EDUCATION

1. EDUCATION “The purpose of education is to replace an empty mind with an open one.” -Malcolm S. Forbes

2. Chapter 6 The Skeletal System

3. Functions of Bone • __________________________________________ • It provides a framework for the body and gives it shape. • It supports and protects organs from injury. • _______________________________________ • It provides a place for muscles, tendons, ligaments and tendons of the body to attach. • It helps make movement possible. • ____________________________ • It stores minerals (Calcium) • _______________________________ • It provides a place for hematopoeisis

4. Bone Structure • Two main types of bone: • _________________________ Bone • Light and spongy inner layer of bone. • Consists of tiny spicules with bone marrow between. • _________________________ Bone • Heavy and dense outer layer of all bones • Composed of haversian systems (small units of bone tissue)

6. Bone Structure • 3 types of bone cells. • ____________________- cells that secrete the matrix of bone • ____________________- cells that have been trapped in the matrix they have created • _____________________- cells that remodel bone by eating it away from places it is not needed. • ______________________- covering of bone • ______________________- membrane that lines the hollow interior surface of bones.

8. Bone Cells • Osteoblasts • Cells that form bone. • Osteocytes • Osteoblasts that are no longer active & trapped inside matrix of osseous material. • Can revert back to osteoblasts • Osteoclasts • Eat bone away. • Are the remodelers of bone • Withdraw calcium when needed from bone

9. Haversian Systems • Concentric layers of ossified bone matrix arranged around a central Haversian canal

10. Blood Supply to Bone • Tiny vessels penetrate the periosteum. • _________________________- tiny channels in the bone matrix that vessels pass through. • Are at right angles to Haversiancanals • _________________________- Where large vessels enter the bone. • Carry blood into and out of bone marrow. • Can be mistaken for fracture on radiographs.

11. NUTRIENT FORAMINA

12. DIAPHYSIS – the shaft of long bones EPIPHYSIS – the ends of long bones

13. Bone Formation • Bone is formed in 2 ways: • ____________________________ • ____________________________ • Bone formation and growth is stimulated by ____________________(GH) from the anterior pituitary (adenohypophysis) gland in the brain.

14. Endochondral Bone Formation • Endochondral Bone formation • Cartilage to bone formation • How most bones develop • Starts in the ______________________ - ________________ in the diaphysis(shaft) of long bones are gradually replaced by bone. • There are ________________ that develop in epiphysis (ends) of bones

16. Growth plates • Located between ________________and ___________________ • Sites of creation of new bone that allows bone to lengthen as animal grows. • Cartilage is created on epiphyseal side while bone is created on diaphyseal side. • When bone reaches full length, all cartilage is replaced by bone and plates “close”. • Remodeling may take place but bone will not get any longer. • Young animals may have epiphyseal fractures because this area is weaker than rest of bone.

19. Intramembranous Bone Formation • Occurs only in _____________________bones • Bone forms directly from _____________ with no cartilage intermediary.

20. Bone Shapes • Long Bones • Short Bones • Flat Bones • Irregular Bones

21. Long Bones • Longer than they are wide. • The ends of the bones are called _________________________ • There is both a _________ epiphysis and a _____________ epiphysis • Main part of bone is the shaft or _______________ which is composed of compact bone. • EXAMPLES: _____________________________________________________________

22. Short Bones • Shaped like cubes. • Have core of _________________bone covered by _____________________ bone. • EXAMPLES: _____________________________

23. Flat Bones • Thin and flat bones • Consists of two layers of ______________ bone separated by _________________bone. • EXAMPLES: ____________________________________________________________

24. Irregular Bones • Miscellaneous bones that do not fit into another category. • May have characteristics of more than one category. • EXAMPLES:________________________________________ • _____________ - is largest sesamoid bone in body.

26. Bone Marrow • Fills the spaces within center of bones • Has two types: • _______________ bone marrow • ________________________- the process of forming new blood cells. • Majority of bone marrow in young animals but less inolder animals • __________________ bone marrow • Consists primarily of __________________ connective tissue. • Common type of marrow in adult animals • Does not produce blood cells but can revert to red marrow if needed.

28. Common Bone Features • ___________________________ • Joint surfaces where bones come in contact with each other to form joints. • Consists of: • Condyles • Head • Facet • Covered by articular cartilage • Composed of what type of cartilage?

29. Common Bone Features: Condyle • Large, round articular surface. • Major condyle is located on end of humerus and femur. • Also located in skull.

30. Common Bone Features: Head • Somewhat spherical articular surface on the proximal end of a long bone. • Found on humerus, femur and rib. • Head is usually joined with rest of bone by a neck.

31. Femoral Head Ostectomy (FHO) • Head of femur is removed in cases of trauma or severe arthritis. • A “false joint” forms which gives more comfort to the patient.

32. Femoral Head Ostectomy

33. Common Bone Features: Facet • A flat articular surface. • Found in carpal and tarsal bones as well as in vertebrae, radius and ulna.

34. Common Bone Features: Processes • All projections of a bone. • Heads and condyles are considered to be processes. • Tendons may attach to processes

35. Common BoneFeatures: Holes and Depressed Areas • __________________: A hole in bone. • Usually allow the passage of nerve or blood vessel. • May exist simply to lighten structure • Example: pelvis has the ____________________ • ______________: A depressed or sunken area on the surface of a bone. • Usually occupied by muscles or tendons.

37. Types of Skeletons • Bones of head and trunk are _______________________________Skeleton • Bones of limbs and appendages are ____________________________ Skeleton. • Some animals may have __________________- bones formed in the viscera or soft organs.

38. Axial Skeleton:bones of head & trunk Skull Hyoid bone Spinal column Ribs Sternum

39. Skull Usually consists of 37 or 38 separate bones Most skull bones joined by _________________ Mandible is connected to skull by a ______________(TMJ)

40. Skull External bones: • Frontal bones (2) • Occipital bones (1) • Parietal bones (2) • Temporal bones (2) • Incisive (2 ) • Nasal (2) • Maxillary (2) • Zygomatic (2) • Mandible (2) • Palatine (2) • Turbinates (2)

41. Skull Bones Continued • Categorized by: • Bones of Cranium • Bones of the ear • Bones of the face

42. Bones of the Cranium • Cranium-portion of skull that surrounds the brain. • External Bones of Cranium: • Frontal Bones (2) • Interparietal Bones (2) • Occipital Bone (1) • Parietal Bones (2) • Temporal Bones (2) • Internal Bones of Cranium: • Ethmoid Bone (1) • Sphenoid Bone (1)

43. External Bones of Cranium

44. Occipital Bone • Forms caudoventral portion or base of skull, most caudal skull bone. • Important because: • Where spinal cord exits skull • Skull bone that articulates with first cervical (neck) vertebrae. • ______________________is in center of occipital bone. • Occipital Condyles are on either side of foramen magnum

46. Interparietal Bones • Small bones located on dorsal midline between occipital and parietal bones • Clearly visible in young animals, may fuse together in older animals.

47. Parietal Bones • Form the lateral walls of the cranium • Well developed in dogs, cats and humans, but relatively small in horses and cattle.

48. Temporal Bones • Located ventral to the Parietal bones • Form walls of the cranium • Contain middle and inner ear structures • Form ________________________(TMJ’s) with the mandible (Lower jaw)