Transcript 3. Bones, Cartilage, Fractures

Long Bone Anatomy
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Diaphysis: Shaft of the bone
– Made of compact bone
Epiphysis: Ends of the bone
– Made mostly of spongy bone
– There is a little compact bone on the outer surface
Articular Cartilage: cap of hyaline cartilage on each epiphysis
which articulates with the next bone
Medullary canal: contains fat
Periosteum: thin layer like an onion-skin that wraps around the
bone. It is anchored to the bone by fibers called Sharpie’s fibers.
Nutrient foramen is in the shaft to allow passage for nutrient
artery to the bone.
Long Bones Contain Spongy and
Compact Bone.
Compact Bone Anatomy
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Compact bone is organized into cylinders
called osteons.
The functional unit of compact bone is the
osteon. It is the functional unit because all of
the osteon’s functions occur within the
osteon.
Compact
Bone
Osteon (cylinders)
Osteon Anatomy
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Osteoblasts are immature bone cells.
They first arrive through the nutrient artery in the
embryo bone when it is still made out of cartilage.
Osteoblast cells are shaped like stars. They align
themselves in concentric circles, as though they are
holding hands. One ring of osteoblasts form a large
circle, then the next ring inside is smaller, with a
smaller ring inside that, and so on. The rings they
form are called lamellae (from the word “laminate”,
which means to lay on top of something. The rings
lay on top of each other).
Compact
Bone
Lamella (rings)
Osteoblasts mature into
osteocytes
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The osteoblasts start to secrete
hydroxyapatite (calcium and phosphate,
which is bone) outside of themselves.
When they do this, they become trapped in
the cave that they have made out of bone.
They are now called osteocytes (mature
bone cell).
They cave they are trapped in is called a
lacunae.
Compact
Bone
Osteocytes (mature
bone cells) trapped
in their lacunae
(caves)
Osteon Anatomy
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Each osteocyte is star shaped, so they seem
to have arms and legs. These appendages
also are trapped in the bone cave, so they
form little canals.
These canals that hold their arms and legs
are called canaliculi (little canals).
Canaliculi are needed to allow for diffusion of
nutrients and wastes between the
osteoblasts.
Canaliculi (little
canals) hold the
arms and legs of
the osteocytes
Osteon Blood Supply
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The nutrient artery, which entered the shaft
of the bone, branches out and one branch
runs through the center of each osteon.
The canal in the center of each osteon which
contains the artery is called the Haversian
canal, or central canal.
The blood supply needs to connect to the
adjacent osteons, so there is a transverse
canal, called Volkmann’s canal, or the
perforating canal.
Haversian (central)
canal
Volkmann’s
(perforating) canal
Spongy Bone: Epiphysis
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Instead of osteons,
spongy bone has
trabeculae (open
spongy network
which allows blood
vessels to pass)
Bone Cells
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Osteoblast (makes bone)
Osteocyte (mature bone cell)
Osteoclast (reabsorbs bone)
Tendons and Ligaments
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Tendons attach muscle to bone. Tendons are not
muscle tissue; they are connective tissue.
Ligaments attach bone to bone.
Tendons and ligaments are both made from dense
regular connective tissue.
An aponeurosis is a modified tendon that flares out
and attaches into connective tissue instead of bone.
There is one that attaches the frontalis muscle
(raises eyebrows) to the skull. Another one is in the
palm of the hand.
Tendon: dense reg. CT
Terms to Know
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Osteon: functional unit of compact bone.
