Articulations and Joint Classifications: Structure, Function, and Movements

Articulation/Joint

Point of contact between two bones, between cartilage and bone, or teeth and bone.

Ex: Elbow

Example of an articulation involving the Humerus and Ulna, and Humerus and Radius.

Ex: Skull bones

Example of articulations involving Frontal and Parietal bones.

Joints classification

Joints can be classified structurally and functionally.

Structural classification

Is there a joint cavity? What types of connective tissue are involved?

Functional classification

What degree of movement is permitted?

Synarthrosis

does not allow any movement

Amphiarthrosis

allows a small amount of movement

Diarthrosis

freely moveable

Fibrous Joints

contains dense regular collagenous CT with no joint space

Cartilaginous Joints

contains cartilaginous CT with no joint space

Synovial Joints

diarthrosis joints that contain a fluid-filled joint space between articulating bones

Fibrous Joint

held together by dense regular CT, very strong, collagen rich, and has no synovial cavity

Sutures

bones of skull with interlocking edges

Gomphosis

teeth

Syndesmosis

adjacent bones linked by strong membrane, e.g., tibia/fibula; radius/ulna

Cartilaginous Joint

held together by cartilage with moderate strength and no synovial cavity

Synchondrosis

bones are joined by hyaline cartilage, e.g., epiphyseal plate; ribs and sternum

Symphysis

bones are joined by fibrocartilage, e.g., pubic symphysis; intervertebral discs

Synovial Joint

diarthrosis with synovial cavity and synovial fluid between bones, supported by ligament

Hinge Joint

permit movement only in one plane, e.g., elbow; knee

Ball and Socket Joint

allows a large range of motion, e.g., hip; shoulder

Articular Cartilage

cartilage found at the ends of bones to help protect the bone tissue

Joint Capsule

connective tissue that envelops/surrounds synovial joints

Synovial Cavity

space between bones containing synovial fluid

Synovial Membrane

lining of synovial cavity that secretes synovial fluid

Synovial Fluid

thick yolk-like fluid that helps reduce friction between cartilage, composed of hyaluronic acid and interstitial fluid

Nonaxial Movement

gliding movement only

Uniaxial Movement

movement in one plane

Biaxial Movement

movement in two planes

Multiaxial Movement

movement around all three planes

Planar Joint

gliding joints that allow short gliding movements, nonaxial

Condyloid Joint

convex surface of one bone fits into a shallow, concave articular surface of another, biaxial

Pivotal Joint

round/pointed bone articulates with a ring formed by a bone/ligament, monoaxial

Saddle Joint

modified condyloid joint with biaxial movement in two planes

Suture

skull

Amphiarthrosis Joint

Slightly movable, connected by collagen fibers or cartilage

Fibrous Syndesmosis

Tibiofibular joint and Radioulnar joint

Diarthrosis Joint

Freely movable, mostly synovial joints

Sprains

Injuries to ligaments ranging from slight (caused by overstretching) to serious (caused by tearing), e.g., tearing the anterior cruciate ligament (ACL) of the knee

Arthritis

A group of inflammatory or degenerative diseases of joints that occur in various forms, characterized by swelling of the joint, pain, and stiffness

Gouty arthritis

Build up of uric acid

Osteoarthritis

Degenerates surface

Rheumatoid arthritis

Autoimmune disease causing inflammation to synovial membrane

Angular Motion

movement changes angle between bones

Flexion

decreases angle, e.g., movement of forearm towards face

Extension

increases angle

Lateral flexion

bending toward the side

Abduction

lateral movement of limb away from midline

Adduction

medial movement of limb towards midline ('add' together)

Rotational Motion

Bone turns on its own long axis

Lateral Rotation

limb rotates away from midline

Medial Rotation

limb rotates towards midline

Pronation

medial rotation of forearm

Supination

lateral rotation of forearm

Depression

inferior movement of body part, e.g., downward movement of mandible to open mouth

Elevation

superior movement of a body part, e.g., Closure of mouth or shrugging of shoulder

Dorsiflexion

movement of dorsal surface of foot or toes toward shin

Plantar Flexion

pointing toes inferiorly, e.g., ballerina on her toes

Inversion

soles of feet turned medially

Eversion

soles of feet turned laterally

Protraction

anterior movement of body part, e.g., sticking jaw (mandible) forward

Retraction

posterior movement of body part, e.g., moving mandible backwards

Fovea

small, pit-like depression

Fossa

shallow depression; in bone, often serves as articular surface

Olecranal

posterior elbow

Popliteal

posterior knee

Sural

calf

Calcaneal

heel

Vertebral

posterior midline

Gluteal

butt

Coronoid Fossa

Anterior-medial depression for coronoid process of ulna

Olecranon Fossa

Posterior depression for olecranon process of ulna

Ulna

Bone of the forearm, medial to radius

Trochlear Notch

articulates with trochlea of humerus

Olecranon Process

prominent posterior bump

Coronoid Process

inferior lip of trochlear notch