1. Skeletal System

2. There are five functions of bones
1. support
2. protection
3. movement
4. mineral reservoir
5. hemopoiesis (blood cell formation)

3. Common bone part names
1. Depressions & openings
Fossa: hollow or depression
Sinus: cavity
Foramen: a hole
meatus: tube shaped opening

4. 2. Projections & Processes
condyle: a rounded projection
head: a rounded projection beyond a narrow neck-like portion
trochanter: very large projection
crest: a ridge
spinous process: a sharp projection
tuberosity: a large, rounded projection

5. Tubercle: a small, rounded projection
diaphysis: shaft of a bone
epiphysis: broad end of a bone

6. The skeletal system has two major divisions
1. Axial skeleton: 80 bones, 74 in upright axis and 6 tiny middle ear bones
2. Appendicular skeleton: 126 bones
Thus the body has 206 bones plus some “sesamoid bones” so named due to their resemblance to sesame seeds, often found in various tendons.

7. The skull has 28 irregularly shaped bones with 2 divisions
1. cranium: “brain case”, which has 8 bones and all cranial bones are unpaired except the parietal & temporal
2. Face: all face bones are paired
except the mandible & vomer

8. Bones come in four common shapes
1. long bones (humerus, ulna)
2. short bones (tarsals)
3. flat bones (frontal, parietal)
4. irregular bones (vertebrae)

9. There are four major microscopic structures of bone
1. lamellae: cylinder shaped layers of calcified matrix

10. 2. Lacunae: small spaces containing
2. Lacunae: small spaces containing tissue fluid in which bone cells lie
3. Canaliculi: ultrasmall canals radiating out from the lacunae connecting them

11. 4. Haversian canals: contains blood. vessels and lymphatic vessels
4. Haversian canals: contains blood vessels and lymphatic vessels. Moves fluid through and brings nutrients and oxygen to the cells

12. Skeletal Articulations
Articulations (joints) serve two functions
1. hold bones firmly to each other
2. permit movement

13. There are three types of joints, grouped based according to degree of movement
1. synarthroses: immovable, found
in skull sutures

14. 2. amphiarthroses: slightly movable,. found between tibia & fibula,
2. amphiarthroses: slightly movable, found between tibia & fibula, between pubic bones, and between adjacent vertebrae

15. 3. diarthroses: movable, found in. elbow, ankle, wrist, shoulder, hip
3. diarthroses: movable, found in elbow, ankle, wrist, shoulder, hip etc.

16. Bone formation
Bone formation begins by three months after fertilization. This “skeleton” is really cartilage structures shaped like bones.

17. Special bone forming cells called osteoblasts form
The Golgi apparatus in an osteoblast specializes in synthesizing and secreting carbohydrate compounds called mucopolysaccharides and the E.R. makes a protein called collagen. The mucopolysaccharides and the collagen form a bone matrix. Calcium salts are then deposited in this matrix creating bones

18. As bone ages cells called osteoclasts enlarge the diameter of the medullary cavity by eating away the bone of its walls.
At the same time osteoblasts from the periosteum build new bone around the outside of the bone.
This bone formation is called ossification and the bone destruction is called resorption. At a young age ossification is faster than resorption but around age 35 – 40 it reverses.

20. The angle inferior to the pubic symphysis
Male vs. Female Skeletons
The angle inferior to the pubic symphysis
in males is < 90 degrees. In females the
angle is > 90 degrees
The male coccyx points anteriorly while in
females it points inferiorly
The pelvic inlet in males is heart shaped
while in females it is oval
- The bones of a male skeleton are larger

21. SKELETAL DISORDERS & DISEASES
Myositis ossificans: the deposition of bone around skeletal muscle. A muscle injury can trigger a minor case, there is no known cause of a severe case.

22. normal scoliosis Abnormal curvatures of the spine
About 3% of the population has an abnormal curvature of their spine

23. Inflammatory (Rheumatoid) arthritis: Starts with
Inflammatory (Rheumatoid) arthritis: Starts with inflammation of the synovial tissue and moves to the cartilages. Joint replacement may be needed in severe cases.

24. In 1985, on Monday Night Football, Joe Theismann of the Washington Redskins suffers a compound break of his tibia and it sticks into the dirt of the field.

25. Bone Breaks Simple – remains internal
Compound – breaks through the skin

26. Displaced – produces new arrangements
Non-displaced – retains normal alignment

27. Colles’ – break in distal portion of radius

28. Pott’s – breaks both the tibia & fibula

29. Greenstick – one or both sides of the bone is
Greenstick – one or both sides of the bone is broken and the other side bends, only seen in children

30. Transverse – a fracture at right angles to the long axis

31. Comminuted – bone is splintered and small. fragments are found
Comminuted – bone is splintered and small fragments are found between the two main parts

32. Spiral break: bone is twisted apart

33. Impacted: one bone is driven into another

34. Arthritis: involves damage to the articular
Arthritis: involves damage to the articular cartilages due to infections, injury, metabolic problems and severe physical stresses.
Arthritis can be either degenerative which starts in the cartilages and moves to the underlying bones with inflammation occurring.