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Reading assignment:
Chapter 7, 8, & 9
(Thibodeau & Patton
Anatomy
& Physiology) |
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ACT
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Interactive
activity |
GA |
Gray's Anatomy |
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Animation |
pp |
PowerPoint
slide |
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FIG
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Figure |
term |
Define,
pronounce |
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Online previews:
Skeleton
Joints
(Previews are found at
WebCT)
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Functions
of the skeletal system
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Support
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Framework of body, holding other organs in place |
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Movement
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Attachment sites for skeletal muscles |
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Movable joints; leverage for movement |
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Protection
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Hard covering of thoracic organs, brain, spinal
cord, other soft structures |
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Protection as is bodily defense against injury |
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Mineral and fat storage
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Calcium & phosphorous salts stored in bone
tissue |
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Yellow fat (yellow bone marrow) stored in bone
cavities |
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Blood cell production
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Hematopoiesis (hemato = "blood"
poiesis
= "making") |
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Red bone marrow is blood-forming tissue inside
some bones |
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Bone organs
(gross structure)
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206 bones is standard / typical (but nearly everyone
has more/fewer) |
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Axial skeleton: forms "axis" of body
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Includes bones of skull, vertebral column, thorax |
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Appendicular skeleton: forms appendages (arms, legs)
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Includes bones of shoulder/arm/hand and
hip/leg/foot |
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Bone categories
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Long bones |
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Short bones |
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Flat bones |
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Irregular bones |
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Typical long bone
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Epiphyses (sing. epiphysis) are end regions
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Usually have spongy bone on inside, compact
bone on outside |
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Diaphysis is middle "shaft" region
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Usually compact bone on outside, cavity on
inside |
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Medullary cavity contains yellow marrow
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Lined with thin membrane called endosteum |
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Bone covered with periosteum (dense fibrous
sheet) and articular (joint) cartilage |
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Bone
tissue (microscopic structure)
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Compact bone - hard bone forming outer shell of all
bone organs
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Bone matrix is collagen fibers with apatite
mineral (calcium/phosphorus) crystals encrusted on the fibers
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Always starts out as fibrous membrane or
cartilage, then turns to bone
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Endochondral ossification - cartilage
becomes bone
GA
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Epiphyseal plate is cartilage between
epiphysis and diaphysis as they grow together |
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Intramembranous ossification - membrane
becomes bone
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Fontanels are "soft spots"
in infant skull where ossification is not complete
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Allow for deformation of skull
during childbirth |
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Osteon (haversian system) is a tapered,
cylindrical unit that makes up compact bone tissue
GA
pp
| Central (haversian) canal surrounded by
concentric lamellae (layers) of hard bone matrix
GA
GA
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Transverse (Volkmann's) canals connect
central canals side to side, forming blood networks |
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Osteoblasts ("bone makers") make
matrix, then are trapped and now "retired" and
called osteocytes ("bone cells")
GA
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Lacuna (pl. lacunae) are the spaces in
which osteocytes are found |
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Osteocytes may "come out of
retirement" during remodeling |
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Canaliculi ("tiny canals") connect
the lacunae (each housing one osteocyte) to each other and to
the central canal |
•Around
21 million osteons in
adult skeleton
•Each
osteon is 100-400 µm
in diameter (1 inch = 25,400 µm)
•A
medium osteon has about
30 lamellae (each about 3 µm)
•The
central canal is around
50 µm in diameter
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Spongy (cancellous) bone
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Made up of irregular trabeculae of hard bone
surrounded by red bone marrow (liquid) |
| Red marrow is myeloid tissue
(myelo =
"marrow")
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Hematopoiesis |
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Compact Bone
(osteon highlighted in green)
Click to enlarge |
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Osteon
(closer view)
Click to enlarge |
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Remodeling
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Bone is constantly being torn down and built up
--this is remodeling pp |
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Role of bone cells
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Osteoblasts make new bone matrix (using Ca++
from blood) |
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Osteoclasts ("bone breakers") dissolve
bone matrix (releasing Ca++ to blood) |
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Role of hormones
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Calcitonin (CT; from thyroid) increases Ca++
storage (out of blood) |
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Parathyroid hormone
(PTH) gets Ca++
out of storage (into blood) |
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Age effects
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More bone is made than
is lost until age 25 (usually
rapid until puberty, then slows) |
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About as much bone
is made as is lost 25-50 (can vary) |
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More bone is lost than
is made 50-120 (usually slight) |
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Stress effects
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Mechanical stress can affect bones (fractures,
pressure, exercise, etc.) |
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Stress increases bone density (therefore, gravity
and exercise increase bone density) |
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Usually accounts for changes in bone density in
old age |
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Skeletal variations
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Sex
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Male - heavier, larger; more defined markings;
deep pelvis |
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Female - lighter, smaller; less defined markings;
shallow/broad pelvis |
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Age (see section above) |
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Environment
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Toxins |
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Stress (including fractures) -- see above |
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  A
good place to study normal variations in human skeletons is in the
underground ossuary (place for bones) in Paris --also known as the
"Paris catacombs." Skeletal remains of
thousands of people buried in 18th century cemeteries were moved to
abandoned chalk quarries under the streets of Paris and can be visited
today. Click each photo to enlarge Curious about the Paris
catacombs? Click
here.
