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The Skeletal System

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The Skeletal System The rigid framework of the body Clopton Havers (1691) Composition and Structure of Bone Tissue Mechanical functions of bone provides a rigid ... – PowerPoint PPT presentation

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Title: The Skeletal System


1
Chapter 13
  • The Skeletal System
  • The rigid framework
  • of the body

2
Clopton Havers (1691)
It is true, if we come to torture a bone with
the Fire, it seems to confess that it
consists of all the five Chymical Principles...
3
Composition and Structure of Bone Tissue
  • Mechanical functions of bone
  • provides a rigid skeletal framework to support
    and protect other tissues.
  • forms a system of rigid levers (links) that can
    be moved by forces from the attached muscles
    (rotated by torques from the attached muscles).

4
Types of bones (206)
  • Central or axial skeleton
  • skull, vertebrae, sternum, and ribs
  • Peripheral or appendicular skeleton
  • bones of the arms and legs

5
Types of bones (overheads)
  • Short bones
  • limited gliding motions and shock absorption.
  • Small, cubical structures (carpals, tarsals)

6
Types of bones
  • Short bones
  • Flat bones
  • Protection, provide attachment sites
  • Flat in shape (ie scapula)

7
Types of bones
  • Short bones
  • Flat bones
  • Irregular bones
  • Multi-functional
  • odd shapes (ie vertebrae)

8
Types of bones
  • Short bones
  • Flat bones
  • Irregular bones
  • Long bones
  • long shaft and bulbous heads (condyles,
    tubercles, or tuberosities)
  • serve as levers for movement (ie tibia, femur,
    humerus, radius, ulna, clavicle, fibula,
    metatarsals, and the phalanges)

9
Material Constituents
  • Calcium carbonate
  • calcium phosphate
  • collagen
  • water

-stiffness -compressive strength
-flexibility (tensile strength)
-tensile compressive strength
10
Structural Organization (overhead)
  • Cortical bone (compact)--Low porosity
  • 5-30 of bone volume non-mineralized tissue.
  • Trabecular (spongy\cancellous) High porosity
  • 30 to gt 90 volume non-mineralized tissue.

11
Structural Organization
12
Bone Comparison
  • Cortical
  • low porosity
  • more stiff
  • greater stress
  • casing of all bones (epiphysis, irregular)
  • diaphysis of long bones
  • Trabecular
  • high porosity
  • more elastic
  • greater strain
  • interior of all bones

13
Load and Response
  • Stress
  • force per unit area
  • Strain
  • deformation
  • amount of deformation divided by original length

14
Generic Stress-Strain Relationship
15
Bone Stress-Strain Relationship
Plastic Region
Elastic Region
Stress (load)
Fracture Threshold
Strain (deformation)
16
Relative Bone Strength
Compression
Tension
Shear
17
Common bone injuries
  • Fractures - with excessive loads, bone tends to
    fracture on the side loaded in tension.
  • Simple - no break in skin.
  • Compound - protrusion through the skin.
  • Comminuted - fragmentation of the bone.
  • Avulsions - bone chip pulled away
  • Spiral - twisting break.
  • Impacted - opposite ends compressed together.
  • Stress - repeated low magnitude loading

18
Site of Ankle Avulsion Fracture
19
Avulsion fracture of the patella following
B-PT-B repair of the ispsilateral ACL
20
Comminuted Fracture
Low Energy
High Energy
21
Ankle Trouble
22
Three Biological Phases to fracture healing
  • Inflammatory Phase
  • 3 to 7 days
  • immobilize the bone
  • activates cells for repair
  • step by step process that is critical to
    successful union

23
Three Biological Phases to fracture healing
  • Inflammatory Phase
  • Reparative Phase (bony union)
  • about one month
  • callus formation
  • provisional gt bony

24
Three Biological Phases to fracture healing
  • Inflammatory Phase
  • Reparative Phase (bony union)
  • Remodelling Phase
  • restoration of original contour

25
Bone Growth and Development
  • Living bone is dynamic
  • continually changes throughout lifespan.
  • Longitudinal growth
  • length increases occur at the epiphyses
  • epiphyseal plates.
  • produce new bone tissue until closing during
    adolescence or early adulthood.
  • Circumferential growth
  • Bones alter diameter throughout lifespan, with
    most rapid change before adulthood.

