The Skeletal System

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The Skeletal System

• NO BONES ABOUT IT!

Did you know? The adult skeleton has 206 bones
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Things to Know

• Oste bone
• Art joint
• -blast germ or embryonic
• -clast broken
• -cyte cell
• Peri- around
• Dia- between or across
• Epi- upon
• Hemat- blood

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The Skeletal System

• Parts of the skeletal system
• Bones (skeleton)
• Joints (flexibility)
• Cartilages (cushion)
• Ligaments (connect bone to bone)

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Functions of the Skeletal System

• Support the body (internal framework)
• Protect soft organs (vertebrae)
• Allow movement due to attached skeletal muscles
• Store minerals and fats (fats, clacium,
  phosphorus)
• Hematopoiesis (Blood cell formation)

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The Skeletal System

• Two subdivisions of the skeleton
• 1. Axial skeleton
• (skull, ribs, spine)
• 2. Appendicular skeleton
• (pectoral girdle, pelvic girdle,
• bones of limbs)

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Classification of Bones by Shape

• Long bones
• Have a shaft with heads at both ends
• Typically longer than they are wide
• Contain mostly compact bone
• Examples
• Femur (longest bone in the body)

Head
Shaft
Head
Figure 5.1a
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Anatomy of a Long Bone

• Diaphysis
• Compact bone
• Protected by periosteum (membrane)
• Epiphysis
• Ends of the bone
• Thin layer of compact bone
• But mainly spongy bone in the middle
• Protected by articular cartilage

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Anatomy of a Long Bone

• Medullary cavity
• Cavity inside of the diaphysis
• Contains yellow marrow
• (mostly adipose) in adults
• Contains red marrow
• (for blood cell formation)
• in infants

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• 2. Short bones
• Generally cube-shape
• Contain mostly spongy bone
• Example
• Carpals
• Tarsals
• Patella

Figure 5.1b
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• 3. Flat bones
• Thin, flattened, and usually curved
• Two thin layers of compact bone inside
• Layer of spongy bone inside
• Example
• Skull
• Ribs
• Sternum

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• 4. Irregular bones
• Irregular shape
• Do not fit into other bone classification
  categories
• Example
• Vertebrae
• Hip bones

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Review

• Bone is a type of connective tissue
• 2 Parts
• 1. Cells (living)
• 2. Matrix (nonliving substance released by
  cells)
• A. Fiber
• B. Ground Substance

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1. Cells

• Osteocytes mature bone cells
• Osteoblasts bone-forming cells (germ cells or
  bud cells)
• Osteoclasts bone-destroying cells (breakers)
• A. primarily collagen fibers
• flexibility
• tensile strength (the strength to endure
  stretching forces)
• B. calcium salts (hardness)
• contain calcium and phosphorus
• great compressional strength (the strength to
  endure squeezing forces)

2. Matrix
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Classification of Bone by Tissue Type

• Two basic types of Tissue
• 1. Compact bone
• Homogeneous
• Looks smooth
• 2. Spongy bone
• Small needle-like pieces of bone
• Many open spaces
• (like sponge)
• Keep bones light

Figure 5.2b
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Microscopic Anatomy of Bone
Figure 5.3a
http//www.youtube.com/watch?v4qTiw8lyYbsNR1
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Microscopic Anatomy of Bone

• Osteon (Haversian system)
• A unit of bone containing central canal and
  matrix rings
• Central (Haversian) canal
• Opening in the center of an osteon
• Carries blood vessels and nerves
• Perforating (Volkmans) canal
• Canal perpendicular to the central canal
• Carries blood vessels and nerves

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Microscopic Anatomy of Bone

• Lacunae
• Cavities containing bone cells (osteocytes)
• Arranged in concentric rings
• Lamellae
• Rings around the central canal
• Sites of lacunae

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Microscopic Anatomy of Bone

• Canaliculi
• Tiny canals
• Radiate from the central canal to lacunae
• Form a transport system connecting all bone cells
  to a nutrient supply

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Microscopic Anatomy of Bone
Figure 5.3bc