1. The Skeletal System
Chapter 6-9

2. Individual bones: Tissues Bone Cartilage Epithelial tissue
Fibrous connective tissue
Blood
Nervous tissue

3. Bone Structure Long bone External structure
Epiphysis, the portion of the bone that interacts with other bones
Articular cartilage, protective layer of hyaline cartilage coating the epiphysis

4. Diaphysis, long narrow portion between epiphyses, AKA: shaft
Hyaline cartilage, most common type of cartilage, looks like “milky glass”
Diaphysis, long narrow portion between epiphyses, AKA: shaft

5. Periosteum, any part of the bone not covered by articular cartilage is protected by this tough fibrous membrane. It is a vascular tissue, functions in bone repair.

6. Internal structure Tissue types:
Compact bone, dense strong and resistant to bending

7. Spongy bone, branching bony plates that create irregular spaces, strong and durable because they allow for some compression.

8. Tissue location
Compact bone makes up the wall of the diaphysis

9. Spongy bone makes up the bulk of the epiphysis especially in regions that are subject to compression, (weight bearing joints)

10. Description: the diaphysis is a semi-rigid hollow structure
Medullary cavity, hollow tube runs from end to end in the open space of the diaphysis

11. Endosteum, lines the cavity
Marrow, specialized, highly functional, soft CT, inside the cavity

12. Microscopic Structure:
Osteocyte, individual compact bone cell, located in…

13. Lacunae, chambers arranged in concentric circles around…
Osteonic canal, pathway for arteries, veins, and nerves through the bone

14. Canaliculus, smaller canals running perpendicular to the osteonic canal, connecting lacunae

15. Haversian System: (aka Osteon) the whole system of concentric circles and the canals associated with them

16. Volkmann’s canals, contain larger vessels and nerves allowing for communication of entire Haversian systems, the medullary canal, and the bone surface.

17. Spongy bone avoids this whole process, thin bony plates allow for nourishment by diffusion.

18. Development Should it be a choice?
This is what a baby looks like toward the end of the FIRST trimester, the time of most reported abortions. While the majority of bone formation happens between weeks, much of the structure is visible within the first 4 wks. Facial structure appears within the FIRST WEEK of pregnancy. This little person has a face, before you even know it exists!

19. Two means of bone formation:
Intramembranous bone formation
Endochondral bone formation

20. Intramembranous Bone Broad, flat bones of the skull Formation
Osteoblasts become active and spongy bone is formed throughout existing membrane.
Left over membrane becomes periosteum.

21. Endochondral Bone Most long bones Formation:
Masses of hyaline cartilage develop rapidly giving even the young fetus a “human” structure.

22. Ossification is a gradual process
The center of the medullary cavity serves as the primary ossification center.
Ossification occurs from the inside out.

23. The secondary ossification center is formed later in the open space of the epiphysis.
This ossification also occurs in an outward direction.

24. Between the two ossification centers there is an epiphyseal disc (AKA growth plate)

25. Bone formation, lengthening continues until the two ossified areas meet.

26. Bone Demolition
Osteoclasts break down bone tissue

27. Remodeling
Osteoblasts form new bone tissue for replacement and remodeling.

28. Gross Function Provide shape Support Protection Provide structure
Serve as storage units
Aid in body movement
Blood cell formation

29. Movement
Gross movement

30. 4 Parts of a Lever Rod (bar) Fulcrum (pivot)
Resistance ( weight being moved.
Force (energy supplying movement)

31. Example Rod: radius and ulna Fulcrum: elbow joint
Resistance: hand and object
Force: biceps brachii

32. Resistance: hand and object Force: triceps brachii
What is the reverse?
Rod: radius and ulna
Fulcrum: elbow joint
Resistance: hand and object
Force: triceps brachii

33. What is happening? c. e. d. a. b.

34. Blood Cell Formation
Hematopoiesis

35. Once upon a time…
in the yolk sac hematopoiesis began for the embryo. Throughout life hematopoiesis continues in the …

36. Liver
Spleen
Bone marrow
Red marrow
(Yellow marrow)

37. Red Marrow
Functions in the formation of:
RBC
WBC
platelets

38. Why is it red?
Hemoglobin carried in RBC, changes the pigmentation of the marrow.

39. Yellow Marrow Functions in fat storage. Inactive in hematopoiesis.
Replaces much of the red marrow as a human ages.

40. Why is it yellow?
Fat in the body is yellow. Gooey, gross, and yellow.

41. Oh where oh where did the red marrow go?
While most of the red marrow is replaced by yellow marrow, red marrow for hematopoiesis does remain in the spongy bone of the…

42. Thorax
Vertebra
Pelvis
Epiphysis of the
Humerus
Femur

43. Bone as a Storage Unit
Bone is used to store inorganic salts. (No Carbon)
Primarily stores Ca+
[Ca+] control
If [Ca+] in blood is too low

44. osteoclasts are stimulated to breakdown bone tissue to release Ca+.
If [Ca+] in blood is too high, osteoblasts are stimulated to form bone tissue, trapping the Ca+.

45. CUT

46. Organization 2 major portions Axial: head, neck, and trunk
Appendicular: limbs and anchoring parts

47. Axial Skull: cranium and facial bones
Hyoid bone: between jaw and neck, helps tongue function

48. Vertebral column: back bone, series of bony vertebrae and cartilaginous intervertebral discs.

49. Thoracic cage: used to protect the organs of the thorax and upper abdomen.

50. Appendicular
Pectoral girdle: clavicle and scapula, the attachment site of the arm.
Upper limb: humerus, radius, ulna, carpals, metacarpals, phalanges.

51. Pelvic girdle: 2 coxal bones forming protection for lower organs and attachment site for legs.
Lower limbs: femur, tibia, fibula, patella, tarsals, metatarsals, phalanges.

52. Skull Cranium 8 interlocked bones
Points of attachment for these interlocked bones are visible sutures
many of the cranial bones have sinuses, air filled spaces

53. Cranium
Frontal
Parietal
Occipital
Temporal
Sphenoid

54. Facial Jaw Maxilla Palatine Zygomatic lacrimal Ethmoid Nasal Vomer
Nasal conchae
Mandible
(Processes)