1. The Skeletal System
Bones and Joints

2. Functions Supports and give shape to the body Protects internal organs
Helps make movements possible when bones at moveable joints are pulled by muscles
Stores calcium – hormones regulate calcium storage:
calcitonin (CT) increases storage
parathyroid hormone (PTH) reduces store of calcium
Hematopoiesis – blood cell formation in red bone marrow

3. Classified according to overall shape
Types of Bones
Classified according to overall shape
Long Short
humerus carpals
Flat Irregular
frontal vertebrae
Sesamoid (round) bone
patella

4. Structure of Long Bones
Diaphysis – shaft – hollow tube of hard compact bone Medullary cavity – hollow area inside diaphysis, contains yellow bone marrow Epiphyses – ends – spongy bone that contains red bone marrow Articular cartilage – covers epiphyses and functions as cushion Periosteum – strong membrane covering bone everywhere except joint surfaces Endosteum – thin membrane lining medullary cavity

5. Structure of Flat Bones
Spongy bone layer sandwiched between two compact bone layers
Diploe – spongy bone layer of a flat bone

6. Quick Check Name some of the organs of the skeletal system.
What are the five major functions of the skeletal system?
What are the four categories of bone in the skeletal system?
Describe the major features of a long bone.
How does the typical flat bone differ?

7. Cancellous Bone Spongy (cancellous) bone
Texture results from needlelike threads of bone called
trabeculae surrounded by open spaces
Found in epiphyses of bones
Spaces contain red bone
marrow

8. Compact Bone Hard, dense and appears solid to the naked eye
Structural unit is an osteon
calcified matrix arranges in
layers of rings called
concentric lamella
Bone cells are called osteocytes
Found between hard layers of the lamellae in little spaces called lacuanae
Are connected by tiny tubes called canaliculi

9. Cartilage Cell is called a chrondocyte Has the flexibility of plastic
Matrix is gel-like
Lacks blood vessels so
healing is slow after
an injury

10. Bone Formation and Growth
Long bone grows from small centers located in both ends (epiphyses) and from the large center (diaphysis)
Epiphyseal plate – cartilage that indicates a bone is still growing in size
Epiphyseal line – remains to mark
the location where the two centers
of ossification have fused together

11. Quick Check
What is the basic structural unit of compact bone tissue called?
What are osteocytes?
Where would you find them in bone tissue?
What is ossification?
What is the role of the osteoblast?

12. Divisions of the Skeleton
Axial
Appendicular
Skull
Spine (vertebral column)
Thorax
Hyoid bone
Upper extremities, including shoulder (pectoral) girdle
Lower extremities, including hip (pelvic) girdle

13. Skeletal Differences Female Male Pelvis – shallow and broad
Wider pelvic inlet to allow for childbirth
Wider pubic angle
Generally larger
Pelvis -deep and narrow

14. Types of Joints Synarthroses Amphiarthroses
No movement – fibrous connective tissue grows between bones
Slight movement – cartilage connects articulation bones

15. Types of Joints Diarthroses – permit free movement
Joint capsule and ligaments hold adjoining bones together but permit movement
Articular cartilage cover joint ends
of bones where they form joints
with other bones
Synovial membrane – lines joint
capsule and secretes lubricating fluid
Joint cavity – space between joint
ends of bones
Bursa – fluid-filled pouch that
absorbs shock

16. Types of Diarthrotic Joints
Ball and Socket
Hinge
A ball shaped head of one bone fits into a concave socket of another
Widest range of movement
Movement in 2 directions
Flexion and extension
Elbow
Knee
Fingers

17. Types of Diarthrotic Joints
Pivot
Saddle
A small projection from one bone pivots in an arch of another
Rotation
Atlas and axis (1st and 2nd vertebrae)
Permit great mobility
Flexion, extension, abduction, adduction, circumduction
Only between metacarpal of thumb and carpal bone of wrist

18. Types of Diarthrotic Joints
Gliding
Condyloid
A condyle, or oval projection fits into an elliptical socket
Least movable diarthrotic joint
Flat, articulating surfaces permit limited gliding movement

19. Types of Movement Flexion Extension Reduces the angle of the joint
Ex. Bending the elbow
Increases the angle of a joint
Ex. Straightening a bent elbow

20. Types of Movement Rotation Circumduction
Spins one bone relative to another
Ex. Rotating the head at the neck joint
Moves the distal end of a bone in a circle while keeping the proximal end relatively stable
Ex. Circumducting the shoulder joint

21. Types of Movement Abduction Adduction Moving away from the midline
Ex. Moving the arm to the side away from the body
Moving toward the midline
Ex. Moving the arm towards the body

22. Quick Check
What are the 3 major types of joints in the skeleton? Give an example of each.
What membrane in a diarthrotic joint provides lubrication for movement?
What is a ligament?
List and describe the 6 types of movement and give an example of each.