bone meets another A. Hold skeleton together while allowing flexibility

II. Functional classifications – amount of movement A. Synarthroses – immovable joints (ex. skull) B. Amphiarthroses – slightly movable (usually axial skeleton) C. Diarthroses – freely movable (usually appendicular skeleton)

III. Structural classifications A III. Structural classifications A. Fibrous joints – bones united by fibrous tissue 1. Sutures of the skull 2. Syndesmoses – ex – connect tibia and fibula

B. Cartilaginous joints – bones connected by cartilage 1 B. Cartilaginous joints – bones connected by cartilage 1. Slightly movable – ex. vertebrae

C. Synovial joints – bones separated by a joint cavity containing synovial fluid, very flexible

A. Articular cartilage-covers the end of the bones Features of Synovial Joints A. Articular cartilage-covers the end of the bones B. Fibrous articular capsule – pocket of connective tissue lined with synovial membrane C. Joint cavity – contains lubricating synovial fluid D. Ligaments – reinforce structure, give strength

E. Other structures 1. Bursae – flattened fibrous sacs lined with synovial membrane, containing synovial fluid – reduce friction 2. Tendon sheath – elongated bursa to protect a tendon

V. Shapes of synovial joints A V. Shapes of synovial joints A. Plane joint – articular surfaces are flat 1. Allows gliding movements 2. Ex. between carpals

B. Hinge joints – cylinder fits into a trough 1 B. Hinge joints – cylinder fits into a trough 1. One- direction movement 2. Ex. elbow, phalanges

C. Pivot joints – rounded end fits into a ring 1 C. Pivot joints – rounded end fits into a ring 1. Bone can turn around its long axis 2. Ex. lower arm, neck

D. Condyloid joint – egg shaped surface of one bone fits into oval concavity of other 1. Allow side-to-side and back and forth movement 2. Ex. wrist, ankle

E. Saddle joints – two saddle cupping each other 1 E. Saddle joints – two saddle cupping each other 1. Allow side-to-side and back and forth movement 2. Ex. Thumb

F. Ball-and-socket joints – spherical head into round socket 1 F. Ball-and-socket joints – spherical head into round socket 1. Allow movement in all directions 2. Ex. hip, shoulder