Human muscoskeletal anatomy

• What are the three main tissues of the muscoskeletal system?

  Bone, muscle, connective tissue (cartilage)
• What is connective tissue?

  Tissue that connects, supports, or separates other tissues or organs.

  It has cells embedded in a matrix with fibres of collagen and elastic tissue
• What is cartilage?

  A hard, flexible connective tissue
• What are the properties of cartilage?

  • Rigid so it can hold open tubes, such as the trachea and bronchi
  • Flexible so it permits movement of the ribcage
  • Returns to its original shape after bending so has a role at the joints and hips
• What are the cells in cartilage?

  Chondrocytes
• Where are chondrocytes founding cartilage?

  In spaces in the matrix called lacunae
• Why does cartilage take a long time to heal?

  No blood vessels so nutrients and gases must diffuse into the matrix which is a slow process
• What is hyaline cartilage?

  • Weakest from of cartilage
  • Found in the joints, nose, larynx, trachea and bronchi
  • High proportion of collagen surrounded by a fibrous coat of connective tissue called the perichondrium
• What is white fibrous cartilage?

  • Strongest form of cartilage
  • Makes intervertebral discs and ligaments
  • Its collagen is ordered in dense fibres so greater tensile strength
• What is Yellow elastic cartilage?

  • intermediate strength
  • Found in the ear pinna and epiglottis
  • Collagen and chondrocytes with are surrounded by a network of fibres called elastin
• What are the functions of the bone?

  • Structural support
  • Movement - attachment site for muscles
  • Protection of organs
  • Blood cell production
  • Mineral regulation e.e storage of calcium and phosphorus
• What is spongy bone?

  • Found at the end of long bones and the vertebrae
  • Has a network of spaces containing bone marrow where blood cells are made
• What is compact bone?

  • Surrounds most bones giving them their white shiny appearance
  • 30% is organic, mainly collagen fibres resisting fracture
  • 70% is inorganic, mainly hydroxy apatite which is very hard and resists compression
• What happens when hyaline cartilage is damaged?

  It is related by fibrocartilage scar tissue
• What are osteoblasts?

  Cells that continually build up the bone
• What are osteoclasts?

  Cells that continually degrade the bone
• What are Haversian systems?

  The structural and functioning unit of the compact bone also known as the osteon
• What do volksmavns canals do?

  Carry blood vessels from the bone surface through to the Haversian canal in the centre of each Haversian system
• What do Haversian canals do?

  They contain nerve fibres and blood vessels to transport nutrients and waste
• What are lamellae?

  Concentric rings around the Haversian canals that are made by the hydroxy apatite which is secreted by the Osteoblasts
• Where are osteocytes (bone cells) found?

  In lacunae within the bone matrix.
• What are canaliculi?

  Small channels that radiate out of the lacunae into the bone lamellae. They contain fluid and processes from the osteoblasts
• How do osteoblasts receive nutrients and remove their waste?

  • The matrix of the lamellae is slightly permeable so oxygen and nutrients can diffuse from the blood through the bone into the cells
  • The fluid and processes from the osteoblasts in the canalculi exchange materials
• What are Haversian systems separated by?

  Interstitial bone
• What are osteocytes?

  Osteoblasts embedded in the Haversian systems
• What is ossification?

  Bones formed from the hyaline cartilage in the embryo . These bones are called cartilage bones and include the limbs, the vertebrae and the ribs
• What happens during ossification?

  • Cartilage cells flatten
  • Calcium salts are deposited
  • Osteoblasts secrete layers of bone matrix around the cartilage
  • Osteoclasts break the cartilage down
  • Blood vessels invade
• Where does ossification begin?

  A the caps at the ends (epiphyses) and in the middle (diaphysis).

  The cartilage remaining allows for growth but is eventually ossified.
• What is the periosteum?

  A dense fibrous connective tissue that surrounds the bone
• What are membrane bones?

  Bones that form directly in the embryo e.g. clavicle, cranium and facial bones
• What is rickets?

  A childhood disease in which calcium is not absorbed into bones making them soft and weak and sometimes deformed
• What is osteomalacia?

  The same as rickets but for adults- bones do not absorb enough calcium making them soft and weak and sometimes deformed
• What causes rickets and osteomalacia?

  A lack in vitamin D or calcium:

  Increased use of sunblock

  Not enough sunlight

  Breastfed babies may not receive enough vitamin D
• How is osteomalacia and rickets prevented?

  • Exposure to sunlight
  • Good amount of calcium in diet
• What is brittle bone disease?

  An inherited disorder in the balance of the organic and inorganic components of bone, leading to an increased risk of fracture
• What is brittle bone disease also known as?

  Osteogenesis imperfecta
• What causes brittle bone disease?

  A mutation replaces glycine in collagen with bulkier amino acids so it cannot coil as tightly and the collagen cannot coil as tightly and so hydrogen bonds are weaker. This means the way collagen interacts with hydroxy appatite is altered making the bone brittle
• What are the treatments of osteogenesis imperfecta?

  • Drugs to increase bone mass
  • Surgery in severe cases
  • Physiotherapy to strengthen muscles
• What is osteoporosis?

  The abnormal loss of density in spongy and compact bones making bones more fragile and more susceptible to fracture
• What are the risk factors of osteoporosis?

  • Age
  • Family history
  • Inflammatory conditions e.g. rheumatoid arthritis
  • Medical conditions that might affect hormone levels
  • Alcohol use
  • Smoking