Skeletal System
Chapter 5
Components of the Skeletal
System
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Skeleton subdivided
– Axial Skeleton-longitudinal
axis of body
– Appendicular Skeletonlimbs and girdles
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Skeletal System includes
– Joints – 3 types
– Cartilages – 3 types
 Hyaline, Fibrocartilage,
Elastic
– Ligaments – bone to bone
http://www.daviddarling.info/encyclopedia/S/skeleton.html
Functions of Bones
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Support: framework
Protection: protect soft body organs
examples?
Movement: skeletal muscles attached to bones
via tendons
Storage: fats in the internal cavities of bones
and minerals such as Ca++ and Phosphorus.
Blood cell formation: hematopoiesis (blood cell
formation) – marrow cavities of some bones.
Classification of Bones
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Two types of osseous
tissue
– Compact bone-dense,
smooth, homogeneous
– Spongy boneneedlelike pieces of
bone and lots of open
space.
http://www.britannica.com/EBchecked/topic-art/276196/101316/Longitudinal-section-of-the-humerus-showing-outer-compact-bone-and
Classification based on Shape
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Four groups
1) Long bones – longer than wide,
shaft with heads at both ends,
mostly compact bone, all bones of
limbs except patella, wrist, ankle
2) Short bones – cube shaped,
mostly spongy, wrist, ankle,
sesamoid bones
3) Flat bones – thin, flattened,
usually curved, outer layers of
compact bone sandwich spongy,
skull, ribs, sternum
http://www.aclasta.co.nz/osteoporosis/index.htm
4) Irregular bones – don’t fit
previous categories, hip bones,
vertebrae
Structure of a Long Bone
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Diaphysis - shaft
Periosteum - fibrous connective
tissue membrane
Endosteum
Sharpey’s fibers - perforating fibers
connect periosteum to bone
Epiphyses - ends, compact bone
enclosing spongy
Articular cartilage - covers
epiphyses, glassy hyaline cartilagedecreases friction
Epiphyseal line - adult bones,
epiphyseal plate in growing bones,
hyaline cartilage, growth, replaced
by bone in puberty
http://www.curehandpain.com/images/bone/long_bone.gif
Structure of a Long Bone
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Medullary cavity –
1) adults - yellow marrow
2) infants – red marrow
- in adults red marrow
confined to spongy bone of
flat bones and epiphyses of
some long bones
Bone Markings – Table 5.1
projections vs depressions
ex. Trochanter, Foramen
http://www.curehandpain.com/images/bone/long_bone.gif
Microscopic Anatomy of Long
Bone
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http://www.octc.kctcs.edu/GCaplan/anat/images/Image269.gif
Osteocytes – mature
bone cells
Lacunae – cavities where
osteocytes found
Lamellae – circles lacunae
found
Haversian canals – center
of lamellae
Osteon – lamellae +
Haversian canal
Canaliculi
Volkmann’s canals
Microscopic Anatomy of Long
Bone
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Osteocytes – mature
bone cells
Lacunae – cavities where
osteocytes found
Lamellae – circles lacunae
found
Haversian canals – center
of lamellae
Osteon – lamellae +
Haversian canal
Canaliculi
Volkmann’s canals
http://education.vetmed.vt.edu/curriculum/vm8054/labs/Lab8/IMAGES/OSTEON%20AND%20INTERSTITIAL%20SYSTEM.jpg
Bone Formation, Growth, and
Remodeling
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Skeleton formed from
bone and cartilage
Embryos vs young
children
Cartilage remains in
nose, parts of ribs,
joints
Ossification – bone
formation
http://www.personal.psu.edu/staff/m/b/mbt102/bisci4online/bone/bonedevel.jpg
Ossification
Ossification – 2 phases
1) Hyaline cartilage model
covered w/ bone matrix by
Osteoblasts
2) Cartilage digested
opening Medullary cavity
-By birth hyaline cartilage
models coverted to bone
except articular cartilages
and epiphyseal plates
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http://www.personal.psu.edu/staff/m/b/mbt102/bisci4online/bone/bonedevel.jpg
Bone Growth - Lengthening
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New cartilage added 2 places
– external articular cartilage
and ephiphyseal plate
What do each of these do?
