BONES

1. BONES Chapter 5 – Vertebrate Anatomy

2. Major Functions of Bone • Support • Backbone, etc. • Protection • Skull, ribs • Movement • Levers against which muscles work • Mineral storage • Blood cell formation

3. Two Major Types of Bone • Compact Bone • Spongy Bone

4. Compact Bone • Dense • Smooth and solid in appearance

5. Spongy Bone • Honeycombed • Contains marrow in spaces

6. Bones are Classified by Shape • Long Bones • Short Bones • Flat Bones • Irregular Bones

7. Long Bones • Bones that are longer than they are wide. • Shaft with two ends • Primarily compact bone • Spongy bone at interior • All bones of the limbs are long bones

9. Short Bones • Roughly cubelike in shape • Contain mostly spongy bone • Bones of the wrist and ankle

10. Flat Bones • Thin, flattened and usually a bit curved • Two roughly parallel compact bone surfaces with spongy bone within • Skull bones; scapulae (shoulder blades)

11. Irregular Bones • Bones that fit none of the other classes • Vertebrae • Hip bones (pelvic bones) • These bones have complex shapes • Consist mainly of spongy bone

12. Bones are Organs • Bones are supplied and associated with many other tissues, thus they are organs • Supplied with nerves, blood vessels, lymph vessels • Covered with membranes (epithelial tissues)

13. Structure of a Typical Long Bone • Diaphysis – shaft of the long bone • Thick collar of compact bone surrounds a central marrow cavity • Epiphysis – ends of a long bone • Exterior of epiphyses are formed by compact bone • interior contains spongy bone • Joint surface of each epiphysis is covered with articular cartilage • Epiphyseal line • Remnant of a structure called the epiphyseal PLATE • Epiphyseal plate is the disk-like plate which allows for growth of the long bone during childhood • Cushions opposing bone ends during movement

15. Epiphysis detail • Click here for a detailed view of the epiphysis

16. Structure of Long Bone, cont. • Both internal and external surfaces are covered with membranes • Outer membrane – periosteum • Covers shaft • Richly supplied with blood vessels, nerves, etc. • Vessels enter through holes in the bone called nutrient foramen • Membrane also is anchoring point for tendons and ligaments • Inner membrane - endosteum

17. Structure of Short, Irregular and Flat bones • Simple design • Outside – compact bone • Inside – spongy bone

18. Blood forming tissue in bones • Red marrow • Typically found in cavities of spongy bone in long bones and flat bones • In adults, most blood formation occurs in • Head of femur/humerus • Sternum • Hip bones • In adults, the marrow cavity containing yellow marrow (fat) extends well into the epiphyses of most long bones

19. Chemical Composition of Bone • Both inorganic and organic compounds make up bone • Proper combination of organic and inorganic components allows bones to be durable without being brittle • Organic components • Composed of • Cells • Organic portion of matrix • Provide flexibility and tensile strength (strength under tension) • Inorganic components • Mineral salts • Calcium phosphate is the main mineral salt • Provide hardness

20. Bone Markings • Bones have many bumps, bulges, depressions, holes, etc. • “Bumps” are typically are points for muscle attachment • Holes are typically points for blood vessels or nerves to pass through

21. Terms for Bone Markings • Condyle – smooth rounded projection that allows for articulation • Articulation – usually a place where two bones meet and move against each other, but sometimes no movement occurs. • The image shows the occipital condyles at the base of the skull. These articulate with the first vertebra.

22. Terms for Bone Markings • Crest • A narrow ridge of bone • The images show the sagittal crest of a badger

23. Terms for Bone Markings • Foramen • A hole • Usually for passage of blood vessels and/or nerves

24. Terms for Bone Markings • Process • Any bony prominence or projection • To the right is the mastoid process • Also visible is the styloid process • Both are sites of muscle attachment to the skull

25. Terms for Bone Markings • Spine • A sharp slender process or projection • This photo shows the neural spines on vertebrae of a dinosaur

26. Terms for Bone Markings • Suture • A seam • Irregular lines produced by interlocking bones • An immovable joint • The photo shows sutures of the skull

27. Terms for Bone Markings • Fossa • A depression • Often an articulating surface • May meet with a condyle on another bone

28. Types of Fractures • Simple – • only bone damage – little or no tissue damage • Complete break

29. Types of Fractures • Compound – bone breaks through the soft tissue to the outside • High risk of infection

30. Types of Fractures • Compression • This type of bone fracture generally occurs after a fall where the vertebral column is compressed and then under the extreme pressure cracks or breaks. • Crushing of bone

31. Types of Fractures • Comminuted – more than two fragments of bone broken off.

32. Types of Fractures • Impacted • Ends of bone become wedged together

33. Types of Fractures • Spiral • Fracture caused by twisting force that creates an oblique fracture around and through the bone

34. Types of Fractures • Greenstick • incomplete fracture in which only one side of the bone has been broken.

35. Types of Fractures • Depression

36. Homeostatic Imbalances of Bone • Osteoporosis • Diseases in which bone resorption outpaces bone replacement • Bone marrow becomes porous and lighter • Spine is most vulnerable; also neck of femur • Estrogen and testosterone are important in maintaining normal bone density • After menopause, estrogen secretion in women diminishes and contributes to bone loss • Other causes of bone loss • Lack of exercise • smoking

37. Preventing Osteoporosis • Take calcium beginning at age 35-40 • Drink flouridated water • Do weight bearing exercise

38. Other diseases of bone • Osteomalacia • Bones inadequately mineralized • Rickets • Bones bend/deform • Children mostly affected • Caused by low calcium; vitamin D