Human Skeleton Overview Quiz

Skeletal System Overview

• The skeletal system comprises 206 bones.
• Functions include:
  • Movement: Facilitates mobility.
  • Protection and Support: Safeguards internal organs and provides structure.
  • Shape: Maintains body form.
  • Storage of Minerals: Stores calcium and phosphorus.
  • Production of Blood Cells: Produces red and white blood cells in bone marrow.

Types of Bones

• There are four types of bones:
  • Long Bone: Longer than they are wide (e.g., femur).
  • Short Bone: Cube-shaped (e.g., carpals).
  • Flat Bone: Thin and flattened (e.g., skull).
  • Irregular Bone: Complex shapes (e.g., vertebrae).

Joints and Connective Tissues

• A joint is where two or more bones meet.
• Cartilage cushions joints and prevents bone friction.
• Ligaments connect bones, maintaining joint stability.
• Tendons link muscles to bones, facilitating movement.

Joint Types

• Three primary joint types:
  • Fibrous Joints: Immovable.
  • Cartilaginous Joints: Partially movable.
  • Synovial Joints: Freely movable; most common type in the body.

Synovial Joint Variations

• Types of synovial joints include:
  • Pivot Joint: Allows rotation (e.g., neck).
  • Hinge Joint: Allows bending (e.g., elbow).
  • Ball-and-Socket Joint: Allows multidirectional movement (e.g., shoulder).
  • Saddle Joint: Allows angular movement (e.g., thumb).
  • Condyloid Joint: Allows movement in two planes (e.g., wrist).
  • Gliding Joint: Allows sliding (e.g., between vertebrae).

Movement Types

• Flexion: Bending that decreases the angle at a joint.
• Extension: Straightening that increases the angle at a joint.
• Adduction: Movement towards the body's midline.
• Abduction: Movement away from the body's midline.
• Rotation: Circular movement around an axis.
• Circumduction: Circular movement extending from a joint (e.g., shoulder).
• Plantarflexion: Foot movement away from the shin (pointing toes).
• Dorsiflexion: Foot movement towards the shin.

Muscular System Overview

• The human body has over 630 skeletal muscles.
• Functions of the muscular system:
  • Facilitates Movement: Powers physical actions.
  • Maintains Posture: Keeps body aligned.
  • Circulates Blood: Aids in pumping blood.

Muscle Types

• Three muscle types:
  • Skeletal Muscle: Voluntary, attached to bones.
  • Smooth Muscle: Involuntary, found in internal organs.
  • Cardiac Muscle: Involuntary, located in the heart.

Skeletal Muscle Fibres

• Three types of skeletal muscle fibres:
  • Type I (Slow-Twitch): Endurance, oxygen-efficient, resistant to fatigue.
  • Type IIa (Fast-Twitch Oxidative): Combination of aerobic and anaerobic metabolism, suited for mid-distance activities.
  • Type IIx (Fast-Twitch Glycolytic): Primarily anaerobic, best for short bursts of speed and power.

Muscle Function and Movement

• Deltoids raise arms in various directions.
• Abdominals flex the spine, allowing forward bends.
• Biceps bend the arm at the elbow.
• Quadriceps extend the leg at the knee.
• Latissimus Dorsi pulls the arm down and behind.
• Pectorals raise and draw arms across the chest.
• Triceps straighten the arm at the elbow.
• Trapezius supports shoulder movement and head rotation.
• Gastrocnemius allows standing on tiptoes by straightening the ankle.
• Hamstrings bend the leg at the knee.
• Gluteal Muscles assist in hip movement.

Muscle Connections

• Muscles are attached to bones by tendons.
• The origin is the fixed attachment point of a muscle.
• The insertion is where the muscle attaches for movement.

Muscle Action

• Antagonistic Muscle Action: One muscle (agonist) contracts while the opposing muscle (antagonist) relaxes.
• Example: Biceps and Triceps.
• Concentric Contraction: Muscle shortens, bringing origin and insertion closer (e.g., pulling up).
• Eccentric Contraction: Muscle lengthens as it contracts (e.g., lowering in a jump).
• Isometric Contraction: Muscle maintains constant length with no movement (e.g., holding a position).