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Articulations Chapter 8. Classification of Joints (Articulations): Joint- Where two bones interact Three functional classes of joints Synarthroses Immovable – e.g., sutures Amphiarthroses Slightly movable – e.g., pubic symphysis, distal radius/ulna Diarthroses
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Classification of Joints (Articulations): Joint- Where two bones interact Three functional classes of joints Synarthroses Immovable – e.g., sutures Amphiarthroses 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
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 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