26
  • Osteoclasts
  • resorb existing bone
  • Osteoblasts
  • form new bone

Critical factor in bone modelling/remodelling ba
lance of their action
27
Bone Response to Stress
  • Wolff's law (1892)
  • tissue adapts to level of imposed stress
  • increased stress
  • hypertrophy (increase strength)
  • decreased stress
  • atrophy (decrease strength)
  • FORM FOLLOWS FUNCTION
  • Genetics, Body weight, physical activity, diet,
    lifestyle (see note clippings)

28
The pattern of trabecular bone in the greater
trochanter neck of the femur head of the femur
reflects femurs roles muscle
attachment flexibility weight transfer support
29
Atrophy
  • Bone weight strength decreases
  • Calcium content diminishes
  • reduced BMD
  • trabecular integrity is lost

30
Bone stimulating factors
  • Rate of loading
  • Magnitude
  • Frequency

31
Is physical decline inevitable with aging?
32
No. Genetics dominates. But lifestyle modulates
.
33
Changing concept of old age.
34
Osteoporosis slide presentation (Aging(?), OA and
OP)
35
Effect of Peak BMD on osteoporosis
BMD
Fracture Threshold
20
50
80
AGE (years)
36
Effect of Peak BMD on osteoporosis
Menopause
BMD
Fracture Threshold
20
50
80
AGE (years)
37
Effect of Peak BMD on osteoporosis
Typical peak BMD
BMD
Fracture Threshold
20
50
80
AGE (years)
38
Effect of Peak BMD on osteoporosis
BMD
Low peak BMD
Fracture Threshold
20
50
80
AGE (years)
39
Effect of Peak BMD on osteoporosis
High peak BMD
BMD
Fracture Threshold
20
50
80
AGE (years)
40
Effect of Peak BMD on osteoporosis
Can the rate of BMD decrease be altered?
BMD
Fracture Threshold
20
50
80
AGE (years)
41
DEXA Scans
Click here to read about DEXA scans
42
Calcium Intake
Check out this site with information on calcium
and osteoporosis
43
Joint Architecture Classification
  • Synarthoses (immovable)
  • Amphiarthroses (slightly movable)
  • Diarthroses or synovial (freely movable)
  • Get our attention

44
William Hunter (1743)
The bone ends are covered with a smooth
elastic crust, to prevent mutual abrasion
connected with string ligaments, to prevent
dislocation and enclosed in a bag that contains
a proper fluid deposited there for lubricating
the two contiguous surfaces.
45
Synovial Joint Features
  • Articular (hyaline) cartilage
  • covers articulating surfaces
  • no blood vessels
  • no nerves
  • Serves 3 purposes
  • reduces friction
  • increases articulating area to reduce stress
  • shock absorption

46
Synovial Joint Features
  • Articular (hyaline) cartilage
  • Articular (fibrous/joint) capsule
  • double layer membrane surrounds synovial joint
  • outer connects bones
  • inner secretes synovial fluid
  • may have definite ligaments

47
Synovial Joint Features
  • Articular (hyaline) cartilage
  • Articular capsule
  • Synovial fluid
  • clear, slightly yellow liquid
  • lubricates joint
  • nourishes cartilage

48
Synovial Joint Features
  • Articular (hyaline) cartilage
  • Articular capsule
  • Synovial fluid
  • Fibrocartilage
  • disc or partial disc between articulating bones.
  • Intervertebral discs menisci
  • increase surface area reduce stress
  • improve fit of articulating surfaces
  • limits translation or slip of bones
  • shock absorption

49
Synovial Joint Features
  • Articular (hyaline) cartilage
  • Articular capsule
  • Synovial fluid
  • Fibrocartilage
  • Tendon sheaths
  • surround tendons located close to bones
  • reduce stress on tendon
  • maintain low friction

50
Synovial Joint Features
  • Articular (hyaline) cartilage
  • Articular capsule
  • Synovial fluid
  • Fibrocartilage
  • Tendon sheaths
  • Bursae
  • small synovial fluid filled capsules
  • separate tendon from bone to reduce friction

51
Mobility is a very precious gift. More complex
than the space shuttle.
52
Total Hip Implants
Acetabular Component
Polyethylene Liner
Metal Shell
Head
Collar
Stem
Osteotomy Line
Femoral Component
53
Osteoarthritis Slide Show
54
Osteoarthritis Slide Show
Click on the info button to read on NSAIDs
55
Joint Stability
  • ability to resist abnormal displacement of the
    articulating bones
  • Dislocation - bones displace out of their normal
    positions.

