1. Bones, Skeleton, & Joints
The Skeletal System
Bones, Skeleton, & Joints

2. Unit Objectives
Identify the subdivisions of the skeleton as axial or appendicular
Axial
On a skull or diagram, identify & name the bones of the skull
Describe how the skull of a newborn infant differs from that of an adult, and explain the function of fontanels
Name the various parts of a typical vertebra
Discuss the importance of the intervertebral discs and spinal curvatures
Explain how the abnormal spinal curvatures (scoliosis, lordosis, and kyphosis) differ from one another
Appendicular
Identify on a skeleton or diagram the bones of the shoulder and pelvic girdles and their attached limbs
Describe important differences between a male and female pelvis
List at least 3 functions of the skeletal system
Name the four main kinds of bones
Identify the major anatomical areas of a long bone
Explain the role of bone salts and the organic matrix in making bone both hard & flexible
Describe briefly the process of bone formation in the fetus and summarize the events of bone remodeling
Name & Describe the various types of fractures
Name the 3 major categories of joints and compare the amount of movement allowed by each
Understand the functions and differences between tendons & ligaments
Identify some of the causes of bone and joint problems throughout life

3. Functions of Bone Support & Give shape to the body
Protects Internal Organs
Helps make movements possible
Stores calcium
Hemopoiesis or blood cell formation

4. Types of Bones
Long
Short
Flat
Irregular

5. Structure of Long Bones
Diaphysis or shaft
Medullary cavity containing yellow marrow
Epiphyses or ends of the bone; spongy bone contains red bone marrow
Articular cartilage-covers epiphyses as a cushion
Periosteum-strong membrane covering bone except at joint surfaces
Endostuem-lines the medullary cavity

7. Microscopic Structure of Bone and Cartilage
Bone types
Spongy
Texture results from needlelike threads of bone called trabeculae surrounded by a network of open spaces
Found in epiphyses of bones
Spaces contain red bone marrow
Compact
Structural unit is Haversian system-composed of concentric lamella, lacunae containing osteocytes, and canaliculi, all covered by periosteum

8. Osteocyte in lacuna
Lamella
Haversian System

9. Microscopic Structure of Bone and Cartilage con’t
Cell type called chondrocyte
Matrix is gel-like and lacks blood vessels

10. Bone formation & Growth
Sequence of development early-cartilage models replaced by calcified bone matirx
The laying down of calcium salts in the gel-like matrix of the forming bones is an ongoing process
Osteoblasts form new bone, osteoclasts reabsorb bone

11. Development of Bone from Fetus
An infant’s skeleton has many bones that are not yet completely ossified “formed in cartilage”
Fontanels: soft spots on an infant’s skull
Long bone grows from small centers at both ends called epiphyses
As long as cartilage remains in epiphyseal plate body will grow

12. Division of Skeleton
The skeleton is composed of the following divisions & subdivisions
Axial Skeleton
Skull
Spine
Thorax
Hyoid bone
Appendicular Skeleton
Upper Extremities, including shoulder girdle
Lower Extremities, including hip girdle

16. Differences between a Man’s & a Woman’s skeleton
Size: Male skeleton is generally larger
Shape of pelvis: male pelvis is deep and narrow, female pelvis is broad and shallow
Size of pelvic inlet: female pelvis inlet is generally wider, normally large enough for baby’s head to pass through it
Pubic angle: angle between pubic bones of female generally wider

18. Joint (Articulations)
Kinds of joints
Synarthroses (no movement)-fibrous connective tissue grows between articulating bones, for example, sutures of skull
Amphiarthroses (slight movement)-cartilage connects articulating bones; for example symphysis pubis
Diarthroses (free movement)-most joints belong to this class
Structures of freely movable joints-joint capsule and ligaments hold adjoining bones together but permit movement at joint

19. Joints con’t
Articular cartilage-covers joint ends of bones and absorbs joints
Synovial membrane-lines joint capsule and secretes lubricating fluid
Joint cavity-space between joint ends of bones

20. Types of freely movable joints
Ball-and-Socket
Hinge
Pivot
Saddle
Gliding
Condyloid

21. Bone Remodeling & Repair
Remodeling: balance of bone deposit & removal, deposits occur at a greater rate when bone is injured
Controlled by
Hormone used to maintain blood calcium
In response to mechanical stress and gravity, remodels so it is able to withstand the stresses

22. Bone Remodeling & Repair con’t
Fractures are breaks in bones & are classified by:
Comminuted: bone fragments into 3 or more pieces (common with more brittle bones)
Compression: bone is crushed (common with more brittle bones)
Spiral: Ragged break occurs when excessive twisting force is applied to bone (common sports fracture)
Epiphyseal: epiphysis separates from the diaphysis along the epiphyseal plate (common where cartilage is dying)
Depressed: Broken bone portion is pressed inward (common of skull)
Greenstick: bone breaks incompletely (common in children whose bones are more flexible)

24. Bone Remodeling & Repair con’t
Repair 4 stages
Hematoma formation
Fibrocartilaginous callus formation
Bony callus formation
Remodeling of the bony callus

26. Bone & Joint Problems Bone Problems
Osteomalacia: number of disorders in adults in which the bone is inadequately mineralized
Rickets: inadequate mineralization of bones in children caused by insufficient calcium or vitamin D deficiency
Osteoporosis: group of disorders in which the rate of bone reabsorption exceeds the rate of formation

29. Bone & Joint Problems Joint Problems Sprains Dislocations
Bursitis: inflammation of bursa, caused by a blow or friction
Tendonitis: inflammation of the tendons, caused by overuse
Arthritis: inflammatory or degenerative diseases that damage the joints, resulting in pain, stiffness, and swelling of joint

35. Spinal Curvatures
5 major divisions; cervical (7), thoracic (12), lumbar (5), fused of sacrum (5), fused of coccyx (4)
Increase resiliency & flexibility
Cervical & lumbar curvatures are concave posteriorly, and the thoracic & sacral curvatures are convex posteriorly

36. Intervertebral disc
Cushion like pads that act as shock absorbers and allow the spine to flex, extend, and bend laterally

38. Abnormal Spinal Curvatures
Scoliosis: spine is curved from side to side
Lordosis: spine lumbar region is curved inward
Kyphosis: curving of the spine causes a bowing of the back