1. Skeletal System Lecture
Day 2: Joints, Fractures, and the Healing Process

2. Joints hold bones together, giving stability,
yet at the same time, give our skeleton mobility.
There are three types of joints:
Fibrous
Cartilaginous
Synovial

3. Fibrous: bones connected by fibrous tissue (no movement)
Bones of skull
Pelvic bones
Examples of Fibrous joints

4. Cartilaginous: bones connected by cartilage (slightly movable)
Examples of Cartilaginous joints

5. Synovial: articulating bone ends are separated by a joint cavity and inside is synovial fluid (allows for more movement) Synovial joints are found in all limbs and allow for various movements.
Examples of Synovial joints

6. There are 6 main types of synovial joints:
Plane/gliding joints
Hinge joints
Pivot/rotating joints
Condyloid joints
Saddle joints
Ball and socket joints

7. Plane or Gliding Wide range of mostly sideways, gliding movement
Examples:
Wrist
Ankles
Spine

8. Hinge Joint Unaxial movement in one direction (like a door)
Flexion/Extension
Examples:
Knee
Elbow

9. Pivot/Rotating Joints
Rotation around an axis
Rotation of one bone around another
Example:
Radioulnar joint (in the forearm)
Top of neck

10. Condyloid Joint Some sideways movements but no rotation Examples:
Metacarpals (hand)
Carpals (fingers)
Jaw

11. Saddle Joints
This type of joint allows for back and forth and side to side motion but limited rotation.
Examples:
In the thumb

12. Ball and Socket Joint Uniaxial movements & full rotation Examples: Hip
Shoulder

13. Bone Fractures & Healing

14. Although bones are strong, they are susceptible to breaks (fractures) all throughout life.
The most common times in life for fractures to occur are during youth (due to excessive activity, sports, and bad judgement) and in the elderly (due to bone thinning and weakening, often due to osteoporosis).

15. Six most common types of fractures:
Comminuted
Compression
Depressed
Impacted
Spiral
Greenstick

16. Comminuted fractures:
Bone breaks in many fragments.
Common to sporting accidents

17. Vertebrae become crushed. Common during falls
Compression fractures:
Vertebrae become crushed.
Common during falls

18. Depressed fractures: Skull bone is pressed inward, causing a fracture
Common to blunt force trauma

19. Broken bone ends are forced into each other.
Impacted fractures:
Broken bone ends are forced into each other.

20. Spiral fractures:
Ragged break occurs during twisting.

21. Greenstick fractures:
Bone breaks incompletely (like a young twig).

22. The process of fracture/bone healing:
A hematoma is formed. Blood vessels are ruptured when bone breaks. As a result, a blood-filled swelling forms. Bone cells are deprived of nutrition and die.
hematoma (swelling)

23. Connective tissue cells of various types form a mass of
2) The break is splinted by a fibrocartilage callus.
Connective tissue cells of various types form a mass of
repair tissue called fibrocartilage callus
(containing cartilage matrix, bony matrix, and collagen fibers)
which act to “splint” the broken bone, closing the gap.

24. 3) A bony callus is formed. Osteoblasts and osteoclasts migrate to
the area and multiply. Thus the fibrocartilage callus is gradually
replaced by one made of spongy bone, known as the bony callus.

25. 4) Lastly, bone remodeling occurs. Over the next few weeks
to months, the bony callus is remodeled in response to mechanical
stresses placed on it, so that it forms a strong permanent (bone) patch at the fracture site.

26. The end!