2.1 Human Body – The Skeletal System

Key Concepts: Overview of the Skeletal System

• Complex framework providing structure, protection, and movement.
• Consists of bones, joints, and connective tissues (cartilage, ligaments, tendons).
• Adult human skeleton: 206 bones (axial and appendicular).

1. Functions of the Human Skeleton

• Support: Forms rigid framework, maintains shape and posture.
• Protection: Encases and shields delicate internal organs.
• Movement: Bones act as levers, joints as fulcrums; muscles pull on bones.
• Mineral Storage: Reservoir for calcium and phosphorus.
• Blood Cell Production (Hematopoiesis): In red bone marrow.
• Fat Storage: In yellow bone marrow.

2. Axial and Appendicular Skeleton

2.1 Axial Skeleton (80 bones)

• Definition: Forms the central axis of the body.
• Components: Skull, Auditory Ossicles, Hyoid Bone, Vertebral Column, Thoracic Cage (Sternum, Ribs).
• Functions: Supports, protects vital organs, provides attachment points.

2.2 Appendicular Skeleton (126 bones)

• Definition: Bones of the limbs and girdles.
• Components:
  • Pectoral (Shoulder) Girdle: Clavicle, Scapula.
  • Upper Limbs: Humerus, Radius, Ulna, Carpals, Metacarpals, Phalanges.
  • Pelvic (Hip) Girdle: Coxal bones.
  • Lower Limbs: Femur, Patella, Tibia, Fibula, Tarsals, Metatarsals, Phalanges.
• Functions: Movement, locomotion, manipulation.

Bone Classification by Shape

• Long bones: Limbs (femur, humerus); movement, support weight.
• Short bones: Cube-shaped (carpals, tarsals); wrists, ankles.
• Flat bones: Provide protection (skull, ribs, scapula).
• Irregular bones: Complex shapes (vertebrae).
• Sesamoid bones: Small, round, embedded in tendons (patella).

3. Types of Joints

• Definition: Points where two or more bones meet.

Classification by Structure

• Fibrous Joints: Connected by thick connective tissue; little/no movement (e.g., skull sutures).
• Cartilaginous Joints: Bones united by cartilage; limited movement (e.g., between vertebrae).
• Synovial Joints: Fluid-filled capsule; wide range of motion (most common).

Types of Synovial Joints

• Hinge joints: Movement in one direction (e.g., knees, elbows).
• Ball and socket joints: Rotation and movement in almost any direction (e.g., shoulders, hips).
• Pivot joints: Rotation around an axis (e.g., first/second vertebrae in neck).
• Condyloid joints: Circular motion, flexion, extension (e.g., wrist).
• Planar (Gliding) joints: Limited sliding movement (e.g., wrist, ankle bones).
• Saddle joints: Back/forth and side/side movement, no rotation (e.g., base of thumb).

4. Functions of Bones and Joints

• Support: Provides body shape and support.
• Movement: Attachment points for muscles, joints facilitate movement.
• Protection: Protect internal organs.
• Mineral and Fat Storage: Reservoir for calcium, phosphorus, and fat.
• Blood Cell Formation (Hematopoiesis): Bone marrow produces blood cells.

Importance of Good Posture

• Natural way to hold body, minimal strain.
• Reduces aches and pains (back, neck, shoulder).
• Prevents injuries, improves spine health.
• Reduces wear and tear on joints.
• Increases energy levels, enhances confidence.
• Better muscle and joint function.

Role of Calcium-Rich Foods

• Calcium is crucial for strong bones (700mg/day for adults).
• Sources: Dairy products, green leafy vegetables, fish with edible bones, fortified foods, legumes, seeds, nuts.
• Vitamin D: Essential for calcium absorption (oily fish, egg yolks, sunlight).

Exercises to Strengthen Bones and Muscles

• Weight-Bearing Impact Exercises: Walking, jogging, dancing, climbing stairs, hiking, sports.
• Muscle-Strengthening (Resistance) Exercises: Weightlifting, bodyweight exercises (push-ups, squats, lunges).
• Balance Training: Yoga (combines weight-bearing, resistance, and balance).