The Functions of the Skeletal System Bone Classification Bone Structure

1. The Functions of the Skeletal System • Bone Classification • Bone Structure • Bone Formation and Development • Fractures: Bone Repair • Exercise, Nutrition, Hormones, and Bone Tissue • Calcium Homeostasis: Interactions of the Skeletal System and Other Organ Systems

2. SKELETAL SYSTEM

3. I’m all about the osseous tissues. That’s why I play the Trom-bone.

4. Osseous Tissue and the Skeletal Structure The skeletal system includes: Bones of the skeleton and associated cartilages Ligaments and other connective tissues that stabilize and/or connect them

5. Primary Functions • Framework: support the body’s muscle fat, and skin (soft tissues). • Protection: Surround vital organs to protect them Examples • Skull that surrounds brain • Ribs that protect heart and lungs. • Levers: attach to muscles to help provide movement • Produce blood cells: produce red and white blood cells and platelets. • Storage: store most of body’s calcium, supply blood

6. Structure of bone • Matrix of Bone: 1/3 of bone weight is collagen fibers 2/3 of bone weight is calcium phosphate -Combination of the two provides strong bones which are somewhat flexible and resistant to shattering.

7. Cells in Bones

8. Terms • chondro refers to cartilage • chondrocyte • endochondral • perichondrium • osteo refers to bone • osteogenesis • osteocyte • periostium • blast refers to precursor cell or one that produces something • osteoblast • cyte refers to cell • osteocyte

9. Osteocytes= mature bone cells • recycle the calcium salts in the matrix around them • participate in the repair of damaged bone

10. Osteoblasts= responsible for the production of new bone. (osteogenesis) • Elevated local concentrations of calcium phosphate favorable for calcification

11. Osteoclasts= giant cells with 50 or more nuclei. • Derived from circulating monocytes (phoagocytic white blood cells) • Important in the regulation of calcium and phosphate concentrations in body fluids Osteoclast dissolving bone

12. Osteoprogenitor= mesenchymal cells that maintain populations of osteoblasts and play an important role in fracture repair

13. Classification of Bones By Shape

14. Long Bones- A long bone is one that is cylindrical in shape, being longer than it is wide. Long bones function as levers; they move when muscles contract. • Examples: humerus, ulna, radius, femur, tibia, fibula). • Keep in mind, however, that the term describes the shape of a bone, not its size.

15. Flat Bones- typically thin and often curved. Serve as points of attachment for muscles and often protect internal organs. • Examples include the cranial (skull) bones, the scapulae (shoulder blades), the sternum (breastbone), and the ribs. Flat bones

16. Short Bones- Short bones are approximately equal in length, width, and thickness • Examples: • The bones in the wrist and ankle

17. Irregular Bones- Bones that do not fall into the category of long, short, or flat are considered irregular bones. Examples: • The vertebrae and some of the skull bones are irregular.

18. Sesamoid bones- are small and round, and are located in tendons. • Examples: • patellae

19. How Many Bones Does an Adult Have?

20. 206

21. How Many Bones Does a New Born Baby Have?

22. 270

23. Divisions of the skeletal system

24. Axial Skeleton (Anterior) • Creates the central axis of the body • Includes: • Skull • Thorax • Vertebral column • Contains 80 bones (~40% of skeleton)

25. Skull, Pelvis, and Vertebral columns are STRUCTURES NOT BONES!

26. Appendicular Skeleton 126 bones The bones of the limbs The pectoral girdle The pelvic girdle

27. Vertebral Column “Backbone” Central axis of skeleton 5 regions: Cervical vertebrae (C1-C7) Thoracic vertebrae (T1-T12) Lumbar vertebrae (L1-L5) Sacral (S) Coccygeal bone (CO) Different regions have special characteristics however all have common features *NOTE THE vertebrae numbering/identification! **HINT! HINT!**

29. Ribs & Costal Cartilages 12 pairs (24 total) One pair articulated with each thoracic vertebrae 7 True ribs – (T1-T7) Attach to sternum via cartilage (vertebrosternal ribs) 5 False ribs – (T8-T12) Do not directly attach to sternum (vertebrocondialribs) 2 Floating ribs – (T11-T12) SUB-TYPE OF FALSE RIB Not attached to sternum at all (vertebral ribs)

30. Upper Limb: Wrist & Hand Wrist – region between forearm and hand 8 carpals Hand – attached to carpals 5 metacarpals 5 digits Numbered 1-5 starting with thumb 3 phalanges per finger (2 on thumb) Proximal; Medial; Distal

31. Sutures- Immovable joints which tie bones firmly together with denser fibrous connective tissue

32. Sutures Lamboidal (λ)- Joins Parietal to Occipital Coronal(crown)-Joins Parietal to frontal Sagittal- joins the two parietal plates Squamosal (scale-like)- Joins temporal to occipital and parietal

33. Bone Markings • Bulges, depressions, and holes that serve as sites of attachment for muscles, ligaments, and tendons, joint surfaces, conduits for blood vessels and nerves.

35. Bone Structure

36. Long Bone Flat Bone

37. Bone Structures

38. Compact Bone • Osteon= the functional unit of mature compact bone. (aka Haversian systems/canals) • Within osteon,osteocytes are arranged in concentric layers around the central canal. • Central Canals run parallel to the surface of the bone, contain one or more blood vessels.

39. Isolated osteon: • Nutrients diffuse from vessels in central canal • Alternating direction of collagen fibers increases resistance to twisting forces

40. Spongy Bone • Matrix of spongy bone: • Forms supportive mesh called trabeculae • Seem to align along stress lines • Has no osteonsor blood vessels. Nutrients reach osteocytes by diffusion

41. Gross anatomy of bones

42. Diaphysis is the tubular shaft that runs between the proximal and distal ends of the bone • Medullary cavity- The hollow region in the diaphysis, which is filled with yellow marrow. The walls of the diaphysis are composed of dense and hard compact bone.

43. Epiphysis (plural = epiphyses)- The wider section at each end of the bone, filled with spongy bone. • Red marrow fills the spaces in the spongy bone.

45. Epiphyseal plate (growth plate)-narrow area where the epiphysis meets the diaphysis .Made of a layer of hyaline (transparent) cartilage in a growing bone. • When the bone stops growing in early adulthood (approximately 18–21 years), the cartilage is replaced by osseous tissue and the epiphyseal plate becomes an epiphyseal line.

47. The outer surface of the bone is covered with a fibrous membrane called the periosteum (peri- = “around” or “surrounding”). The periosteum contains blood vessels, nerves, and lymphatic vessels that nourish compact bone. WARNING NEXT SLIDE IS GRAPHIC

49. The medullary cavity has a delicate membranous lining called the endosteumwherebone growth, repair, and remodeling occur. • (endo- = “inside”; oste- = “bone”),

50. Tendons and ligaments also attach to bones at the periosteum. The periosteum covers the entire outer surface except where the epiphyses meet other bones to form joints.