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One
frontal bone or two?
Figure A is a
photograph from the Paris catacomb showing a skull with a sagittal suture
separating the frontal part of the skull into a left frontal bone and
right frontal bone.
Figure B is a
photograph of a nearby skull that is "standard" in that it has
no sagittal suture dividing the frontal bone --it has a single frontal
bone.
It is very likely that neither individual was aware of
these facts while they were alive. This is an example of how the
human skeleton can vary from one person to another.
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Joints (see Tables
9-1, 9-2 and 9-3 in
text)
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Definition
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Joint is where two or more bones come together
(join) |
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Arthro = joint
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Arthritis = joint inflammation (many causes /
types)
pp |
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| Ligaments
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Fibrous
structures that connect one bone to another
GA
GA |
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Structural categories
pp
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Fibrous - bones are joined by fibrous tissue |
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Cartilaginous - bones are joined by cartilage |
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Synovial - bones are joined at a fluid-filled
space lined with synovial membrane |
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Functional categories
pp
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Immovable - bones don't move relative to one
another
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Synarthroses |
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Slightly movable - bones can move, but not much
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Amphiarthroses |
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Freely movable - bones have significant movement
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Diarthroses |
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Fibrous (are synarthrotic)
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Syndesmoses
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Fibrous bands called ligaments connect the
bones |
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Example: joints between the distal radius and
ulna
GA
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Sutures
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Fibrous tissue connects flat bones that fit
together like jigsaw puzzle pieces |
| Example: joints between flat bones of skull
GA
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Gomphoses
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Fibrous tissue connects root of tooth to
socket of jaw bone
GA
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Cartilaginous (are
amphiarthrotic)
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Synchondroses
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Hyaline cartilage between bones |
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Example: rib-sternum joint
GA |
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Symphyses
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Fibrocartilage between bones |
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Examples:
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between BODIES of
vertebra
GA
GA |
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pubic
symphysis
GA
GA |
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Synovial (are diarthrotic)
GA
GA
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Uniaxial - single axis of movement
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Biaxial - two axes of movement
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Saddle
GA |
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Condyloid
GA |
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Multiaxial - multiple axes of movement
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Ball and socket
GA
GA |
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Gliding
GA |
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Bursa
GA
GA |
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Types of movements
pp
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Angular movements - increase or
decrease the angle of a joint
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Flexion - decreases angle of
joint
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Ankle flexion - special
case
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Plantar flexion
- moves toes inferiorly |
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Dorsiflexion
- moves toes superiorly |
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Extension - increases angle
of joint
| Hyperextension
- goes beyond anatomical position |
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| Abduction - moves
part away from midline of body or region |
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Adduction - moves toward from midline of body or region |
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| Circular movements -
move body parts in a circle
| Rotation - pivots
part on its axis |
| Circumduction -
moves distal end of part in a circle-like path |
| Supination -
twisting of limb (e.g. arm or leg) away from median |
| Pronation -
twisting of limb toward median |
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Gliding movement |
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Special movements
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Ankle movements
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Inversion - move
sole toward median |
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Eversion - move
sole away from median |
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Forward and back movements
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Protraction -
move part anteriorly |
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Retraction -
move part posteriorly |
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Up and down movements
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Elevation - move
part superiorly |
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Depression -
move part inferiorly |
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This Learning Outline may be
updated or improved at any time.
Check back frequently or use the
link to the right to inform you of changes. |
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© 1988-April, 2007 Kevin
Patton
ALL rights
reserved This page updated
04/01/07.
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