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Skeletal System

ST110 Concorde Career College, Portland. Skeletal System. Objectives. Define the term skeleton. Describe the functions of the skeletal system. List and identify the structures of the skeletal system and describe the function of each. Identify the types of bone. Objectives.

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Skeletal System

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  1. ST110 Concorde Career College, Portland Skeletal System

  2. Objectives • Define the term skeleton. • Describe the functions of the skeletal system. • List and identify the structures of the skeletal system and describe the function of each. • Identify the types of bone.

  3. Objectives • List the types of joints and describe the function of each. • List the classifications of bone and provide examples of each. • Describe the processes of bone formation and bone healing.

  4. Objectives • Describe the mechanism by which the skeletal system helps to maintain homeostasis. • Describe common diseases, disorders, and conditions of the skeletal system including signs and symptoms, diagnosis, and available treatment options. • Demonstrate knowledge of medical terminology related to the skeletal system verbally and in the written form.

  5. Skeleton

  6. Introduction • Includes all bones of the body (206) and includes cartilage, tendons, and ligaments • Cartilage – connective tissue that provides a smooth surface for bone movement (articulation) • Ligaments – connective tissue that attaches bone to bone (ligaments also support abdominal organs) • Tendons – connective tissue that attaches muscle to bone • Serves as a framework for the body • Composed of living tissue

  7. Functions • Supports and stabilizes surrounding tissues such as muscles, blood vessels, nerves, fat, and skin • Protects vital body organs such as the brain, spine, heart, and lungs and protects other soft tissues of the body • Assists in body movement by providing attachments for muscles that pull on bones • Matures blood cells • Stores mineral salts (e.g., calcium)

  8. Types of Bone Cells • Osteoprogenitor - Stem cell that is destined to become bone • Osteoblast - Bone building cell • Osteocyte - Mature bone cell • Osteoclast - Resorption (breakdown)

  9. Bone Cells • Osteoprogenitor (osteogenic) Cells: • Stem cells of skeletal tissue • Composes the Inner layer of periosteum and the single layer of endosteum • Functions: formation of fetal bone and repair of fractures • Differentiate into Osteoblasts (good blood supply) and Chondroblasts (limited blood supply)

  10. Bone Cells • Osteoblasts: • form bone matrix • Develop into osteocytes • Osteocytes: • responsible for maintaining bone matrix (develop from osteoblasts) • Osteoclasts: • Breakdown and resorption of bone • Activated by parathyroid hormone • Differentiated from blood monocytes

  11. Bone Cells

  12. Growth and Development • Osseous tissue • Longitudinal growth occurs until the age of 15-16 • Bone maturation occurs around the age of 21

  13. Embryonic Development of Bone • Skeleton is initially composed of cartilage and gradually replaced with bone via two methods • Intramembranous Ossification: Develops flat bones of the cranium, facial bones, Mandible and clavicle • Endochondrial Ossification: long bones, etc. (the rest of the bones) Cartilage > Bone

  14. Embryologic Development

  15. Epiphyseal Plate • Located at the junction between the diaphysis and each epiphysis • Area of growth (allows bone to lengthen) • Around age 16-25 Epiphyseal plate ossifies marking full maturity (end of growth)

  16. Epiphyseal Plate

  17. Epiphyseal Plate

  18. Bone Remodeling • Bones undergo a lifetime of remodeling and adapting to stress • Remodeling maintains bone structure and strength as well as ensures constant supply of calcium to the body • Osteoclasts absorb bone that is then replaced by new compact bone • When low blood calcium levels are detected parathyroid hormone releases and stimulates the osteoclasts. When high blood calcium occurs, calcium is stored in bone. • When normal blood calcium levels are reached the thyroid releases calcitonin. Calcitonin inhibits osteoclasts and stimulates osteoblasts (negative feedback loop)

  19. Factors that Affect Bone Maintinance • Hormonal influence • Exercise: weight-bearing exercise is important in maintaining bone strength • Osteoporosis: results when bone matrix is lost faster then replaced • Nutrition: key factor in maintenance of normal bones • Scurvy: results form a deficiency in vitamin C, shaft of long bone becomes thin and fragile predisposing the person to fractures • Rickets: results form vitamin D deficiency, causes poorly calcified, semiriged bones that bend under bodies weight (bowed legs, knock-knees)

  20. Scurvy

  21. Rickets

  22. Two Types of Bone 1. Cortical - Hard compact bone found in the shaft of long bones and makes up the outer layer of all other bones. 2. Cancellous (trabecular) - Soft spongy bone found at the ends of long bones and at the center of all other bones.