hydroxyapatite The crystalline structure of calcium and
phosphate that make up bone matrix
lamellae The circular and concentric layers of collagen fibers
lacunae The pockets or cavities in which the cells are trapped
Haversian (or central) canal The large channels containing a
blood vessel which run longitudinally down the center of each
unit
canaliculi The “tiny channels” which run transversely through
the layers of bone and allow for diffusion of nutrients and
wastes to the cells
perforating canal: connects one Haversian canal to another
osteocytes The mature bone cells which are trapped in the
matrix and help to maintain it
Osteoblasts: bone cells that lay down new bone
Osteoclasts: bone cells that reabsorb bone
Terms to Know
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Periosteum (secured to the bone by Sharpey’s fibers)
Sharpey’s fibers (anchor the outer wrapping to the bony
matrix below it)
Articular Cartilage (cap around long bone)
Epiphysis (ends of long bones)
Diaphysis (shaft of long bone)
Medullary Cavity (hollow area inside long bone)
Spongy Bone (contains trabeculae instead of osteons and
lamellae)
Trabeculae (web-like formation, like a sponge)
Tendon (attaches muscle to bone)
Ligament (attaches bone-to-bone)
Aponeurosis (modified tendon)
Cartilage and
Bone
Structure and
Function
Bone Characteristics
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Vascular (has own blood supply)
Regenerates well (because it is vascular)
Contains hydroxyapatite (calcium and
phosphate)
Forms mostly after birth
Is not flexible
Formation of Endochondral
(Embryonic) Bone
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In the embryo, hyaline cartilage develops in
the general shape of the future bone.
Periosteum forms on the outside of the
developing bone.
Osteoblasts enter through the nutrient artery
and deposit bony tissue in place of
disintegrating cartilage.
Two Centers of Ossification
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Primary Ossification
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Starts in diaphysis; turns cartilage into bone.
Then the medullary canal hollows out
Secondary Ossification
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Starts in epiphysis; turns cartilage into bone
It leaves behind a growth plate (epiphyseal line)
to allow the child’s bone to grow
Types of Bones
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Long Bones
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Sesamoid Bones
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Develop inside tendons and near joints
Flat Bones
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Arms and legs
Skull bones and scapula
Irregular Bones
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Vertebrae
Cartilage
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What are the three types of cartilage and
where in the body can each of these three
types of cartilage be found?
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Hyaline cartilage (most of the joints)
Fibrocartilage (vertebral discs, pubic symphysis)
Elastic cartilage (ears)
What type of cartilage does an embryonic
skeleton have?
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Hyaline
Cartilage Characteristics
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Avascular (no blood supply)
Does not regenerate well (because it is
avascular)
Contains no calcium
Begins conversion to bone before birth
Is flexible
Joint Disorders and Joint Injuries
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Structure of joints makes them prone to traumatic stress
Function of joints makes them subject to friction and wear
Affected by inflammatory and degenerative processes
Sprains – ligaments reinforcing a joint are stretched or torn
Dislocation – occurs when the bones of a joint are forced
out of alignment
Torn cartilage – common injury to meniscus of knee joint
Inflammatory and Degenerative
Conditions
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Bursitis – inflammation of a bursa due to injury or friction
Tendonitis – inflammation of a tendon sheath
Arthritis – describes over 100 kinds of joint-damaging
diseases
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Osteoarthritis – most common type – “wear and tear” arthritis
Rheumatoid arthritis – a chronic inflammatory disorder
Gouty arthritis (gout) – uric acid build-up causes pain in joints
Lyme disease – inflammatory disease often resulting in
joint pain; Lyme disease is caused by a bacterium and is
transmitted to humans by the bite of infected blacklegged ticks.
Typical symptoms include fever, headache, fatigue, and skin rash.
If left untreated, infection can spread to joints, the heart, and the
nervous system.
Osteoporosis: loss of minerals
Normal Bone
Osteoporosis
Figure 6.15
Stages
of Healing
a Fracture
Four
Stages
of Fracture
Repair
Blood
escapes
Fibrous
callous
Spongy
Bone
callous
Osteoclasts
remove
excess bone
Figure 6.14
Fractures
CLASSIFICATION OF FRACTURES
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SIMPLE (or closed)
– Skin is not broken
– Requires cast
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COMPOUND (or open)
– Bone has broken through the skin
– Increased chance of infections, which can be lifethreatening.
