(1) How are bones hinged together?
• Joints: Connection between two bones.
– Filled with cartilage (padding)
• Types of Joints:
– Pivot
– Condyloid
– Plane
– Hinge
– Saddle
– Ball-and-socket

(2) What is the purpose of Joints?
• Allow for wider range of movement.
– Circular
– Angular
• Reduce rigidity of bone structure.

• Rounded end of one bone, protrudes into a sleeve of another bone.
• Movement = Uniaxial Rotation of one bone
• Location = Vertebral Column (allowing head movement side to side “no”) and between the radius and ulna.

• Rotation along two axes (x and y)
• Oval surface of one bone fits into the depression of another bone
• Movement = Angular motion (flexion, extension, abduction, adduction, circumduction)
• Location = Wrist and knuckles

• Straight gliding along 2 horizontal axes
• Movement = short gliding
• Location = Intercarpal and Intertarsal joints and vertebral

• One bone is cylindrical, and fits into the trough shape of the other bone
• Movement = uniaxial hinge (flexion and extension)
• Location = elbow and interphalangeal joints

• Similar to condyloid, but with greater freedom of movement.
• Both bone surfaces are shaped like a saddle.
• Movement = angular motions (flexion, extension, abduction, adduction, circumduction)
• Location = thumbs and metacarpal joints

• Rotation along 3 different axes.
• One bone is spherical and fits into the cuplike socket of the other bone.
• Movement = Universal (all types)
• Location = shoulder and hips

• Sprains:
– Ligaments reinforcing a joint are stretched or torn
– If torn badly, can be replaced with muscle
– Usually result from inflexibility or irregular movement
• Dislocations:
– Bones are forced out of alignment
– Usually result from serious falls and contact sports
– Results in stretching of joint ligaments, leading to future dislocations