Skeletal System Bone Basics

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Skeletal SystemBone Basics
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Basics

• Components
• Functions
• Support
• Storage
• Blood cell production
• Protection
• Leverage

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Connective Tissue
4 types - Bone - Cartilage - Hyaline -
Elastic - Fibrocartilage function location
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Classification of Bones
Axial Appendicular
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Classification of Bones - Shape

• Long
• Short
• Flat
• Irregular

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Classification of Bones - Texture

• Compact
• Spongy

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Classification of Bone Texture? Compact Bone

• Surfaces except joints
• Heavy stress areas
• Osteons parallel to
• long axis
• Bend with end force
• Smaller force from side
• can cause breaks

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Classification of Bone Texture? Spongy Bone

• Inner part
• Less dense
• Stress from many directions
• Lighter weight
• Trabeculae
• Hematopoeitic tissue
• red marrow vs. yellow marrow

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Microscopic Features

• Osteocytes
• Lacunae
• Canaliculi
• Osteon
• Around central canal
• Osteoblasts
• Osteoclasts

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Microscopic Structure of Bone Compact Bone
Figure 6.6a, b
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Features of a long bone

• Epiphyses Diaphysis
• Epiphyseal Line
• Compact Spongy bone
• Medullary Cavity
• Endosteum
• Periosteum

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Periosteum

• Outer layer
• Inner layer
• Perforating canals

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Bone Development
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• Describe the structure and function of spongy
  bone
• Describe the structure and function of compact
  bone
• Describe 5 functions of bone

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Bone Remodeling

• 6 wks after fertilization 25 yrs
• Calcium
• 99 in skeleton
• Role in nerve and muscle cells
• 18 of proteins and minerals removed and replaced
  a year
• Remodeling
• Not same rate for all bones
• Important for calcium homeostasis

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Injury and Repair

• Fractures
• Closed (simple)
• Open
• Transverse
• Spiral
• Comminuted

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• As long as blood supply exists
• 4 months year
• Step 1
• Bleeding
• Clot (hematoma) forms
• Kills osteocytes
• Dead bone

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Step 2

• Periosteum and endosteum cells divide
• Migrate to fracture
• Localized thickenings
• Externally produces hyaline cartilage

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Step 3

• Osteoblasts
• Replace cartilage
• Spongy bone at internal callus
• Grows together
• Stabilizes fracture

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Step 4

• Remodeling
• Dead and spongy ? compact
• Good as new
• May be thicker

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Aging

• Bones thinner and weaker
• Osteoblast activity declines
• Osteoclast activity normal
• More lost in epiphyses, vertebrae, jaws
• Fragile limbs, reduced height, loss of teeth

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Osteoporosis

• Reduces bone mass
• Bone formation
• Effected by sex hormones
• Decreases after menopause
• More common in older women
• Slowed, not prevented
• Hormone replacement
• Dietary changes
• Exercise

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Articulations
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Classifications

• Structure or function
• Immovable
• Fibrous or cartilaginous
• Suture
• Gomphosis
• Synchondrosis

• Slightly movable
• Fibrous or cartilaginous
• Syndesmosis
• Symphysis

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Freely movable

• Synovial
• Wide range of motion
• Bones not in contact
• Covered with articular cartilage
• Arthritis
• Fibrous capsule
• Shock absorption
• Menisci
• Fat pads
• Ligaments and tendons
• Bursae

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Movement

• Gliding
• Angular motion
• Flexion
• Extension
• Hyperextension

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• Abduction
• Adduction
• Circumduction

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Rotation

• Pronation
• Supination

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Special movements

• Inversion
• Dorsiflexion
• Opposition
• Protraction
• Elevation

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Classification of Synovial Joints

• Gliding
• Limited rotation
• Clavicles, carpals, tarsals, vertebrae
• Hinge
• Motion in a single plane
• Elbow, knee, ankle, atlas

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• Pivot
• Rotation only
• Atlas and axis, radius and ulna

• Ellipsoidal or condyloid
• Oval articulation in a depression
• Motion in two planes
• Radius and carpals, phalanges and metacarpal or
  metatarsals

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• Saddle
• Opposing faces nest together
• Angular motion, no rotation
• Base of thumb

• Ball-and-socket
• Round head in cup-shaped depression
• Motion in most directions
• Should and hip

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Intervertebral Articulations

• Gliding and symphyseal joints
• Slipped disc
• Condition of discs as we age

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Shoulder

• Ball-and-socket
• Most frequently dislocated
• Several bursae
• Bursitis
• Rotator cuff

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Elbow

• Hinge joint
• Stronger articulation
• Extremely stable
• Interlocking
• Joint capsule
• Reinfored with ligaments

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Hip

• Ball-and-socket
• Articulating surface
• Fibrocartilage pad
• Fat pad
• Synovial membrane
• Ligaments
• Joint capsule
• Fractures
• Common in elderly
• Dislocation

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Knee

• Hinge joint
• Fibrcartilage pads
• Minisci
• Fat pads
• Burae
• Patella within ligament
• Surrounded by ligaments
• ACL