Old cartilage digested replaced
by bony matrix
http://www.personal.psu.edu/staff/m/b/mbt102/bisci4online/bone/bonedevel.jpg
Bone Growth - Widening
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Appositional Growth –
diameter increase
Osteoblasts in periosteum add
bone tissues to diaphysis
Osteoclasts in endosteum
remove bone from inner
diaphysis
Occurs at about same rate
Controlled by hormones
Ends in puberty – epiphyseal
plates converted to bone
http://www.personal.psu.edu/staff/m/b/mbt102/bisci4online/bone/bonedevel.jpg
Bone Remodeling
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2 Factors
1) Ca++ in blood – bones as storage
a) below homeostatic levels
– parathyroid glands release PTH into
blood.
- PTH activates osteoclasts
b) above homeostatic levels
- Ca++ deposited as calcium salts
Bone Remodeling
2) pull of gravity and muscles on bone
 Necessary to retain proportions and strength during
growth
 Bones become thicker and form projections where
bulky muscles attached
 No stress – bones weaken and atrophy
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Ca++ uptake/release and remodeling work together
– PTH determines WHEN bone broken down or deposited based
on [Ca++] in blood
– Muscle pull and gravity determine WHERE bone broken down
or deposited
Bone Fractures
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Occur less often in youth,
requires exceptional trauma
– twists or smashes
Two types – simple or
compound
–
–
–
Comminuted – many fragments
Compression – crushed
Depressed – broken bone
portion pressed inward (skull)
– Impacted – broken ends forced
into each other
– Spiral – ragged break due to
twisting
– Greenstick – incomplete break
http://www.hivandhepatitis.com/2008icr/ddw/docs/060308_b.html
http://www.itim.nsw.gov.au/index.cfm?objectid=2A54AE6D-1321-1C29-707811D2028CC580
Bone Repair
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1)
2)
3)
4)
Reduction – closed or open,
immobilization to all healing
Hematoma forms – blood
vessels broken, blood filled
swelling
Fibrocartilage callus
formation – mass of repair
tissue – cartilage matrix,
bony matrix, and collagen
fibers, act as splint
Bony Callus forms –
osteoblasts and osteoclasts
migrate to break, spongy
bone callus forms
Bone Remodeling –
permanent patch due to
stresses
http://1.bp.blogspot.com/_57e2KV2nOZs/SAGetjS3TjI/AAAAAAAAAY8/rvhaSyEf-us/s400/bone+repair.jpg
Axial Skeleton
Bones of Skull
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Cranium + facial
Cranium – encloses
brain tissue
Facial – hold eyes,
facial expressions
Joined by sutures –
immovable joints
1 exception – what is
it?
http://commons.wikimedia.org/wiki/File:Human_skull_side_simplified_(bones).svg
Cranium Bones
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Frontal – forehead
Parietal – most of
cranium, sagittal
suture
Temporal – around
ear, squamous suture
Occipital – floor and
back, lambdoid suture
Sphenoid – butterfly
shaped
http://commons.wikimedia.org/wiki/File:Human_skull_side_simplified_(bones).svg
Facial Bones and Damage
http://www.peidental.ca/cleft.html
Cleft Palate – incomplete Maxillae
formation
http://www.physioweb.org/skeletal/skeletal_struct.html
http://www.cdc.gov/ncbddd/BD/cleft.htm
Infant vs Adult Skull
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Infant
–
–
–
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Face small to cranium
Cranium ¼ body length
Fibrous regions – fontanels
allow compression, brain
growth
Adult
–
–
–
Completely ossified
Fused at sutures
1/8 body length
http://www.waukesha.uwc.edu/lib/reserves/pdf/zillgitt/zoo170/diagra
ms2/diagrams2.html
Vertebral Column
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Axial Support of body
Skull to pelvis
26 vertebrae (which type?)
connected and reinforced by
ligaments
Protects spinal cord
Before birth 33 vertebrae
Separated by fibrocartilage –
intervertebral discs
http://commons.wikimedia.org/wiki/File:Gray_111_-_Vertebral_column-coloured.png
Vertebral Column
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Discs and S-shape
prevent shock to head
and make trunk flexible
Primary curvatures –
thoracic and sacral
regions
– Make C-shape of newborn
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http://www.sleepywrap.com/index.php?page=stroller-baby-carrier
Secondary curvatures –
cervical and lumbar
– Develop after birth
– Allow to center weight
http://commons.wikimedia.org/wiki/File:Gray_111_-_Vertebral_column-coloured.png
Herniated Discs
http://www.cedars-sinai.edu/5274.html
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Drying of discs,
weakening of
ligaments predisposes
older to problem
Also caused due to
exceptional twisting
Pressure from disc on
spinal cord or nerves –
numbness and/or pain
http://myhealth.ucsd.edu/library/healthguide/en-us/support/topic.asp?hwid=zm5009
Abnormal Spine Curvatures
Scoliosis, Kyphosis, Lordosis – All are
either congenital, result of disease, due
to poor posture, or unequal pull of
muscles on spine
http://www.merinews.com/catFull.jsp?articleID=147926
http://www.spineuniverse.com/displayarticle.php/article3094.html
http://www.nytimes.com/imagepages/2007/08/01/health/adam/9583Lordosis.html
Thoracic Cage
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Also known as bony
thorax
Protects organs in
thoracic cavity
Made up of sternum,
ribs, and thoracic
vertebrae
– What kind of bones
are these?
