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Skeletal System Notes

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Skeletal System Notes

  1. 1. Skeletal System
  2. 2. Websites for HEEEELLLPPPP!!! 1. http://www.bio.psu.edu/people/faculty/strauss/anatomy/skel/skeletal. htm 2. http://depts.washington.edu/bonebio/bonAbout/structure.html 3. http://www.leeds.ac.uk/chb/lectures/anatomy3.html 4. http://homepage.mac.com/myers/misc/bonefiles/bonestruct.html 5. http://www.bbc.co.uk/science/humanbody/body/interactives/3djigsa w_02/index.shtml?skeleton 6. http://www.bartleby.com/107/17.html 7. http://sv.berkeley.edu/showcase/pages/bones.html 8. http://www.innerbody.com/image/skelfov.html 9. http://www.medtropolis.com/VBody.asp 10.http://wps.aw.com/bc_martini_eap_4/40/10466/2679495.cw/content/ index.html
  3. 3. 2 Divisions of Skeletal System • Axial skeleton • Appendicular skeleton
  4. 4. Axial Skeleton • 80 bones • Consist of bones in the: – Skull – Vertebral Column – Thorax – Hyoid
  5. 5. Appendicular • 126 bones • Bones in the: – Shoulders – Upper limbs – Lower limbs – Pelvic girdle
  6. 6. 206 Bones????• 24 Ribs • 1 Sternum • 26 Vertebrae • 56 Phalanges • 2 Clavicles • 2 Scapula • 2 Humerus • 2 Radius • 2 Ulna • 2 Femur • 2 Tibia • 2 Fibula • 2 Patella • 22 cranial/facial • 14 Tarsals • 16 Carpals • 10 metatarsals • 10 metacarpals • 2 pelvic bones • 1 hyoid • 6 ear ossicles
  7. 7. Classification of Bones: By Shape • Long bones – longer than they are wide (e.g., humerus) Figure 6.2a
  8. 8. Classification of Bones: By Shape • Short bones – Cube- shaped bones of the wrist and ankle – Bones that form within tendons Figure 6.2b
  9. 9. Classification of Bones: By Shape • Flat bones – thin, flattened, and a bit curved (e.g., sternum, and most skull bones) Figure 6.2c
  10. 10. Classification of Bones: By Shape • Irregular bones – bones with complicate d shapes (e.g., vertebrae and hip bones) Figure 6.2d
  11. 11. Classification of Bones: By Shape • Sesamoid – knee bone (e.g., patella only) Figure 6.2d Patella
  12. 12. Function of Bones • Support – form the framework • Protection – provide a protective case for the brain, spinal cord, and vital organs • Movement – provide levers for muscles
  13. 13. Function of Bones • Mineral storage – reservoir for minerals, especially calcium and phosphorus • Blood cell formation – (hematopoiesis) occurs within the marrow cavities of bones
  14. 14. Gross Anatomy of Bones: Bone Textures • Compact bone – dense outer layer • Spongy bone – honeycomb of trabeculae filled with bone marrow
  15. 15. Spongy Bone • Does NOT contain osteons (structural units) • Made up of trabeculae (irregular latticework) • Btw. spaces of trabeculae is filled with red bone marrow • Only site of RED bone marrow: (Forms blood cells) • Vertebrae • Skull • Hips • Ribs • Sternum • Ends of long bones
  16. 16. Typical Long Bone Structure
  17. 17. Bone Structure – Typical Long Bone • Diaphysis = shaft, yellow bone marrow produced here • Epiphyses = distal & proximal ends • Epiphyseal line = remnant of epiphyseal plate • Periosteum = outer, fibrous, protective covering, essential for bone growth & diameter • Endosteum = inner lining of medullary cavity, contains bone forming cells (osteoblasts) • Articular cartilage = pad of hyaline cartilage on the epiphyses where long bones articulate or join, reduces friction, absorbs shock • Medullary cavity= space w/in diaphysis that contains fatty yellow marrow (produces blood cells)
  18. 18. Structure of Long Bone Figure 6.3
  19. 19. Structure of Long Bone Figure 6.3a
  20. 20. Structure of Long Bone Figure 6.3b
  21. 21. Structure of Long Bone Figure 6.3c
  22. 22. Bone Tissue • mineral salt makes them hard – Magnesium salts – Calcium salts – Phosphorus salts • collagen fibers gives them tensile strength (the maximum stress the bone can handle w/out breaking)
  23. 23. Bone Surface Markings Foramen HOLE through which blood vessels, nerves, or ligaments pass through (ex. Foramen magnum)
  24. 24. Bone Surface Markings Meatus PASSAGE extending within a bone (ex. External auditory meatus)
  25. 25. Bone Surface Markings • Fossa DITCH or shallow depression on a bone (ex. Mandibular fossa of temporal bone)
  26. 26. Bone Surface Markings • Head rounded projection that forms a joint & supported (ex. Head of femur)
  27. 27. Bone Surface Markings • Crest Prominent ridge (ex. illiac crest of pelvic bone)
