bone health

• the skeleton?

  • 206 bones
  • divided into axial & appendicular
  • variation across - sex, age, ethnicity, physical activity, diet
• functions of bones?

  1. provides support for soft tissue
  2. carries weight of body
  3. provides rigidity
  4. forms levers for movement
  5. provides protection
  6. mineral response
  7. haematopoiesis
  8. endrocrine function
• classification?

  1. long
  2. short
  3. flat
  4. irregular
  5. sesamoid
• anatomy of long bone?

  • diaphysis
  • epiphyses
  • cortical bone
  • periosteum
  • articular cartilage
  • cancellous bone
  • medullary cavity
  • endosteum
  • bone marrow
  • epiphyseal plate
• diaphysis?

  • main shaft like portion
• epiphyses?

  • extremeties of long bone
• cortical bone?

  • dense & ivory like
  • forms external layer of all bones & bulk of diaphysis of lung bones
• periosteum?

  • external dense white fibrous membrane
  • covers bone except at joint surfaces
  • inner vascular layer contains osteoblasts & osteocytes
• articular cartilage?

  • thin layer of hyaline cartilage
  • covers articular surfaces on epiphyses
• cancellous bone?

  • spongy & contains trabeculae - thin process of bone joined to one another like scaffolding
  • arrangement provides structural strength
• medullary cavity?

  • hollow tube in diaphysis
• endosteum?

  • internal membrane
  • line medullary cavity of long bone
  • contains osteoblasts & osteoclasts
• bone marrow?

  • soft & pulpy
  • composed of connective tissue & cells
  • haemopoietic & fat
• auditory ossicles?

  • located in middle ear
  • malleus - incus - stapes
  • connected via synovial joints
  • incoming sound waves make eardrum vibrate
  • causes vibrations to travel through these bones
  • vibrations are amplified
• define ossification?

  • process of cartilaginous/membranous precursors being changed to bone
• factors affecting ossification?

  • parathormone
  • growth hormone
  • thyroxin
  • testosterone
  • oestrogen
• bone remodelling?

  • formation of new bone cells continues after bone is fully grown
  • in childhood ossification occurs at greater rate than reabsorption - results in bone growth
  • at age 35-40 bone reabsorption exceeds bone ossification - thickness of diaphysis decreases & medullary cavity increases
  • cancellous bone replaced every 3/4 yrs
  • compact bones replaced every 10 yrs
• a joint?

  • point of contact between bones & cartilage/bone
• function of a joint?

  1. give skeleton mobility
  2. hold skeleton together
• types of a joint?

  1. fibrous - immovable
  2. cartilaginous - partially moveable
  3. synovial - freely moveable
• rheumatoid arthritis?

  • joints decline over age with autoimmune link
  • chd has link with ra - associated inflammation narrows arteries & increases bp
  • affects auditory ossicle joints similar to every other synovial joint
• rheumatoid arthritis managment?

  causes cardiac problems

  • prednisone - greater build up of plaque on artery walls - stiffer arteries - decreases insulin sensitivity - higher cholesterol
  • tocilizumab - increase cholesterol & NSAIDs interfere with ability to keep blood vessels open
• osteoporosis?

  • this & heart disease have same age related risk factors
  • lower bone density linked to stiffer arteries
  • those with poor bone quality have higher risk of dying from chs
  • more likely to experience sensorineural hearing loss & report tinnitus - degeneration of 3 bones in middle ear & metabolic changes
• hormones?

  • calcitonin - regulates bone density
  • heart hormone - cells in atria produce more calcitonin than in thyroid - reduces atrial scarring - disrupts electrical impulses travelling through atria - causes atrial fibrillation
• bone marrow & diabetes?

  • diabetes causes damage to bone marrow
  • damages blood vessels & increase risk of hd - impairs blood flow to bm - decreases amount of stem cells produced by bm
  • contributes to hearing loss - consequences of vascular damage in ear/neuropathy affecting auditory nerve
• otosclerosis?

  • caused by abnormal bone remodelling in middle ear
  • disrupts ability of sound to travel through middle ear
  • caused by stapes becoming stuck in 1 place & unable to vibrate
• cholesteatoma?

  • abnormal skin growth into middle ear space behind plane of eardrum
  • skin has advanced to an area of mucosa & perimatrix has bone destroying capacities
  • begins with bone erosion & ends with anything upto complete destruction of any parts of ossicular chain in contact with cholesteotoma
  • ossicles have no capacity of self regeneration - discontinuity of ossicular chain repaired with reconstructive surgery
• trauma?

  • head trauma with fractures/displaced bones can cause hearing loss
  • consequences of intracranial injuries dominate in early period after trauma
  • temporal bone fractures can be longitudinal/transverse - manifest itself - bleeding from ear/acute facial paralysis
  • penetrating trauma causes damage to vascular system & can puncture heart itself
  • treatment will need to account for & navigate around bone