1. Chapter 5: The Skeleton Joints and Developmental Aspects of the Skeleton

2. Joints AKA “Articulations” of bones Sites where two or more bones meet Functions of joints: Hold bones together Allow for mobility Ways joints are classified: Functionally Structurally

3. Functional Classification of Joints Based on amount of movement the joint allows Synarthroses Immovable joints Found in axial skeleton for firm attachments & protection Amphiarthroses Slightly moveable joints Found in axial skeleton for firm attachments & protection Diarthroses Freely moveable joints Found in limbs where mobility is important

4. Structural Classification of Joints Based on whether fibrous tissue, cartilage, or joint cavity separates bony regions at joint Fibrous joints Generally immovable Cartilaginous joints Immovable or slightly moveable (mostly amphiarthrotic) Synovial joints Freely moveable

5. Summary of Joint Classes [Insert Table 5.3 here] Table 5.3

6. Fibrous Joints Bones united by fibrous tissue Examples : Sutures of the skull Syndesmoses Allows more movement than sutures because fibers are longer Example : Distal end of tibia and fibula

7. Fibrous Joints Figure 5.28a–b

8. Cartilaginous Joints Bones connected by cartilage Examples : Pubic symphysis of pelvis (where pubic bones meet) Intervertebral joints of spinal column Articulating bone surfaces are connected by pads of fibrocartilage Hyaline cartilage epiphyseal plates of growing long bones & cartilaginous joints between ribs & sternum Immovable (synarthrotic) joints

9. Cartilaginous Joints Figure 5.28c–e

10. Synovial Joints Articulating bones are separated by a joint cavity Synovial fluid is found in the joint cavity All limb joints are synovial joints Examples: Shoulder joint Elbow joint Intercarpal joints of hands

11. Synovial Joints Figure 5.28f–h

12. Features of Synovial Joints Articular cartilage (hyaline cartilage) covers the ends of bones A fibrous articular capsule encloses joint surfaces & is lined with a synovial membrane A joint cavity is filled with synovial fluid Ligaments reinforce the joint

13. Structures Associated with the Synovial Joint Bursae—flattened fibrous sacs Lined with synovial membranes Filled with synovial fluid Not actually part of the joint Tendon sheath Elongated bursa that wraps around a tendon Both bursa & tendon sheaths function to reduce friction between adjacent structures during joint activity

14. The Synovial Joint Figure 5.29

15. Types of Synovial Joints Based on Shape PLANE JOINT Surfaces are flat so gliding motion Example = intercarpal joints of wrist HINGE JOINT Cylinder fits into trough Examples = elbow joint, ankle joint, & phalange joints of fingers PIVOT JOINT Rounded end fits into ring of bone Examples = radioulnar joint & atlas/axis joint

16. Types of Synovial Joints Figure 5.30a–c

17. Types of Synovial Joints Continued... CONDYLOID JOINT Egg-shaped surface fits into oval cave Side-to-side & back-&-forth motion Example = knuckle (metacarpophalangeal joints) SADDLE JOINT Each surface has convex & concave area Example = carpometacarpal joints of thumb BALL-AND-SOCKET JOINT Head of one bone fits into socket of another Examples = shoulder & hip joints

18. Types of Synovial Joints Figure 5.30d–f

19. Inflammatory Conditions Associated with Joints Bursitis—inflammation of a bursa usually caused by a blow or friction (“water on the knee”) Sprain – ligaments or tendons reinforcing joint are damaged by excessive stretching or torn away from bone; heal slowly & are painful Tendonitis—inflammation of tendon sheaths Arthritis—inflammatory or degenerative diseases of joints (“Arth” = joint, “ritis” = inflammation) Over 100 different types The most widespread crippling disease in the United States

20. Clinical Forms of Arthritis Osteoarthritis Most common chronic arthritis “Wear & tear” arthritis Probably related to normal aging processes Rheumatoid arthritis An autoimmune disease—the immune system attacks the joints Symptoms begin with bilateral inflammation of certain joints Often leads to deformities

21. Clinical Forms of Arthritis Gouty arthritis Inflammation of joints is caused by a deposition of uric acid crystals from the blood Can usually be controlled with diet

22. Developmental Aspects of the Skeletal System Fetus: Fetal long bones are made of hyaline cartilage. Birth: Cartilage has mostly been converted to bone. Skull bones are incomplete. Bones are joined by fibrous membranes called fontanels Fontanels are completely replaced with bone by two years after birth

23. Ossification Centers in a 12-week-old Fetus Figure 5.32 Red areas indicate ossification centers. Lighter regions are still fibrous or cartilaginous.

24. Skeletal Changes Throughout Life End of Adolescence Epiphyseal plates become ossified and long bone growth ends Size of cranium in relationship to body 2 years old—skull is larger in proportion to the body compared to that of an adult 8 or 9 years old—skull is near adult size and proportion Between ages 6 and 11, the face grows out from the skull

25. Skeletal Changes Throughout Life Figure 5.33a

26. Skeletal Changes Throughout Life Figure 5.33b Arms & legs grow faster than head & trunk

27. Skeletal Changes Throughout Life Curvatures of the spine Primary curvatures (thoracic & sacral) are present at birth and are convex posteriorly Secondary curvatures (cervical & lumbar) are associated with a child’s later development and are convex anteriorly Abnormal spinal curvatures (scoliosis and lordosis) are often congenital

28. Skeletal Changes Throughout Life Figure 5.16

29. Skeletal Changes Throughout Life Osteoporosis Bone-thinning disease afflicting 50% of women over age 65 20% of men over age 70 Disease makes bones fragile and bones can easily fracture Vertebral collapse results in kyphosis (also known as dowager’s hump) Estrogen aids in health and normal density of a female skeleton

30. Skeletal Changes Throughout Life Figure 5.34 Osteoporotic Bone Normal Bone

31. Skeletal Changes Throughout Life Figure 5.35