1. Skeletal System - Part I
Bone Structure
Skeletal System - Part I

2. Introduction
Skeletal System - the entire framework of bones (206) and their cartilage, tendons & ligaments
They study of bone disorders is called osteology.
Orthopedics - the branch of medicine that deals with the preservation and restoration of the skeletal system and its associated structures
Bones are active living tissue and therefore the organs of the skeletal system

3. Skeletal Functions Support Protection Assisting in movement
Mineral homeostasis
Production of blood cells
Triglyceride storage

4. Bone Composition
Composed of the mineral salts calcium carbonate & calcium phosphate which make up 67% of bone materials
Collagen (33%) is the major protein (90%) that provides a soft framework
Calcium phosphate is a mineral that adds strength and hardens the framework
Small amounts of fluoride, magnesium hydroxide and sulfate
Together these minerals compose crystal mineral salts called Hydroxyapatite

5. Types of Bones

6. Long Bones Greater length than width
Have a distinct diaphysis and a variable number of epiphysis
Slightly curved for strength
Femur, humerus, ulna, radius, tibia, fibula, metacarpals, metatarsals, phalanges

7. Short Bones some what cubed shaped bones
nearly equal in length and width
spongy texture on inside of the bone
Carpal (wrist) and tarsal (ankle) bones

8. Flat Bones generally thin and flat
compact bone on anterior and posterior surfaces with spongy bone in the middle
provides protection to organs
great surface area for muscle attachment
cranial bones, sternum, scapula, ribs

9. Irregular Bones complex shaped bones
can’t be classified into other categories
vary in the amount of spongy and compact bone
vertebrae, facial bones

10. Sesamoid (Round) Bones
small bones situated in tendons where considerable pressure develops
vary in number between individuals
kneecaps

11. Figure 7.1 - Bone Classification

12. Long Bone Structure Diaphysis Epiphyses (2) Metaphyses (2)`
Articular Cartilage
Periosteum
Medullary cavity
Endosteum
Epiphyseal Disk

13. Long Bone Structure

14. Epiphysis
The Epiphysis is the expanding portion found at the ends of a long bone.
Distal/proximal ends of bone
Articulating surfaces covered with hyaline cartilage
articulates = forms joint w/ another bone
composed mostly of spongy bone

15. Epiphysis d
Epiphysis

16. Epiphyseal Plates
Epiphyseal Plates are cartilaginous layers within the long bone epiphysis that grow.
If an epiphyseal plate is damaged before it ossifies, elongation of the long bone may cease prematurely, pr growth may be uneven.

17. Epiphyseal Plate
Epiphysis
Epiphyseal Plate d
Epiphysis

18. Articulating Cartilage
Articulating Cartilage is a form of hyaline cartilage.
It is found on the articulating portion of the epiphysis.

19. Articulating Cartilage
Epiphyseal Plate
Epiphysis
Epiphyseal Plate d
Epiphysis
Articulating Cartilage

20. Diaphysis The Diaphysis is the longest portion of the bone.
It is the shaft that is located in between the epiphysis found on either end of the long bone.

21. Articulating Cartilage
Epiphyseal Plate
Epiphysis
Diaphysis
Epiphyseal Plate d
Epiphysis
Articulating Cartilage

22. Periosteum
A Periosteum is a tough, vascular covering of fibrous tissue that completely encloses the bone.
It is firmly attached to the bone, and periosteal fibers are continuous with ligaments and tendons that connect to the membrane.
Also helps form and repair bone tissue.

23. Articulating Cartilage
Epiphyseal Plate
Epiphysis
Diaphysis
Periosteum
Epiphyseal Plate d
Epiphysis
Articulating Cartilage

24. Compact Bone (Cortical)
The wall of the diaphysis is mainly composed of tightly packed tissue called Compact Bone.
This tissue has a continuous matrix with no gaps.
Outer layer of bone

25. Articulating Cartilage Epiphyseal Plate Epiphysis
Compact
Bone
Diaphysis
Periosteum
Epiphyseal Plate d
Epiphysis
Articulating Cartilage

26. Spongy Bone (trabecular)
The epiphyses are composed largely of Spongy Bone with thin layers of compact bone on their surfaces.
Inner layer of bone
Consists of numerous branching bony plates called trabeculae.
Irregular connecting spaces between these plates helps reduce the bone’s weight and are filled with red marrow.
Both compact and spongy bone are strong and resist bending.

27. Articulating Cartilage Epiphyseal Plate Epiphysis
Spongy Bone
Compact
Bone
Diaphysis
Periosteum
Epiphyseal Plate d
Epiphysis
Articulating Cartilage

28. More Structures…
Compact bone in the diaphysis forms a semi-rigid tube with a hollow chamber called the Medullary Cavity.
A thin layer of cells called Endosteum lines these areas.
A specialized type of soft connective tissue called Marrow fills these regions.

29. Articulating Cartilage Epiphyseal Plate Epiphysis
Spongy Bone
Space Containing Red Marrow
Medullary Cavity
Endosteum
Compact
Bone
Yellow Marrow
Diaphysis
Periosteum
Medullary Cavity
Epiphyseal Plate d
Epiphysis
Articulating Cartilage

30. Types of Bone Cells
Osteoblasts - Bone building cells; synthesize and serete collagen fibers to build matrix of bone
Osteocytes - Mature bone cells; maintain bone tissue and metabolism
Osteoclasts - Large cells formed from white blood cells; break down bone tissue

31. Microscopic Structure
Recall that bone cells called Osteocytes are in tiny, bone chambers called Lacunae.
Lacunae, which form concentric circles around Central Canals or Haversian canals.
Osteocytes communicate with nearby cells by means of cellular processes passing through Caniliculi.
Caniliculi are cytoplasmic processes that extend outward and pass though very small tubes in the boney matrix.

33. More on Compact Bone Sheets of bone create Lamellae
Lamellae are concentrically clustered around a central canal and form cylinder-shaped units called Osteons or Haversian Systems.
It is many of these units fused together that form the substance of compact bone.

35. Vascularity
Each central canal contains blood vessels and nerve fibers.
These structures are surrounded by loose connective tissue.
Blood in these vessels nourishes osteocytes associated with the central canal.

36. Central Canals Continued
Central canals extend longitudinally through bone tissue.
Transverse canals called Perforating Canals connect the central canals to one another.
Perforating canals contain larger blood vessels and verves that allow the communication to take place between the central canals both near the surface and in the medullary cavity.

38. One Last Thing About Spongy Bone
Spongy bone is also composed of osteocytes and intracellular material.
This type of bone tissue does not aggregate around central canals and relies of diffusion to move nutrients into the cells.
Substances diffusing into the canaliculi that lead to the surface of these thin, boney plates and nourish the cells.

39. Sickle Cell Anemia Recessive genetic disorder
Causes sickle-shaped red blood cells.
These sickle cells obstruct circulation
Severe bone pain is one symptom of the disease
Radiographs can reveal blocked arterial blood flow in bones of these patients

40. Sicle Cell and Stem Cells