http://academic.kellogg.cc.mi.us/herbrandsonc/bio201_McKinley/skeletal.htm
Ribs
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12 pair
True Ribs – 1st 7 pair
– Attach to sternum via costal
cartilages
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False Ribs – last 5 pair
– Indirectly or not attached to
sternum
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Floating Ribs – last 2 pair
– Lack sternal attachment
Intercostal space – filled with
intercostal muscle
Appendicular Skeleton
Shoulder Girdle
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Consist of 2 bones
– Clavicle – collar bone
– Scapula – shoulder
blades
http://www.digitalartform.com/archives/2004/11/anatomy_practic_6.html
Upper Limbs
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30 bones
Arm
– Humerus
– Which type of bone?
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Forearm
– Radius, Ulna
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Hand
– Carpal (8) wrist
– Metacarpals (1->5)
– Phalanges (14)
http://commons.wikimedia.org/wiki/File:Human_arm_bones_diagram.svg
Pelvic Girdle
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Large and heavy
bones
Attached to axial
skeleton
Bearing weight most
important function
Houses reproductive
organs, urinary
bladder, part of large
intestines
http://classes.midlandstech.com/bio112/figure7.23pelvic%20girdle%20and%20hip%20bone.htm
Lower Limbs
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Thigh
– Femur – heaviest,
strongest bone in body
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Leg
– Tibia, Fibula
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Foot
–
–
–
–
Tarsals (7)
Metatarsals (5)
Phalanges (14)
Supports weight, level
to propel bodies
http://www.nlm.nih.gov/medlineplus/ency/imagepages/8844.htm
Joints
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All bones form joint except 1
2 functions – hold bone
together, mobility
Classified 2 ways
–
Functionally – amount of
movement
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–
Synarthroses - immovable
Amphiarthroses - slightly
Diarthroses – freely
Where would you find each?
Structurally – separation of
body regions at joint
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Fibrous - immovable
Cartilaginous - both
Synovial - freely
http://apps.uwhealth.org/health/adam/sp/13/100006.htm
Joints
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Cartilaginous – bone ends connected by
cartilage
– Intervertebral joints of spine (amphiarthrotic)
– Epiphyseal plate of growing long bone
(synarthrotic)
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Fibrous – boned united by fibrous tissue
– Sutures of cranium, connective tissue
Joints
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Types of Synovial
Joints based on shape
– Shape determines
movement
– Plane, hinge, pivot,
condyloid, saddle, balland-socket
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Synovial – bones
joined by cavity filled
with synovial fluid
– All joints of limbs
http://www.octc.kctcs.edu/gcaplan/anat/Notes/API%20Notes%20I%20Types%20of%20Joints.htm
Diseases of the Joints
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Sprains – ligaments,
tendons damaged,
heal slowly and
painful due to low
blood supply
http://www.epodiatry.com/ankle-sprain.htm
Arthritis – joint inflammation, 100+ diseases,
most widespread degenerative disease.
Acute – bacterial infection, Antibiotics
Chronic – Osteoarthritis, Rheumatoid,
gouty
Osteoarthritis
http://www.csmc.edu/5619.html
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http://www.yorkshirekneeclinic.co.uk/knee-arthritis-treatment.htm
85% elderly
“wear and tear”
Articular cartilage
Bone spurs –
restricted movement
Rheumatoid Arthritis (RA)
http://www.cedars-sinai.edu/5234.html
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http://www.bestglucosamine.co.uk/rheumatoid-arthritis.html
Chronic inflam. Disease
3x women
Joints of fingers, wrists,
ankles and feet
Symmetrical
Auto-immune
Cartilage destroyed, scar
tissue connect bones, ossifies
Gouty Arthritis
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Uric acid accumulates
in blood, deposits
crystals in joints,
Normally affects
single joint
Mostly men, rarely
before 30
http://gouthomeremedies.info/category/uncategorized
http://www.learningradiology.com/notes/bonenotes/goutpage.htm
The End