BackJoints, Joint Types, and Movements: Medical Terminology Study Notes
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Joints and Movements
Types of Joints
Joints, also known as articulations, are contact points between two or more bones, held together by ligaments. Understanding the types and movements of joints is essential for describing the skeletal system and its functions.
Joints (Articulations): Contact points between two or more bones, held together by ligaments (strong bands of connective tissue).
There are three main classes of joints based on movement allowed:
Synarthrosis: Immovable joint (e.g., skull sutures).
Amphiarthrosis: Slightly movable joint (e.g., between vertebrae).
Diarthrosis: Freely movable joint (e.g., shoulder, knee).
Recall: The prefix arthro- refers to joints.
Joint Type | Movement | Example |
|---|---|---|
Synarthrosis | Immovable | Sutures of the skull |
Amphiarthrosis | Slightly movable | Intervertebral discs |
Diarthrosis | Freely movable | Shoulder, knee |
Example: Rheumatoid arthritis is a chronic autoimmune disease causing pain when joints move. The joint type most likely affected is diarthrosis (freely movable joints).
Joint Movements
Terms Describing Movements at Diarthroses
Movements at diarthroses (freely movable joints) are described using specific anatomical terms. These terms help in accurately describing body movements.
Movement | Description | Illustration | Movement | Description | Illustration |
|---|---|---|---|---|---|
Abduction | Moving body part away from midline | Arms raised sideways | Pronation | Turning palm downward | Forearm rotation |
Adduction | Moving body part toward midline | Arms lowered to sides | Supination | Turning palm upward | Forearm rotation |
Flexion | Decreasing angle between bones | Bending elbow | Retraction | Moving body part posteriorly | Jaw pulled backward |
Extension | Increasing angle between bones | Straightening elbow | Protraction | Moving body part anteriorly | Jaw pushed forward |
Dorsiflexion | Pulling top of foot upward | Foot toward shin | Circumduction | Moving limb in a circle | Arm circles |
Plantar Flexion | Pointing foot downward | Standing on tiptoes | Rotation | Turning bone around its axis | Head turning |
Eversion | Turning sole of foot outward | Foot movement | Inversion | Turning sole of foot inward | Foot movement |
Protraction: Moving a body part anteriorly (e.g., pushing jaw forward).
Retraction: Moving a body part posteriorly (e.g., pulling jaw backward).
Example: Protraction is moving a body part anteriorly, while retraction is moving a body part posteriorly.
Matching Joint Movements
Movement decreasing angle between two bones at a joint: Flexion
Turning foot so that sole is pointing outward: Eversion
Pulling top of foot upward toward the shin: Dorsiflexion
Turning forearm upwards: Supination
Additional info: Understanding joint types and movements is essential for describing musculoskeletal disorders, physical therapy, and anatomical function in medical terminology.