  28. 28. Chemical Composition of Bone: Organic • Osteo means bone • Osteoblasts – bone-forming cells • Osteocytes – mature bone cells • Osteoclasts – large cells that resorb or break down bone matrix
  29. 29. Microscopic Structure of Bone: Compact Bone
  30. 30. Microscopic Structure of Bone: Compact Bone • Haversian system, or osteon – the structural unit of compact bone
  31. 31. Parts of the Osteon (Haversian System) – Lamella – weight-bearing, column-like matrix tubes composed mainly of collagen
  32. 32. – Haversian, or central canal – central channel containing blood vessels and nerves
  33. 33. – Volkmann’s canals – channels lying at right angles to the central canal, connecting blood and nerve supply of the periosteum to that of the Haversian canal
  34. 34. Microscopic Structure of Bone: Compact Bone • Lacuna – small cavities in bone that contain osteocytes
  35. 35. • Canaliculi – hairlike canals that connect lacuna to each other and the central canal
  36. 36. Hyoid Bone • Only bone that does not articulate directly with another bone • Attachment point for neck muscles and assists during swallowing and speech
  37. 37. Vertebral Column • Formed from 26 irregular bones • Cervical vertebrae – 7 bones of the neck • C1=Atlas • C2=Axis – Thoracic vertebrae – 12 bones of the torso – Lumbar vertebrae – 5 bones of the lower back – Sacrum –5 fused bones – Coccyx- 3-5 fused bones (tailbone)
  38. 38. Vertebral Column Figure 7.13
  39. 39. Bony Thorax (Thoracic Cage) • Functions – Protects the heart & lungs
  40. 40. Comparison of Male and Female Pelves
  41. 41. Developmental Aspects: Fetal Skull • Bones are not fully connected and held together by fontanels • Fontanels – Unossified membranes – 4: anterior, posterior, mastoid, and sphenoid
  42. 42. Developmental Aspects: Fetal Skull
  43. 43. Bone Deposition • Occurs where bone is injured or added strength is needed • Requires a diet rich in – Protein – Vitamins C, D, and A – Calcium – Phosphorus – Magnesium – Manganese
  44. 44. Homeostasis of Bone Tissue Nutrition 1. Vitamin D absorbs calcium in small intestine 2. Vitamin A bone resorption 3. Vitamin C Hardens bones Hormones 1. Growth Hormone (from pituitary gland) stimulates growth 2. Parathyroid  Can increase calcium levels (PTH) 3. Thyroid Can decrease calcium levels (Calcitonin)
  45. 45. Developmental Aspects of Bones • By age 25, all bones are ossified • Until age of 25 osteoblasts dominate • Mid-old age osteoclasts dominate
  46. 46. Developmental Aspects: Old Age • Intervertebral discs become thin • Loss of stature by several centimeters is common after age 55 • All bones lose mass
  47. 47. Ossifications • Intramembranous= forms flat bones • Endochondral= forms all other bones • http://health.howstuffworks.com/adam- 200125.htm • http://commons.bcit.ca/biology/ossification/ files/ossification.html
  48. 48. Intramembranous ossification: FLAT BONES • Mesenchymal stem cells develop into osteoblasts that secrete osteoids that develop into bone tissue • Spongy bone is formed followed by compact bone surrounding medullary cavity
  49. 49. Endochondral Ossification: LONG BONES 1. Cartilage model formed 2. Primary ossification center formed in diaphysis 3. Blood vessels, medullary cavity formed 4. Secondary ossification center formed in epiphysis 5. Compact bone, articular cartilage, and epiphyseal plate take shape
  50. 50. Stages of Endochondral Ossification Figure 6.8 Formation of bone collar around hyaline cartilage model. Hyaline cartilage Cavitation of the hyaline carti- lage within the cartilage model. Invasion of internal cavities by the periosteal bud and spongy bone formation. Formation of the medullary cavity as ossification continues; appearance of sec- ondary ossification centers in the epiphy- ses in preparation for stage 5. Ossification of the epiphyses; when completed, hyaline cartilage remains only in the epiphyseal plates and articular cartilages. Deteriorating cartilage matrix Epiphyseal blood vessel Spongy bone formation Epiphyseal plate cartilage Secondary ossificaton center Blood vessel of periosteal bud Medullary cavity Articular cartilage Spongy bone Primary ossification center Bone collar 1 2 3 4 5
  51. 51. Functional Zones in Long Bone Growth • Growth zone – cartilage cells undergo mitosis, pushing the epiphysis away from the diaphysis “This is how you grow

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