1. SKELETAL SYSTEM

2. TYPES OF BONES LONG: humerus SHORT: carpals FLAT: frontal bone
IRREGULAR: vertebrae

3. Categorizing bones developmentally…
Endochondral
develop from pieces of cartilage deposited as sheets of tissue in embryo
Face, appendages
Dermal
Formed from sheets of fibrous connective tissue
Clavicle, scapula, flat cranial bones

4. Alveolar Sesamoid Teeth Specialized groupings of bone cells
Form within tendons due to stress on tendon
Patella, pisiform, various metacarpal, metatarsal bones

5. Wormian
Small, irregular, isolated; develop within sutures

6. Bone Structure

7. Periosteum “To surround the bone”
Fibrous membrane, covers surface of the bone EXCEPT at the joint surfaces.
Contains nerves and blood vessels
Nutrition, sensation
This is where the tendons & ligaments attach to the bone.

8. Red marrow
spaces
(surrounded by
trabeculae)
Yellow Marrow

9. Epiphysis At the end of each bone Made of cancellous or spongy bone
Network of bone called trabeculae
Spaces contain red marrow
Site of hematopoiesis (blood cell production)
Outer surface is compact bone
Within joints, surfaces covered with hyaline articular cartilage

10. Epiphysial Plate Also called the “growth plate”;
indicates that additional bone growth is possible
Site of bone elongation
Ossifies over time
then callled epiphysial line

11. Epiphyseal Plate

12. Diaphysis “to grow apart” Hollow Tube
Made of compact bone: organized into osteons
Rigid but light

13. Medullary Cavity Hollow area inside diaphysis Bordered by spongy bone
Lined by a thin membrane called the endosteum
Capable of generating new bone cells
Adults: contains soft, yellow bone marrow
Mostly adipose tissue
Food reserve for bone cells
Children: more red marrow

14. Two kinds of bone Cancellous/Trabecular (Spongy) Compact (cortical)
many spaces filled with marrow
Compact (cortical)
20% of skeleton structure
80% of skeletal weight
Structural unit = osteon

15. The structural unit of bone
The Osteon
The structural unit of bone

16. The OSTEON: Found in compact bone
Matrix is organized into numerous structural units called osteons or Haversian systems.
Consists of calcified matrix arranged in concentric rings called concentric lamellae

17. The Osteon
The rings surround an opening called the Central (Haversian) Canal
Canal contains blood, lymph vessels and nerves

18. The Osteon Mature bone cells = osteocytes
Secrete bone matrix
Composed of collagen fibers and protein (osteocalcin)
The cell resides in a space called a lacuna
Canals, called canaliculi, connect the osteocytes to one another

19. More on the Osteon Nutrients pass
from the blood vessel in the central canal
through the canaliculi
to the osteocytes

20. What can you identify?

22. The Osteon
Central canals are connected by a horizontal blood vessel housed within the Volkmann’s Canals

23. joints

24. Classification: Structural Functional
Tissue composition, structural complexity
Cartilaginous, fibrous, synovial
Functional
Type of movement allowed
Synarthrotic, amphiarthrotic, diarthrotic

25. Bursa – Accessory Structure
Sac-like space made of fibrous tissue
Synovial fluid
thick, lubricating fluid
Nourishes, protects joints and surface
Secreted by epithelial cells
Found in articular areas where rubbing between skin, muscle, ligaments, or bones could occur
Can become inflamed/damaged = bursitis

26. Synarthrotic Joint (Immovable Joints)
Fibrous Joint
Produce NO movement
Bone connected to bone by fibrous tissue
Purpose: to securely hold two bones together
Include
Sutures of the skull (synostoses/sutures)
Skull to teeth (gomphosis)
Tibia and fibula (syndemosis)

27. Amphiarthrotic Joint (Semi-movable)
Cartilaginous
Bone connects to bone via cartilage
Allows slight movement
Includes
Pubic symphisis
Vertebrae

28. Diarthrotic/Synovial Joint
Allows much movement; joint cavity lined by synovial membranes
Types
Ball & Socket: Shoulder, Hip
Hinge: Knee, Shoulder
Pivot: Atlas/Axis
Gliding: Between carpal bones, between tarsal bones
Saddle: thumb
Ellipsoid/Condyloid: wrist

29. BONE development and healing

30. Osteowhat? Osteoblasts secrete a mineralized matrix
The first crystals of bone that
form are pointed and needle-like:
called spicules.
Osteoblasts secrete a mineralized matrix
Once the osteoblast is surrounded by its matrix, it’s called an osteocyte, a bone cell.
Osteoclasts break down bone.

31. Ossification Conversion of embryonic tissues into recognizable bone
2 ways:
Endochondral
Long bones
Intramembranous
Flat bones
Combination – irregular bones

32. Ossification

33. Ossification Mesodermal cells form cartilage centers
Cartilage pegs form
Restructured, filled with hydroxylapatite (calcification)
Pegs formed by fibroblasts
Osteoblasts and osteoclasts sculpt growing bones

34. An osteoclast in action. Here an osteoclasts is eroding bone
An osteoclast in action. Here an osteoclasts is eroding bone. The capsule formed by such action is called a Howship's capsule (H). Similar to the cell of the gut, osteoclasts have a ruffled border which increases the surface area for bone resorption.

35. Direction of Long Bone Growth
Epiphyseal plate made of hyaline cartilage is responsible for long bone growth.
The direction of growth is toward the diaphysis
The newly forming spongy bone (below the growth plate) is not clearly organized as the older spongy bone in the epiphysis above the growth plate.

36. Fontanelles – soft spots
Regions of flat bone not fully ossified
Completed during teenage years

37. healing

38. Fractures Bone is cracked/splintered due to physical injury
Categorized by severity of break/angle at which break occurs

39. Simple: Crack in bone structure May not be readily noticeable
Some large; may involve bleeding, pain, swelling
Greenstick fractures
One side frayed from fracture; other twisted, but not broken

40. Compound/comminuted Open Large fracture
One (more) area is displaced, shattered
Bleeding, swelling
Open
Tearing of skin occurs; easily infected

41. Angle of break Transverse (horizontal) Oblique (angle)
Spiral (twisted)
Angulation – bone changes overall shape
For healing to occur, blood accumulation must occur

42. Healing stages Fracture Granulation Callus Lamellar bone
Normal contour