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The Skeletal System:The Framework
6
Skeleton’s FunctionSkeleton’s Function
• Provides support and structure• Allows us to move• Protects soft body parts• Produces blood cells• Stores minerals and fats
Bones are primary components
of the skeleton
Although composed of nonliving minerals such as calcium and phosphorus, bones are very much alive, constantly building and repairing themselves
Bones-IntroBones-Intro
The word skeleton comes from
Greek word meaning "dried-up body"
Bones-IntroBones-Intro
Classified according to their shape
Long bones: longer than they are wide and can be found in arms and legs
General Bone General Bone ClassificationsClassifications
Classified according to their shape
Short bones: fairly equal in width and length and found mostly in wrists and ankles
General Bone General Bone ClassificationsClassifications
Classified according to their shape
Flat bones: thinner and can be either flat or curved; plate like in nature and would include skull, ribs, and breastbone (sternum)
General Bone General Bone ClassificationsClassifications
Classified according to their shape
Irregular bones: like parts of jigsaw puzzle, odd in shape; include hip bones and vertebrae
General Bone General Bone ClassificationsClassifications
Figure 6-1
Various bone shapes.
Periosteum (around bone)
Tough and fibrous connective tissue covering bone
Contains blood vessels, which transport blood and nutrients to nurture bone cells, lymph vessels, and nerves
Acts as anchor points for ligaments and tendons
Bone AnatomyBone Anatomy
Bone AnatomyBone Anatomy
Epiphysis and diaphysis Epiphysis: bone end Diaphysis: region between
or "running through" two epiphyses; also called shaft
Hollow region in diaphysis (medullary cavity or canal) acts as storage area for bone marrow
Bone marrow
Red marrow: makes blood cells
Yellow marrow: high fat content; can convert to red marrow in emergency
Bone AnatomyBone Anatomy
Figure 6-2Basic bone anatomy.
• Periosteum• Epiphysis• Diaphysis• Medullary• Red Marrow• Yellow Marrow
PA/Instructor Asks:
A. ErythropoetinB. ElectrophoresisC. HemorrhageD. Hemopoiesis
Bone TissueBone Tissue
Bone TissueBone Tissue
Each unit or osteon
has mature bone cells (osteocytes) forming concentric circles around blood vessels
Area around osteocyte filled with protein fibers, calcium, and other minerals
Bone Tissue-CompactBone Tissue-Compact
Osteons run
parallel to each other; blood vessels laterally connect with them to ensure there is sufficient oxygen and nutrients for bone cells
Bone Tissue-CompactBone Tissue-Compact
Trabeculae are
bars and plates with holes in the middle to make the bone lighter and create space for marrow to form red blood cells
Bone Tissue-SpongyBone Tissue-Spongy
Trabeculae
Figure 6-3Comparison of compact and
spongy bone.Compact•Osteons with•Osteophytes•Connected by blood and lymph vessels
Spongy•Trabeculae formed by bars and plates•Hollow to give space for marrow
Bone is not perfectly
smooth; has variety of projections, bumps, and depressions Projections act as
points of attachment for muscles, ligaments, or tendons
Surface Structure of Surface Structure of BonesBones
Grooves and depressions act as pathways
for nerves and blood vessels
Surface Structure of Surface Structure of BonesBones
Ossification (osteogenesis): formation of
bone in the body Bones grow longitudinally to develop
lengthen and horizontally (wider and thicker) so they can efficiently support body weight and any other weight we support
Bone Growth and Bone Growth and Repair-OsteogenesisRepair-Osteogenesis
Osteoprogenitor cells: nonspecialized cells
found in periosteum, endosteum, and central canal of compact bones; can turn into other types of cells as needed
Non-Specialized CellsNon-Specialized Cells
Bone Growth and Bone Growth and Repair-Cell TypesRepair-Cell Types
Bone Growth Bone Growth and Repairand Repair
Osteoblasts actually form bone and secrete a matrix of calcium and phosphate
Bone Growth and Bone Growth and RepairRepair
Osteocytes mature bone cells that started as osteoblasts; osteoblasts surround themselves
with matrix of calcium that helps them become mature osteocytes
Osteoclasts: believed to originate from type
of white blood cell called monocyte found in red bone marrow; job is to tear down bone material and help move calcium and phosphate into the blood
Bone Growth and Bone Growth and RepairRepair
FOUR Cells of Bone Growth
PA/Instructor Asks:PA/Instructor Asks:
A. OsteoblastsB. OsteoclastsC. OsteogenitorD. Osteoporosis
Bone development and growth begins in the
womb through intramembranous and endochondral ossification
Bone Growth Bone Growth and Repairand Repair
Watch video “Skeletal System Bone Formation”
http://www.youtube.com/watch?v=PIT8zIWmSiI
Bone Growth and Bone Growth and RepairRepair
Figure 6-4Endochondral ossification of
long bone.
