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Classification of Bones by Shape
- Long
- - longer than they are wide
- - shaft + two ends
- - includes most of the limb bones!
- Short
- - roughly cube shapes
- - wrist and ankle bones
- - sesamoid bones are a specialized type of short bone; forms in a tendon; i.e. patella
- Flat
- - thin, flattened, a bit curved
- - scapulae, sternum, shoulder blades, ribs, most skull bones
- Irregular
- - don't fit in elsewhere
- - vertebrae, hip bones, sphenoid and ethmoid bones
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Osteon Structure
Haversian/Central Canals: central canal of osteon; allow passage of blood vessels, lymphatic vessels, nerve fibers
Lamella: tube that surrounds central canal; contains collagen fibers that all run in the same direction; adjacent lamella have fibers running in opposite direction
Lacunae: cavities containing osteocytes, connected by canaliculi
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Compare spongy bone and compact bone.
- Compact Bone- dense bone
- - contains osteons
- - collagenous protein fibers and mineral deposits of calcium phosphate salts
- Spongy Bone- red bone formation occurs in the spongy bone of the skull, ribs, sternum, vertebrae and in the ends of the long bones
- - trabeculae help resist stress as much as possible; no osteons
- - appears more poorly organized than compact bone
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Structure and Function of Intervertebral Discs
- Structure
- - cushionlike pad made of
- - nucleus pulposus; gelatinous, gives the disc its elasticity
- - anulus fibrosus; surrounds NP, limits NP expansion when spine is compressed; binds successive vertebrae together, resists tension in spine, withstands twisting forces
- Function- shock absorbers
- - help spine flex, extend, bend laterally
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What are abnormal curvatures of the spine?
scoliosis (abnormal lateral curve)
kyphosis (hunchback)
lordosis (swayback)
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Curvatures of the Spine
- Posteriorly Concave Curvatures
- - cervical
- - lumbar
- Posteriorly Convex Curvatures
- - thoracic
- - sacral
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What are the functions or paranasal sinuses?
- - lightens the skull
- - warm and moistens the air (through mucus!)
- - enhance resonance of voice
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Elastic Cartilage
Where is it found?
How does it work?
Where: cartilage of the ear
How: similar to hyaline cartilages, but contain elastic fibers
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Fibrocartilage
Where is it found?
How does it work?
Where: Pubic symphysis
How: collagen fibers have great tensile strength
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Hyaline Cartilage
Where is it found?
How it works?
Where: Tip of the nose, costal cartilage of ribs, articular cartilage of a joint, thyroid cartilage, cricoid cartilage
How: provides support, flexibility, and resilience (most abundant)
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What are the types of skeletal cartilage?
- 1.) hyaline cartilage
- 2.) fibrocartilage
- 3.) elastic cartilage
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