– Requires surgery, hospitalization and IV
antibiotics
CLASSIFICATION OF FRACTURES
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INCOMPLETE
– Only one side of the bone is broken
 Examples
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Hairline (stress) fracture
– Greenstick fracture
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COMPLETE
– Both sides of bone is broken
– Then describe if it is displaced or non-displaced
CLASSIFICATION OF FRACTURES
Once you have
described if the
fracture is open or
closed, and
complete or
incomplete, then
you describe the
fracture shape:
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Stress (hairline) fracture
Greenstick fracture
Epiphyseal fracture
Transverse fracture
Oblique fracture
Spiral fracture
Comminuted fracture
Avulsion fracture
Impacted fracture
Compression fracture
Depression fracture
Types of Fractures
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http://www.youtube.com/watch?v=c5Q5G
PwAS4k
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http://www.youtube.com/watch?v=29V58e
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STRESS FRACTURE
STRESS FRACTURE: least serious, get tiny, almost
invisible breaks. Usually from overexertion. Muscle
builds up faster than bone. Six weeks into military
basic training camp, see lots of stress fractures from
too much new running.
Can’t see it on x-ray for three weeks. Diagnose it by
placing a tuning fork on the bone, but not at the area
of tenderness…the vibration travels down the shaft
of the bone until it reaches the fracture site. This will
be very painful if it is a stress fracture.
Stress Fracture, 3 weeks later
GREENSTICK FRACTURE
GREENSTICK FRACTURE: most common in children;
like breaking a green twig, it’s not completely broken.
It breaks on one side but bends on the other. Bones
in children are not fully mineralized.
Table 6.1
Epiphyseal Fracture
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EPIPHYSEAL FRACTURE
The growth plate in the bone of a child is called the
epiphyseal growth plate. That area is weaker than
bone, so the whole thing can be broken through
during an injury.
It is very serious because the bone may grow
crooked thereafter. May need repeated surgeries to
straighten the bone as it grows.
TRANSVERSE FRACTURE
• Bone breaks
completely through,
right to left, in the
transverse plane
OBLIQUE FRACTURE
• Bone breaks
completely through,
from upper to lower,
in an oblique plane
SPIRAL
FRACTURE: Bone
was twisted, such
as in skiing or
rollerblading.
COMMINUTED:
The most serious; bone
shatters into many small
pieces. Bone graft might
be needed.
AVULSION FRACTURE
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A piece of bone is broken off by the sudden,
strong contraction of muscle.
Common sports injury
Often seen with “groin muscle injury”
Avulsion
Fracture
The person twisted
their ankle and a
tendon pulled off a
piece of the bone.
IMPACTED FRACTURE
IMPACTED FRACTURE:
Pressure was exerted on both ends of the SAME
bone.
The bone is crushed
Often seen in femur after falling from a height.
Impacted
fracture of the
femur
• The person fell
from a height,
and the head of
the femur
jammed into the
neck of the
femur.
COMPRESSION FRACTURE
COMPRESSION FRACTURE
TWO bones are forced together
Bone is crushed.
Example would be two vertebrae being crushed
together from a fall from a height.
People with osteoporosis (loss of bone minerals)
often get this type of fracture spontaneously.
Table 6.1
DEPRESSION FRACTURE
DEPRESSION FRACTURE
Bone is pressed inward
Often seen in skull fracture from blunt object
Depression Fracture
PATHOLOGICAL FRACTURES
PATHOLOGICAL FRACTURE:
When the bone breaks first, then the patient falls. This
is especially common in the hip bone of someone
with osteoporosis.
ARTHRITIS
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OSTEOARTHRITIS
RHEUMATOID ARTHRITIS
GOUTY ARTHRITIS (GOUT)
OSTEOARTHRITIS
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OSTEOARTHRITIS: more common the older you
get.
The articular cartilage begins to break down, and
bone spurs start to grow. The surface is no longer
smooth, and movement now causes pain.
It is also known as “wear and tear” arthritis.
This is the most common disorder of joints.
Can be mild to severe, needing joint replacement.
These people can actually predict the weather,
since the synovial fluid is under pressure. As air
pressure changes, fluid expands and hurts more.