• Begins before birth• Periosteum surrounds the
“cartilage bone”
• Cartilage breaks down and osteoblasts create spongy bone in primary ossification region
Figure 6-4Endochondral ossification of
long bone.
• Meanwhile other osteoblasts form compact bone under periosteum.
• Osteoclasts then break down the spongy bone of diaphysis (shaft) to create medullary (middle) of bone
Figure 6-4Endochondral ossification of
long bone.
Epiphyseal plate is thin
band of cartilage that
forms between primary and secondary ossification
centers
Epiphyseal plate (growth plate)exists as
long as bones need to lengthen and widen
Bone Growth and Bone Growth and RepairRepair
PA/Instructor Asks:PA/Instructor Asks:
A. CalciumB. Vitamin DC. FluorideD. Caffeine
*Read “Osteoporosis on Page 122
Figure 6-5A normal bone compared to an
osteoporotic bone.
Special form of dense connective tissue
that can withstand fair amount of flexing, tension, and pressure
CartilageCartilage
Flexible part of nose and ears are cartilage
CartilageCartilage
Makes flexible connection
between bones, as between breastbone and ribs, allowing chest to flex during deep breathing
CartilageCartilage
Acts as cushion
between bones; articular cartilage located on ends of bones and acts as shock absorber,
preventing ends from grinding together when you move
CartilageCartilage
Figure 6-6Articular cartilage and synovial joint.
At this location, a small sac, called bursa, secretes lubricant called synovial fluid
Joints can wear out and become inflamed
despite all this protection, resulting
in arthritis or osteoarthritis
Articulation/JointsArticulation/Joints
When two or more bones join together they form a
joint or articulation
When two or more bones join together they form a
joint or articulation
Ligaments: tough, whitish bands that connect
from bone to bone; can withstand heavy stress
Joints and LigamentsJoints and Ligaments
Tendons are cordlike structures that attach
muscle to bone
Joints and TendonsJoints and Tendons
Types of JointsTypes of Joints
Types of JointsTypes of Joints
Figure 6-7Types of Synovial joints.
Hinge: movement in ONE direction; knee and elbowBall & Socket: lots of movement; shoulder and hipPivot: rotation only is possible; neck or radius/ulnarEllipsoid joint: two areas of movement through same bone; wrist, knuckles
Figure 6-7Types of Synovial joints.
Gliding: flat & platelike that slide black and forth; scapula, wrists and ankles
Saddle: bone shaped like saddle sits over another like a horse; 1st metacarpal or thumb or the carpal bone
Figure 6-8Classification of joint movements.
Hyperextension: joint forced to straighten beyond its normal limitsAbduction: moving away from body's midlineAdduction: moving toward midline of bodyInversion: turning foot inward toward other footEversion: turning foot outward away from opposing foot
Figure 6-8Classification of joint movements.
Supination: turning hand palm upPronation: turning hand palm downCircumduction: combination of movements in the circular arm movement of a pitcherProtraction: movement of part forwardRetraction: motion of drawing part backwardRotation: when bone "spins" on its axis
Figure 6-8Classification of joint movements.
Flexion: bending a joint and decreasing angle between involved bonesExtension: straightening a joint; angle between involved bones increases Plantar flexion: pointing toes down Dorsiflexion: bending foot up toward the leg
Figure 6-9The anterior and posterior
human skeleton.
