Veterinary Anatomy : Osteology

1. Bone Classification Schemes
Development:
a) Endochondral bones — develop from cartilage precursors (most bones)
b) Intramembranous bones — directly from mesenchyme (fascia) (bones of calvaria & face)
Location:
a) Axial skeleton — head, vertebral column ( including tail),ribs & sternum
b) Appendicular skeleton — bones of limbs, including scapula & os coxae(hip bone)
c) Heterotopic bones — os penis [ carnivore; rodent ] os cardis [ cattle ]
Shape:
1) Long bones — length greater than diameter
2) Short bones — approximately equivalent dimensions
3)Flat bones — e.g., scapula, os coxae, many bones of skull
4)Irregular bones — short & multiple processes (vertebrae)
5)Sesamoid bones — small “seed-like” within tendons,e.g., patella (knee cap)

Bone Functions
1)Support-body shape & weight
2) Levers- to perform work
3)Protection of vulnerable organs
4)Ca++ & PO4- -reservoir for ions
5)Red Marrow-source of blood cells

 Bone Composition
1)Collagen fibers-by weight: 1/3 of bone
                              -by volume: 1/2 of bone
2)Hydroxyapatite crystals-(Ca)10(PO4)6(OH)2
3) 95% solid (vs. water)
 4) 65% mineral; 35% organic