  23. Compact Bone 75% Spongy Bone 25%

  24. Bone Types

  25. Cortical Bone • Dense and strong • Osteon (Haversian System) • Rings of mineral salts that allow bone cell metabolism • Central Canals • Small canals that contain blood vessels • Lamella-surrounds central canals • Lacunae-tiny cavities in between lamella that contain osteocytes

  26. Cortical Bone • Canaliculi-connect the lacunae and central canals Volkmann (perforating) canals-run horizontally and contain blood vessels

  27. Haversian System

  28. Cancellous Bone • Spongy bone • Located at the ends of long bones and forms the center of all other bones • Trabeculae • Meshwork of interconnecting bone secretions • Gives strength to bone • Filled with lamellae and osteocytes

  29. Skeletal System Bone Membranes • Periosteum - Covers the outside of the bone with the exception of the articulating surface and contains osteoblasts for bone growth and repair. • Endosteum - Lines the marrow cavity and also contains growth and repair cells.

  30. Periosteum • Layer of fibrous tissue that surrounds bone • Functions: • Layer of defense to protect from infection • Forms new bone cells • Full of nerves and blood vessels to aid in nourishment of bone • Attachment for tendons and ligaments • **Due to these various functions the orthopedic surgeon will approximate the periosteal layer when incised

  31. Periosteum

  32. Medullary Canal • Canal that runs down the middle of bone • Contains semisolid tissue Red Bone Marrow • Located in the spaces of spongy bone found in the ends of long bones, sternum, vertebrae, and ribs • In adults RBM is replaced with yellow bone marrow • Functions: production of erythrocytes, leukocytes, and platelets • Endosteum: fibrous layer of tissue that lines medullary cavity

  33. Bone Marrow Red Bone Marrow • Fills in spaces in cancellous bone • Richly supplied with blood • Hematopoiesis • Blood cells in all stages of development • Gradually decreases with age

  34. Bone Marrow Yellow Bone Marrow • Contains fat cells • Found in the medullary cavity (canal)

  35. Bone Identification • Shapes • Long • Short • Flat • Irregular • Sesamoid • Markings • Projections • Depressions

  36. Bone Shapes

  37. Long Bones • Length exceeds width • Diaphysis-shaft of mainly compact bone • Thickness • Curvature • Medullary cavity • Femur, radius, humerus

  38. Structure of a Long Bone

  39. Long Bones • Metaphysis-flared portion on each end consisting of spongy bone • Epiphysis-on the end out from the metaphysis consisting of spongy bone • Epiphyseal line (plate - growth)

  40. Short Bones • No long axis • Irregular shaped • Thin layer of compact tissue over cancellous • Carpal bones

  41. Flat Bones • Very thin bones that attach to muscle and/or protect vital areas • Sternum, bones of the skull

  42. Flat Bones

  43. Irregular Bones • Very strange shape • Layers of Compact bone over spongy bone • Ossicles, vertebrae

  44. Irregular Bones

  45. Sesamoid Bone • Small, round • Enclosed in a tendon • Adjacent to joints • Kneecap, patella

  46. Sesamoid Bone

  47. Bone Markings-Processes (projections) • Obvious bony prominence • Types • Spine-sharp, slender projection • Condyle-rounded or knuckle-like prominence • Tubercle-small round process • Trochlea-process shaped like a pulley • Trochanter-very large projection

  48. Bone Markings-Processes • Crest - narrow ridge of bone • Line - a little less prominent ridge of bone • Head - an enlargement at the end of the terminal • Neck - part of a bone that connects the head or terminal enlargement to the rest of the bone

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