Axial skeleton (80)•thorax,•spinal column,•hyoid bone,•bones of middle ear,•SkullAppendicular (126)•Arms• legs• hips•shoulder
Figure 6-10Bones of the skull.
Protects and houses brain; has openings
needed for sensory organs (eyes, nose, and ears)
Contains mouth, common passageway for both
respiratory and digestive systems
Fibrous cartilage allows for some flexibility of
bones surrounding the brain
Figure 6-10 (continued)Bones of the skull.
Figure 6-10 (continued)Bones of the skull.
Figure 6-11The bony thorax.
The Bones of chest form thoracic "cage" that provides support and protection for heart,
lungs, and great blood vessels
Figure 6-11The bony thorax.
Cage is flexible due to cartilaginous connections that allow for movement during the
process of breathing
Sternum (breastbone) is location for performing chest compressions during
CPR, compressing heart between sternum and bones of vertebrae
The Bony ThoraxThe Bony Thorax
Figure 6-12The spinal column.
Also called vertebral column; super highway for
information traveling to and from the central nervous system
7 cervical vertebrae
in neck area 12 thoracic vertebrae
in upper back 5 lumbar vertebrae in
lower back 5 sacral vertebrae
midbuttock region 1 tailbone or coccyx is
3-5 small bones fused
The Spinal ColumnThe Spinal Column
At birth, vertebral column concave to front,
like a fetal position (primary curvature) Curvature changes as infant learns to hold its
head up, as well as starts to walk, curving in opposite direction
The Spinal ColumnThe Spinal Column
From two years onward,
vertebral column develops secondary curvature in neck, primary curvature in
upper back, secondary curvature in lower
back, primary curvature in midbuttocks and
tailbone regions
The Spinal ColumnThe Spinal Column
Figure 6-13Spinal disfigurements compared
to healthy spinal curves.
Figure 6-14Bones of the upper and lower
extremities.
Appendicular region consists of arms and legsThese areas perform most of the body movement, making them more vulnerable to sport-related injuries
Figure 6-14Bones of the upper and lower
extremities.
Pelvic girdle different for women than menWomen have greater pubic angle, which
facilitates childbirth, and broad girdle to
support extra weight of child
Pelvis consists of: ilium, ischium, pubis
Fracture is any break in a bone Types of fractures
Simple (closed): break without puncture to skin Compound (open): fracture in which bone has
been pushed through skin Hairline: fine fracture that does not completely
break or displace bone (looks like hair on x-ray)
Pathology Connection: Bone Pathology Connection: Bone Fractures and HealingFractures and Healing
Types of fractures
Greenstick: incomplete breaks, more common in children
Comminuted: when bone has been fragmented or splintered
Pathology Connection: Bone Pathology Connection: Bone Fractures and HealingFractures and Healing
Compound or open fractures are
particularly nasty because deep tissue has potential to be exposed to bacteria once bone is set into place; chance for infection in addition to break is increased
Pathology Connection: Bone Pathology Connection: Bone Fractures and HealingFractures and Healing
Bones take several weeks to heal; can only
heal normally if ends of bones are touching If bones are not touching (poorly aligned),
bone must be set (reduced) Traction may be used to treat fractures of
long bones
Pathology Connection: Bone Pathology Connection: Bone Fractures and HealingFractures and Healing
Watch video “Fracture Healing”http://www.youtube.com/watch?v=TYNGyZrUXEk
A somewhat frail 76-year-old female visits her
physician's office for an annual check-up. Her social history shows she smokes a pack of cigarettes a day and is a heavy coffee drinker.
Case StudyCase Study
She has had several fractured bones in the
last five years that required medical attention. During initial examination, measurements show that the patient has lost approximately an inch of height over the past year. She has also lost several pounds but states she still wears the same size clothes.
Case StudyCase Study
What possible bone disease do you think she
is exhibiting? Describe the bone changes in this condition on
a macro and cellular level (page 122) What treatments and/or lifestyle changes
would you suggest?
Case StudyCase Study
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