Impingement
Subluxation
Dislocation
56
Joint Stability
  • ability to resist abnormal displacement of the
    articulating bones
  • Contributing factors
  • shape of articulating surfaces
  • close-packed position position of max contact
  • knee, wrist, interphalangeal full extension
  • ankle full dorsiflexion
  • loose-packed position position other than c-p
  • most prone to dislocation, cartilage damage

57
Joint Stability
  • ability to resist abnormal displacement of the
    articulating bones
  • Contributing factors
  • shape of articulating surfaces
  • arrangement of ligaments muscles
  • concept of rotary stabilizing components of
    muscle/ligament tension
  • rotary component that causes/tends to cause
    rotation
  • stabilizing acts parallel to the bone

58
Flexibility ROM at a joint
59
Joint Flexibility
  • Factors influencing joint flexibility
  • Shape of articulating bones
  • other soft tissue stiffness mass
  • muscle current tone
  • ligaments arranged in direction of expected pull
  • fatty tissue
  • temperature warmer more pliant
  • past injury collagen alignment integrity
  • clothing
  • AGE??? vs inactivity

60
Why is flexibility important?
  • Basic component of a fitness profile.

61
Why is flexibility important?
  • Basic component of a fitness profile.
  • allows for greater choice of movement patterns
  • slides of gymnasts
  • elderly shoulder ROM independence
  • Osteoarthroses
  • contractures (ie cerrebral palsy)
  • sprain ankle inflammation

62
Why is flexibility important?
  • Basic component of a fitness profile.
  • allows for greater choice of movement patterns
  • reduce risk of injury
  • absorb energy over a greater distance (time)
  • CAVEAT Risk of injury increased with ROM high,
    or low
  • slide next overhead

63
From Cowan et al, 1988, ref 304
64
Why is flexibility important?
  • Basic component of a fitness profile.
  • allows for greater choice of movement patterns
  • reduce risk of injury
  • Increase forceful performance
  • apply force over a greater distance (time)
  • violation of principle of summation of joint
    force
  • violation of principle of IMPULSE

65
Techniques for increasing joint flexibility
Best Advice Use It Dont Lose It
66
How best to stretch?
67
Techniques for increasing joint flexibility
  • Review neural innervation
  • Golgi tendon organs (figure 5-11)
  • located in junctions between muscles and tendons
  • responsive to tension in tendon
  • inhibits tension development in active muscle

68
Techniques for increasing joint flexibility
  • Review neural innervation
  • Golgi tendon organs
  • Muscle spindles (figure 5-12)
  • located parallel to the muscle fibers in the
    belly of the muscle
  • responsive to lengthening of fibers (rate
    length) Stretch Reflex
  • activate stretched muscle, inhibit antagonist
    (reciprocal inhibition)

69
Techniques for increasing joint flexibility
  • Review neural innervation
  • Golgi tendon organs
  • Muscle spindles
  • Flexibility training goal
  • do not invoke stretch reflex (do not activate the
    muscle group to be stretched) HOW???
  • activate golgi tendon organs (further inhibit the
    muscle group to be stretched (reduce tonus))
    HOW???

70
Types of stretching
  • Active - stretching muscles, tendons, ligaments
    by active development of tension in the
    antagonist muscles
  • Passive - stretching muscles, tendons,
    ligaments by a force other than tension in the
    antagonist muscles (gravity, another segment,
    another person)

71
Types of stretching
  • Ballistic - a series of quick, bouncing
    movements.
  • Static - a slow controlled stretch held over time
    (10-30s, 3 to 4 reps)
  • Proprioceptive Neuromuscular Facilitation -
    alternating contraction and relaxation of the
    muscles being stretched.
  • Contract-relax pull-contract
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