As soon as you come in!Define these words

OsteonHaversian Canal

LamellaOsteocytecanaliculi

Microscopic Anatomy of the Bone• The Structural Unit of Compact Bone is called

• Osteon or Haversian System

Functional unit of the team

• Has concentric tubes of bone matrix called

lamellae • surrounding a central canal that serves as a

passageway for blood vessels and nerves.

• Volkmann’s (perforating) canals lie at right angles to long axis

• connect the blood and nerve supply of the periosteum to these central canals and medullary cavity.

Mr. Verdi’s baby’s head

• Osteocyctes occupy lacunae at the junction of lamellae.

• Circumferential lamellae = just beneath the periosteum around the entire circumference of bone.

• Interstitial Lamellae = lie between intact osteons filling the space in between

• Spongy bones lacks osteons, but has trabeculae that align along lines of stress.

Bone Composition

• Organic: • A. osteogenic, osteoblasts, osteocytes,

osteoblast -- all cell types• B. Osteoid -- ~1/3 of matrix including ground

substance and collagen fibers• Resilent and great tensile strength “sacrificial

bonds” dissipate energy thus preventing fractures

• Inorganic: ~65% by mass of inorganic salts. Mainly calcium phosphate crystals. This accounts for the hardness of bones which resists compression. Drink your milk!!

• This mix of collagen, proteins, and minerals makes bone durable and strong.

• ½ as strong as steel at resisting compression and just as strong as resisting tension.

• And obviously bones remain long after death, leaving remains that allow us to study humans from the past