1. Joints
Vertebrate Anatomy
Ch. 8

2. Joints = Articulation Where 2 or more bones meet Function
Mobility
Protection (sutures in the skull)
Weakest parts of the skeleton
But, structure of joints does resist various forces to some degree

3. Classification Structural and Functional Classifications
Fibrous - immovable
Cartilaginous – slightly moveable
Synovial – freely moveable

4. Fibrous Joints Sutures Bones connected by fibrous sheet – ligament
Example: ligament connecting tibia to fibula; radius to ulna
Tooth
Peg in socket

5. Cartilaginous Joints Epiphyseal plates Ribs and sternum Symphases
Growing parts at the ends of long bones
temporary
Ribs and sternum
Costal cartilage connects
Flexibility to allow for expansion and compression of rib cage
Symphases
Example: pubic symphasis
Flexibility and strength

6. Synovial Joints Articulating bones are separated by a fluid cavity
Allows for freedom of movement
All joints of limbs are synovial joints

7. Features of Synovial Joints
Articular cartilage
Glassy and smooth
Cover opposing bone surfaces
Absorb compression; prevent crushing

8. Features of Synovial Joint
Joint Cavity
Filled with fluid
Synovial fluid characteristics
Slippery
Occupies all free spaces
Reduces friction

9. Features of Synovial Joint
Articular Capsule
Encloses the joint cavity
Composed of membranes

10. Features of Synovial Joint
Reinforcing ligaments
Connect bone to bone
The more ligaments, the stronger the joint
Stretching of the ligaments results in a weaker joint
A ligament can only be stretched about 6% of its length before it snaps.
Muscle tone is the most important factor in stabilizing joints

11. Knee Ligaments

12. Features of Synovial Joint
Fatty pads
Meniscus
Disc of fibrocartilage
Separates articular surfaces of bones; improves fit between articulating bone ends
Example – knee

13. Bursae and Tendon Structures and the Synovial Joint
Tendons and bursae are not strictly considered parts of synovial joints, but are closely associated with them
Tendon
Cartilaginous
Attaches muscle to bone
Tendon sheath wraps around the tendon and protects from friction
Bursae
Bags of fluid lying between tendons and joints
Act like ball bearings
Reduce friction as tendon passes over joint

14. Movements of Synovial Joints
Gliding
Between carpals, tarsals and vertebrae
Angular
Flex
Extend
Abduct
adduct
Rotation

15. Types of Synovial Joints
Gliding
Between carpals/tarsals
Hinge
elbow
Pivot
Atlas/axis
Ball and socket
Hip
Saddle
Thumb
Condyloid
Knuckles

16. Gliding joint

17. Hinge joint

18. Condyloid joint

19. Saddle joint

20. Ball and Socket joint

21. Pivot joint

22. Injuries

23. Injuries Sprain Ligaments are stretched or torn
Sprains heal slowly (cartilagenous tissue poorly vascularized)
Completely ruptured ligaments must be repaired surgically
Inflammation in the joint can turn ligament to “mush”
Some cannot be repaired – use of tendons to replace ligaments – staple onto bone

24. Injuries Cartilage injury
Damaged cartilage can be removed by arthroscopic surgery – meniscus damage is commonly treated with this method

25. Injuries
Dislocation
Bones are forced out of normal positions at a joint
Repeats of this injury are common due to stretching of ligaments in the initial injury

26. Injuries Inflammation and Degenerative conditions Arthritis –
may be degenerative (osteoarthritis – wear and tear) or
inflammatory (rheumatoid arthritis – auto immune disorder)

27. Injuries
Bursitis and Tendonitis - inflammation

28. Bone Spurs
Result when body tries to repair itself by building extra bone
Forms in response to pressure; rubbing, etc. over a prolonged period
Also forms due to aging
Cartilage at joints breaks down
Bone rubs against bone
Osteoarthritis can lead to bone spurs

29. Other joint problems Craniosynostosis
Sutures in an infant close too early
Can cause problems with brain and skull growth
Can be corrected with surgery
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