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Articulations
Chapter 8
Classification of Joints (Articulations):
Joint- Where two bones interact
 Three functional classes of joints

Synarthroses


Amphiarthroses


Immovable – e.g., sutures
Slightly movable – e.g., pubic symphysis, distal radius/ulna
Diarthroses

Freely movable – e.g., shoulder, elbow etc.
 Classification of Joints (Articulations):
 Three structural classes of joints

Fibrous
No space between articulating bones; held together by
dense connective tissue – e.g., sutures, distal radius/ulna
 May be functionally synarthroses or amphiarthroses


Cartilagenous
No space between articulating bones; held together by
cartilage – e.g., pubic symphysis
 May be funtionally synarthroses or amphiarthroses


Synovial
Space (synovial/joint cavity) between articulating bones –
e.g., shoulder, elbow etc.
 Functionally are diarthroses

The Structure of Synovial Joints
The Structure of Synovial Joints
Major synovial joints in the body
• spinal (e.g. cervical and lumbar)
• shoulder (glenohumeral)
• elbow
• proximal radio-ulnar
• wrist
• fingers
• hip
• knee
• ankle/foot
• toes
• temporomandibular (TMJ)
Movements occurring at synovial joints
Flexion
Extension
Hyperextension
Lateral flexion
Abduction
Adduction
Rt. lateral flexion
Lt. lateral flexion
Rotation:
Left/Right
Medial (internal)
Lateral (external)
Pronation
Supination
Dorsiflexion/Plantarflexion
Inversion/Eversion
Elevation/Depression
Protraction/Retraction
Opposition
Movement at synovial joints
occurs through the activity of
skeletal muscles
Anatomy of skeletal muscles
Anatomy of the Muscular System
• Origin - Muscle attachment that remains
fixed
• Insertion - Muscle attachment that moves
• Action - What movement a muscle
produces. Movement usually occurs at
joints i.e. flexion, extension, abduction,
etc.
• For muscles to create a movement,
they can only pull, not push
• Muscles in the body rarely work alone,
& are usually arranged in groups
surrounding a joint
• A muscle that contracts to create the
desired action is known as an agonist or
prime mover
• A muscle that helps the agonist is a
synergist. Some synergists act as
fixators
• A muscle that opposes the action of the
agonist, therefore undoing the desired
action is an antagonist
Skeletal muscle movements
Flexion/extension
Abduction/adduction
Rotation – left/right; internal(medial)/external(lateral)
pronation/supination
Elevation/depression
Protraction/retraction
Dorsiflexion/plantarflexion
Inversion/eversion
*note: muscles of facial expression (e.g. orbicularis oculi; orbicularis oris)
produce movements of the features of the face, and therefore the actions
use more descriptive terminology