Skeletal System

Structure and Function of the Skeletal System

  • The skeletal system supports the body’s shape and acts as a framework.
  • It facilitates movement in conjunction with muscles and joints.
  • Protects internal organs.
  • Components of Movement:
    • Interaction of bones, joints, and muscles is essential for movement.
    • Example: Flexion of the elbow during a bicep curl.

Functions of the Skeletal System

  1. Shape and Framework
    • Provides structure to the body.
  2. Movement
    • Supports mobility through connection with muscles and joints.
  3. Protection
    • Safeguards vital organs.

Composition of the Human Skeleton

  • Total Bones: 206 bones in the adult human skeleton.
  • Types of Bones:
    • Long Bones (e.g., femur): Support body weight and aid movement.
    • Short Bones (e.g., carpals): Provide stability and limited movement.
    • Flat Bones (e.g., skull, scapula): Protect internal organs.
    • Irregular Bones (e.g., vertebrae): Complex shapes for organ protection.

Axial vs Appendicular Skeleton

  • Axial Skeleton: 80 bones that form the central axis of the body (skull, vertebral column, rib cage).
  • Appendicular Skeleton: 126 bones attached to the axial skeleton (shoulders, arms, hips, legs).
    • **Major Connections: **
    • Arms: Connected via shoulder girdle (scapula and clavicle).
    • Legs: Connected via pelvic girdle (femur, tibia, fibula, patella).

Anatomical Position & Directional Terms

  • Anterior: Front of the body.
  • Posterior: Back of the body.
  • Midline: Divides body into equal left and right halves.
  • Lateral: Away from midline.
  • Medial: Toward midline.
  • Superior: Towards the head.
  • Inferior: Away from the head.
  • Superficial: Near the surface.
  • Deep: Far from the surface.
  • Proximal: Closer to point of origin.
  • Distal: Further from point of origin.

Types of Bones with Examples

  1. Long Bones - Support body weight, enable movement. Examples: tibia, fibula, femur.
  2. Short Bones - Cube-shaped, stability. Examples: carpals (wrist), tarsals (ankle).
  3. Flat Bones - Protect organs. Examples: skull, scapula, sternum.
  4. Irregular Bones - Complex shapes, protection. Examples: vertebrae.
  5. Sesamoid Bones - Reinforce tendons. Example: patella.

Classification of Joints

  1. Fibrous Joints (Fixed)
    • Immovable, examples: teeth in sockets.
  2. Cartilaginous Joints (Slightly Moveable)
    • Comprised of cartilage, examples: vertebrae, pubic symphysis.
  3. Synovial Joints (Freely Moveable)
    • Most common type, surrounded by synovial capsule. Examples include:
    • Hinge Joint: Flexion/Extension (e.g., elbow, knee).
    • Pivot Joint: Rotation (e.g., atlas and axis of neck).
    • Ball and Socket Joint: Flexion/Extension/Adduction/Abduction (e.g., shoulder, hip).
    • Saddle Joint: Flexion/Extension/Adduction/Abduction (e.g., thumb).
    • Condyloid Joint: Circular motion (e.g., wrist joint).
    • Gliding Joint: Gliding movements (e.g., intercarpal joints).

Examples of Joint Movements in Sports

  • Hinge Joint: Volleyball player serving.
  • Pivot Joint: Tennis player watching the ball while serving.
  • Ball and Socket Joint: Bowler in cricket.
  • Saddle Joint: Soccer player throwing in.
  • Condyloid Joint: Tennis player swinging racket.
  • Gliding Joint: Soccer player turning foot to kick.