The musculoskeletal system


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A PPT presentation about the musculoskeletal system that I have prepared for my students of 3rd of ESO

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The musculoskeletal system

  1. 1. THE MUSCULOSKELETAL SYSTEM Bones, joints and muscles Tendons, ligaments and cartilage
  2. 2. The human skeleton • Contains 206 bones •Initially: flexible cartilage •Ossification
  3. 3. Process of ossification• Approximately 20 years• Growth plates• Bone building: - Osteoblasts - Osteocytes - Osteoclasts• Video 25.htm
  4. 4. Structure of bonesCompact bone• Outside part of the bone• Extremely strong and hard• PeriosteumSpongy bone• Mesh-like network (trabeculae)• Red marrow (blood cells)• Yellow marrow (fat)
  5. 5. Micrographs
  6. 6. Anatomical classification of bones• Bones are characterized anatomically as: – long bones (e.g. humerus, femur) – flat bones (membrane bones) – irregular bones (such as the vertebrae)• All these bone types, regardless of their anatomical form, are composed of both spongy and compact bone.
  7. 7. Functions of the skeleton • Bone provides the internal support of the body and provides sites of attachment of tendons and muscles, essential for locomotion. • Bone provides protection for the vital organs of the body: the skull protects the brain; the ribs protect the heart and lungs. • The hematopoietic bone marrow is protected by the surrounding bony tissue. • The main store of calcium and phosphate is in bone. Bone has several metabolic functions especially in calcium homeostasis. •
  8. 8. Joints• Meeting of two bones• Make the skeleton flexible• Types: - Immovable or fibrous - Partially movable, or cartilaginous - Freely movable, or synovial
  9. 9. Joints• Types of synovial joints: - Hinge: knees and elbows - Gliding: wrists and ankles - Ball and socket: hips and shoulders - Pivot: Head
  10. 10. Joints consist of the following:•Cartilage: the bones are covered with cartilage (a connectivetissue), which is made up of cells and fibers and is wear-resistant. Cartilage helps reduce the friction of movement.•Synovial membrane: a tissue that lines the joint and seals itinto a joint capsule. The synovial membrane secretes synovialfluid (a clear, sticky fluid) around the joint to lubricate it.•Ligaments: strong ligaments (tough, elastic bands ofconnective tissue) surround the joint to give support and limitthe joints movement.
  11. 11. Joints consist of the following (II)• Tendons: tendons (another type of tough connective tissue) on each side of a joint attach to muscles that control movement of the joint.• Bursas: fluid-filled sacs, between bones, ligaments, or other adjacent structures help cushion the friction in a joint.• Synovial fluid: a clear, sticky fluid secreted by the synovial membrane.• Meniscus: a curved part of cartilage in the knees and other joints.
  12. 12. Synovial joints
  13. 13. The Muscles• Pull on the joints, allowing us to move.• Help the body perform other functions.• More than 650 muscles ( half of a persons body weight)• Tendons: tough, cord-like tissues• 3 different kinds of muscle
  14. 14. How do muscles move?• Contracting and relaxing.• Work in pairs of flexors and extensors.• The flexor contracts to bend a limb at a joint.• The extensor contracts to extend or straighten the limb at the same joint.
  15. 15. How do skeletal muscles work?