What is an articulation?

he place where a bone meets another bone, cartilage, or teeth and categorized based on mobility and stability

Articulations Classified by structure

hat connects the joint?
• Fibrous: Bones held together by dense regular connective tissue (ex: coronal suture)
• Cartilaginous: Bones joined by cartilage (ex: intervertebral discs)
• Synovial: Bones separated by fluid-filled cavity (ex: ball and socket; shoulder joint)

Articulations Classified by function

How (much) does the joint move?
• Synarthrosis: Immobile joint (ex: coronal suture)
• Amphiarthrosis: Slightly mobile joint (ex: pubic symphysis)
• Diarthrosis: Freely moveable joint (ex: hinge; elbow joint)

Articulations Classified by ligaments

Connective tissue structures (dense regular and dense irregular)
that bind bones to each other and thus play an important role in various joints

Structural Classification: Fibrous Joints

Neighboring bones are joined together with a solid mass of dense irregular connective tissue

Structural Classification: Cartilaginous Joints

Bones are connected by cartilage; little to no movement

Structural Classification: Synovial Joints

Joins adjacent bones by a joint capsule that is continuous with
the periosteum of the connecting bones; allows for wide ranges of movement
(diarthroses)

Articular/Synovial capsule, two layers:

1. Outer fibrous layer made of dense regular connective tissue;
strengthens joint
2. Inner synovial membrane; secretes synovial fluid

Articular cartilage:

• Articular surfaces in synovial joints are covered by hyaline cartilage
• Reduces friction and acts as shock absorber

Types of Synovial Joints

1. Plane joints:
2. Hinge joints:
3. Pivot joints:
4. Condylar joints:
5. Saddle joints:
6. Ball-and-socket joints:

1. Plane joints:

uniaxial; side to side movemen

2. Hinge joints:

uniaxial; like hinge of a door

3. Pivot joints:

uniaxial; one bone rotates on its longitudinal
axis

4. Condylar joints:

biaxial; oval, concave surface of one
bone; convex of the othe

5. Saddle joints:

biaxial; joint surfaces resemble saddle
shape

6. Ball-and-socket joints:

multiaxial; spherical head into
cuplike socke

gliding motion

• Simple movement with a limited range
• Flat bones move from side to side and back and forth with one another
• Ex: Intercarpal or Intertarsal joints

angular motion

Increases or decreases the angle between bones
• Flexion
• Extension
• Hyperextension
• Lateral flexion
• Abduction
• Adduction
• Circumduction

rotation motion

In rotation, a bone turns on its
longitudinal axis

• Lateral rotation
• Medial rotation
• Pronation
• Supination

special movement

Movements that only occur at specific
joints
• Depression vs. elevation
• Dorsiflexion vs. plantar flexion
• Inversion vs. eversion
• Protraction vs. retraction
• Opposition

Double-Jointed(ness)

What we think of as being double-jointed is actually
hyper-mobility, the ability to move a joint beyond
the ‘normal’ range of movement

potential cause of Double Jointed(ness)

◦ Abnormal shapes at the ends of bones
◦ Flexibility of ligaments and tendons (hormone/protein-based)
• (differences in sex/race based on collagen)
◦ Muscle tone (or lack of)
◦ Impaired proprioception

osteoarthritis

• Chronic and degenerative, can affect any joint
• Damage to articular (hyaline) cartilage covering bony
surfaces at articulations
• Injury, overuse, genetics
• Most common chronic joint problem

rheumatoid arthritis

• Systemic, autoimmune disease
• Immune system attacks joints leading to inflammation of the
synovium
• Starts in small joints and moves to larger joint

The Temporomandibular Joint (TMJ)

The TMJ is a diarthrotic, synovial (primarily) hinge joint between the condylar process of the mandible and the mandibular fossa of the temporal bone
• The only freely movable joint between skull bones
• Functions:
◦ Depress/Elevate
◦ Protract/Retract
◦ Lateral displacement
◦ Rotation

Atlanto-axial Joint

• Between the first (atlas) and second (axis) cervical vertebrae
• The atlas rotates around the peg-like dens of the axis
• Pivot joint

The Shoulder Joint (Glenohumeral joint)

Ball and socket joint
• Glenoid cavity of the scapula and head of the humerus
• Rotator cuff muscles anchor the humerus to the scapula and provide the
most strength to this joint
• Labrum – ring-shaped hyaline cartilage
that deepens the socket
Movements
• More freedom than ANY other joint
• Flexion/Extension/Hyperextension
• Abduction/adduction
• Medial/Lateral rotation
• Circumduction

What is a Shoulder Dislocation?

Dislocation of the Glenohumeral Joint
• Anterior shoulder dislocation accounts for
approximately 95% of dislocations of the shoulder
• Posterior dislocations are often missed as the pt will keep the
arm internally rotated and ADDucted
• 95% of dislocations are from trauma
• Up to 40% of persons will also have injury to the
axillary nerve

Shoulder Separation

• Dislocation of the Acromioclavicular (AC) Joint (synovial)
• If the strong coracoclavicular ligament is also torn, the upper limb droops
because it is suspended from the clavicle by this ligament.

elbow Radial collateral ligamen

from lateral epicondyle of humerus – blends with

elbow Annular ligament of the radius

encircles and holds the head of the radius in the radial notch

elbow Ulnar collateral ligament:

extends from medial epicondyle to the coronoid process and olecranon of ulna and consists of three bands

the hip

• Intrinsic to the fibrous capsule of the
hip joint
• Iliofemoral (Y ligament of Bigalow)
• Pubofemoral
• Ischiofemoral

The Knee Joint

• Modified hinge joint
• Largest and most complex joint in the body
• Associated ligaments/structures
• Meniscus: fibrocartilage disc (2) between tibia and
femur
• Medial (tibial) and lateral (fibular) collateral
ligaments
• Patellar ligament (not shown here)
• Anterior cruciate ligament (ACL)
• Posterior cruciate ligament (PCL)

Anterior cruciate ligament (ACL)

• Limits anterior translocation
• Anterior, intercondylar tibial plateau → posterior part of lateral
femoral condyle

Posterior cruciate ligament (PCL)

• Limits posterior translocation
• Posterior, intercondylar tibial plateau→ anterior part of medial
femoral condyl

Meniscus

fibrocartilage disc (2) between tibia and
femur
• Medial: C shaped
• Attached to the medial (tibial) ligament
• Lateral: O shape

Anterior Drawer Test

• Pull tibia anteriorly with a flexed knee
• Tests the integrity of AC

posterior Drawer Test

• Push tibia posteriorly with a flexed knee
• Test the integrity of the PC