Support and Movement

Definition: Framework of hard structures (bones/cartilage) that provides support and protection. Living tissue capable of growth and repair.

• Endoskeleton: Skeleton inside the body (e.g., Humans).
• Exoskeleton: Skeleton outside the body (e.g., Arthropods).

Functions: Support, Protection, Movement, Production of Blood Cells (in marrow), Storage of Minerals (Ca, P).

Structure: Specialized connective tissue. 'Soft bone'. Firm and flexible. Matrix contains collagen fibers and cells called Chondrocytes in lacunae. No blood vessels (nutrients diffuse).

Types:

• Hyaline Cartilage: Most common. Found at ends of long bones, nose, trachea, bronchi.
• Elastic Cartilage: Flexible. Found in external ear (pinna) and epiglottis.
• Fibrous Cartilage: Tough. Found in inter-vertebral discs.

Definition: Hardest connective tissue.

Structure:

• Compact Bone: Outer hard layer. Matrix has collagen and calcium phosphate. Contains Osteocytes in lacunae. Has channels for nerves/blood vessels.
• Spongy Bone: Inner porous layer. Contains bone marrow (site of blood cell formation).

Human skeleton has 206 bones in adults (300 at birth). Divided into:

• Axial Skeleton (80 Bones):
  • Skull: 22 bones (8 Cranial, 14 Facial).
  • Middle Ear Ossicles: 6 bones (3 in each ear).
  • Hyoid Bone: 1 bone in neck.
  • Vertebral Column: 26 bones (Vertebrae). Last 2 (Sacrum, Coccyx) are fused.
  • Rib Cage: 24 Ribs (12 pairs) + 1 Sternum (Chest bone).
• Appendicular Skeleton (126 Bones):
  • Pectoral Girdle: 4 bones (Scapula + Clavicle on each side).
  • Arms: 6 bones (3 in each: Humerus, Radius, Ulna).
  • Hands: 54 bones (Carpals, Metacarpals, Phalanges).
  • Pelvic Girdle: 2 bones (Hip bones).
  • Legs: 8 bones (Femur, Tibia, Fibula, Patella).
  • Feet: 52 bones (Tarsals, Metatarsals, Phalanges).

Definition: Place where two or more bones meet.

Types:

• Fixed Joints: Allow no movement (e.g., Skull sutures).
• Semi-movable Joints: Allow limited movement (e.g., between Vertebrae, Ribs & Sternum).
• Movable Joints: Allow wide range of movement.
  • Hinge Joints: Move in one plane (e.g., Elbow, Knee).
  • Ball-and-Socket Joints: Move in all directions (e.g., Shoulder, Hip).
  • Pivot Joint: Between top two vertebrae (Neck movement).
  • Saddle Joint: Base of thumb.
  • Gliding Joint: Wrist/Ankle bones.

• Ligaments: Tough connective tissue bands helping to hold Bone to Bone at joints. Prevent dislocation.
• Tendons: Tough connective tissue bands joining Muscle to Bone. Transmit pulling force.

Antagonism: The phenomenon where a muscle opposes the action of another. Such muscle pairs are called Antagonistic Pairs (e.g., Biceps and Triceps).

Working of Arm Muscles:

• Flexion: Bending of arm. Biceps (Flexor) contracts, Triceps relaxes.
• Extension: Straightening of arm. Triceps (Extensor) contracts, Biceps relaxes.

Muscle Identification:

• Origin: End of muscle attached to stationary bone.
• Insertion: End of muscle attached to movable bone.

• Osteoporosis: Bones become weak and brittle. Common in old people/women. Causes: Calcium deficiency. Treatment: Balanced diet (Ca/Vitamin D), Estrogen replacement.
• Arthritis: Inflammation of joints. Symptoms: Pain, stiffness, swelling. Types:
  • Osteoarthritis: Cartilage breakdown. Common in elderly/weight-bearing joints.
  • Rheumatoid Arthritis: Autoimmune attack on joints.
  • Gout: Uric acid crystal deposition in joints.
• Arthroplasty: Surgical replacement or realignment of a joint.