Types of Joints and the Anatomy of the Synovial

Joint

What is an Articulation (Joint)

Point of contact between two bones

**There are three types of joints

1. Fibrous Joints Also called “sutures” These joints are bound tightly together

by connective tissue and allows ZERO movement (immovable joint)

Ex. Interlocking bones of the skull

2. Cartilaginous Joints Occur where the body of one bone

connects to the body of another bone by means of cartilage and allows SLIGHT movement

Ex. Intervertebral discs

3. Synovial Joints Occurs where bony surfaces are

separated by a lubricating fluid (synovia) and by cartilage

Also joined by ligaments, which enclose the ends of articulating bones and form the synovial-containing capsule

Allows MOST movement

Examples of Synovial Joints

Knee Ankle

Shoulder

Elbow

Parts of Synovial Joint

1. Articulating Cartilage Allow for smooth contact surface Acts as a shock absorber

2. Joint Cavity Located between two bony articulating

surfaces Filled with synovial fluid (joint lubricant)

Essential in reducing friction and providing nutrients for articulating cartilage

3. Joint Capsule Fibrous structure that consist of the:

Synovial membrane (allows certain nutrients to pass through to synovial fluid)

Fibrous capsule (keeps synovial fluid from leaking)

** Membrane is medial to capsule

4. Bursae Small flattened sacs Prevents friction between tendons,

ligaments and bones

Intrinsic Ligaments Thick bands of fibrous connective tissue Helps thicken and reinforce the joint

capsule Ex. Forming the joint capsule or the

meniscus of the knee

Extrinsic Ligaments Separate from the joint capsule and

help to reinforce the joint by attaching bones together

Types of Synovial Joints

Gliding Joint Also known as a “plane” or “arthrodial”

joint Connects flat or slightly curved bone

surfaces Ex. Joints between tarsals Ex. Joints between carpals

Hinge Joints Also known as a “ginglymus” joint Think of the hinge of a door… Convex portion of one bone fitting into a

concave portion of another Allows movement on one plane Ex. Joint between phalanges Ex. Joint between humerus and ulna Ex. Joint between femur and tibia

Pivot Joints Also known as a “trochoid” joint Allows rotation in one plane (uni-axial) A rounded point of one bone fits into a

groove of another Ex. Atlantoaxial joint (between atlas and

axis– shake head “no”) Ex. Between radius and ulna at humerus

Ellipsoid Joints Allows movement on two planes (bi-

axial) Ex. Metaphalangeal joint

Saddle Joints Allows movement in two planes Movements include flexion/extension

and abduction/adduction Does not have a ball-and-socket rotation Ex. Carpo-metacarpal articulation

Ball and Socket Joint Also known as a “spherodial” joint “Ball” at one bone fits into the “socket”

of another, allowing movements around all three axis

Ex. Hip Ex. Shoulder