The skeletal system is divided into two sections - the axial skeleton which includes the skull, vertebral column, and rib cage, and the appendicular skeleton which includes the limbs and girdles attaching them to the axial skeleton. Bones provide structure, protection, movement, mineral storage, and blood cell formation. There are 206 bones in the human body which come in four shapes - long, short, flat, and irregular. Bones are made of two types of tissue and contain three main cell types. Joints connect and allow movement between bones. The main types of joints are fibrous, cartilaginous, and synovial, with synovial joints providing the most movement.

2. Parts of the skeletal system:
• Bones (skeleton)
• Joints
• Cartilages
• Ligaments (bone to bone)(tendon=bone to
muscle)
Divided into two sections
• Axial skeleton- skull, spinal column, and rib
cage
• Appendicular skeleton – limbs and girdle
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3. Functions of Bones
• Support of the body
• Protection of soft organs
• Movement due to attached skeletal
muscles
• Storage of minerals and fats
• Blood cell formation
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4. Bones of the Human Body
• The skeleton has 206 bones
• Two basic types of bone tissue
• Compact bone
• Homogeneous
• Spongy bone
• Small needle-like
pieces of bone
• Many open spaces
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Figure 5.2b

5. Bones are classified by their
shape:
1.Long- bones are longer than
they are wide (arms, legs)
2.Short- usually square in
shape, cube like (wrist, ankle)
3.Flat- flat , curved (skull,
Sternum)
4.Irregular- odd shapes
(vertebrae, pelvis)

6. Classification of Bones on the
Basis of Shape
Figure 5.1
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7. Types of Bone Cells
• Osteocytes
• Mature bone cells
• Osteoblasts
• Bone-forming cells
• Osteoclasts
• Bone-destroying cells
• Break down bone matrix for remodeling and
release of calcium
• Bone remodeling is a process by both
osteoblasts and osteoclasts
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8. Changes in the Human Skeleton
• In embryos, the skeleton is primarily
hyaline cartilage
• During development, much of this cartilage
is replaced by bone
• Cartilage remains in isolated areas
• Bridge of the nose
• Parts of ribs
• Joints
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9. The Human
Skeleton

10. Appendicular
skeleton
Axial
Skeleton

11. The Axial Skeleton
• Forms the longitudinal part of the body
• Divided into three parts
• Skull
• Vertebral Column
• Rib Cage
• Supports and protects organs of
head, neck and trunk.
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13. The Axial Skeleton
Figure 5.6
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Slide

14. Appendicular skeleton includes
bones of limbs and bones that
anchor them to the axial skeleton.
Appendicular skeleton:
pectoral girdle (clavicle, scapula)
upper limbs (arms)
pelvic girdle (sacrum, coccyx)
lower limbs (legs)
Articulation- where joints meet,
connect, and are formed.

15. Joints
A joint, or articulation, is the place where
two bones come together.
• Fibrous- Immovable:connect bones, no
movement. (skull and pelvis).
• Cartilaginous- slightly movable, bones are
attached by cartilage, a little movement
(spine or ribs).
• Synovial- freely movable, much more
movement than cartilaginous joints. Cavities
between bones are filled with synovial fluid.
This fluid helps lubricate and protect the
bones.

16. The Synovial Joint
Figure 5.28
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Slide 5.51

17. Types of Synovial Joints Based on
Shape
Figure 5.29a–c
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Slide

18. Types of Joints based
on Movement
Hinge- A hinge joint allows extension and
retraction of an appendage. (Elbow,
Knee)

19. Ball and Socket- A ball and socket joint
allows for radial movement in almost
any direction. They are found in the
hips and shoulders. (Hip, Shoulder)

20. Gliding- In a gliding or plane joint bones
slide past each other. Mid-carpal and midtarsal joints are gliding joints. (Hands,
Feet)

21. Saddle- This type of joint occurs when the
touching surfaces of two bones have both
concave and convex regions with the
shapes of the two bones complementing
one other and allowing a wide range of
movement. (Thumb)