Body Movements in Anatomy

Body Movements

• Flexion: Bending two surfaces toward each other
• Extension: Bending two surfaces away from each other
• Abduction: Movement away from the midline
• Adduction: Movement towards the midline
• Internal Rotation: Turning a part of the body to face inward, towards the midline
• External Rotation: Turning a part of the body to face outward, away from the midline
• Circumduction: Circular movement
• Rotation: Turning on a single axis
• Supination: Lateral rotation of the forearm, leaving the palm forward and thumb away from the midline
• Pronation: Medial rotation of the forearm, leaving the palm backward and thumb pointing toward the midline
• Opposition: Thumb touching the tip of another finger in the same hand
• Reposition: Returning the thumb to its normal position
• Inversion: Turning the sole of the foot inward
• Eversion: Turning the sole of the foot outward
• Dorsiflexion: Ankle movement bringing the foot toward the shin
• Plantarflexion: Ankle movement pointing the foot downward
• Depression: Mandible movement downward
• Elevation: Mandible movement upward
• Retraction: Mandible movement backward
• Protraction: Mandible movement forward

Joints (Articulations)

• Two or more bones meet together
• Functions:
  • Give skeleton mobility
  • Hold skeleton together

Classification of Joints

• Structural Classification:
  • Fibrous: Bones joined by fibrous connective tissue
  • Cartilaginous: Bones joined by cartilage
  • Synovial: Bones separated by a fluid-filled cavity
• Functional Classification:
  • Immovable (Synarthroses): Fibrous joints
  • Slightly movable (Amphiarthroses): Cartilaginous joints
  • Freely movable (Diarthroses): Synovial joints

Fibrous Joints

• Bones joined by dense fibrous connective tissue
• No joint cavity
• Most are synarthrotic (immovable)
• Types:
  • Sutures
  • Syndesmoses
  • Gomphoses

Sutures

• Between bones of the skull
• Joined with short connective tissue fibers

Gomphosis

• Peg in socket joint
• Only example: Tooth in bony alveolar socket

Syndesmosis

• Bones connected by ligament
• Immovable or slightly movable
• Examples:
  • Inferior tibiofibular joint
  • Interosseus membrane: Between tibia/fibula & ulna/radius

Cartilaginous Joints

• Bones united by cartilage
• Bones connected by fibrocartilage or hyaline cartilage
• No joint cavity
• Types:
  • Primary: (Synchondroses)
  • Secondary: (Symphyses)

Primary Cartilaginous (Synchondroses)

• Bar or plate of hyaline cartilage unites the bones
• Joints are Synarthroses
• Examples:
  • Epiphyseal plates in long bones of children
  • Costal cartilage of the first rib and manubrium of the sternum (1ry → 1st sternocostal joint)

Secondary Cartilaginous (Symphyses)

• Articular surfaces of bone covered with hyaline cartilage fused to a plate of fibrocartilage
• Joints are amphiarthrotic
• Examples
  • Intervertebral joints (discs)
  • Pubic symphysis

Synovial Joints

• Special features:
  • Articular hyaline cartilage
  • Joint (synovial cavity)
  • Fibrous capsule
  • Synovial membrane
  • Synovial fluid

Movements at Synovial Joints

• Range of Movement:
  • Nonaxial—slipping movements only: Plane Joint
  • Uniaxial—movement in one plane: Hinge Joint and Pivot Joint
  • Biaxial—movement in two planes: Condyloid Joint and Saddle Joint
  • Multiaxial—movement around all three: Ball & Socket Joint

Classification of Synovial Joints

• Plane Joint:
  • Nonaxial joints
  • Example: Midcarpal joints
• Hinge Joint:
  • Uniaxial joints
  • Example: Elbow joint
• Pivot Joint:
  • Uniaxial joints
  • Example: Radioulnar joint (Superior)**