Artificial Hip
Joint
RHEUMATOID ARTHRITIS
RHEUMATOID ARTHRITIS: not a disease of old age. It’s
an autoimmune disease where body attacks and
destroys the cartilage in synovial joints. It is not known
for spur formation, unlike osteoarthritis.
They swell and become unusable, causing knarled hands
and feet. Usually need joint replacements, but that will
only last about 15 years. First replacement in 60 years
old is ok, but in a 30 year old, eventually bone
degrades and can no longer take the stem of the
implant.
It does NOT make many bone spurs; it is degenerative in
nature.
Rheumatoid Arthritis
GOUTY ARTHRITIS (GOUT)
Gout is caused by a genetic error in the metabolism of uric
acid. An gouty episode is triggered by eating too much
red meat or protein.
The breakdown product of proteins is urea, which leads to
uric acid crystals in the cooler areas of the body,
especially the MPJ’s (metatarsal-phalangeal joints) of the
base of the big toes. The crystals poke the cartilage like
needles.
Gout is not known for spur formation, unlike osteoarthritis
Was more common years ago when people ate nothing but
meat. The crystals cause the joint to swell up.
OTHER BONE DISORDERS
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Osteomalacia (“malformed bones”) is a genetic
malformation of the bones. The epiphyseal plates
are particularly affected.
Rickets is a type of osteomalacia that is NOT
genetic; it is caused by lack of vitamin D. Like all
types of osteomalacia, rickets also particularly affect
the epiphyseal plates.
OTHER BONE DISORDERS
Osteomalacia (genetic)
Rickets (not genetic)
OTHER BONE
DISORDERS
Osteomyelitis
an infection of
bone.
is
OTHER BONE DISORDERS
•Achondroplasia
is a
genetic condition
where the bones
don’t develop
properly, especially
in the epiphyseal
plates, and causes a
type of dwarfism.
CHONDROMALACIA
•Means
a problem with
the shape of a cartilage
joint.
•Chondromalacia
patella is a condition in
which the patella rubs
on the femur in the
knee joint, becomes
scratched or deformed,
causing pain. Don’t get
this confused with
achondroplasia, which
is dwarfism!
OTHER BONE DISORDERS
Paget’s
disease is
more common in
older persons, and
may be related to a
viral infection.
It is characterized
by excessive bone
deposition.
Paget’s disease
OTHER BONE DISORDERS
•ANKYLOSING SPONDYLITIS: is a disorder in which vertebrae
bind strongly together to limit the flexibility of the spine.
OTHER JOINT DISORDERS
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Synovitis is inflammation of the synovial tissues. May
need cortisone injections.
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Arthroplasty is a surgical procedure to repair or
remodel a damaged joint.
Lyme disease is an inflammatory arthritis of the knee
joint, caused from a bacterial infection after a tic bite.
Polydactyly (Many digits)
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The extra digit is usually a small piece of soft tissue;
occasionally it contains bone without joints; rarely it may be a
complete, functioning digit.
The extra digit is most common on the ulnar (little finger) side of
the hand, less common on the radial (thumb) side, and very
rarely within the middle three digits.
These are respectively known as postaxial (little finger), preaxial
(thumb), and central (ring, middle, index fingers) polydactyly.
Polydactyly can occur by itself as an autosomal dominant
mutation in a single gene.
But, it usually is one feature of a syndrome of congenital
anomalies.
1 in every 500 live births
Polydactyly (Many digits)
Polydactyly (Many digits)
Born with
two thumbs!
Syndactyly (Fused digits)
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In fetal development, syndactyly is normal.
At about 16 weeks of gestation, an enzyme
dissolves the tissue between the fingers and toes,
and the webbing disappears.
In some fetuses, this process does not occur
completely between all fingers or toes and some
residual webbing remains.
Simple syndactyly can be full or partial, and is present at
birth (congenital).
Syndactyly (Fused digits)
Due to an abnormal gene.
Syndactyly can be simple or complex.
– In simple syndactyly, adjacent fingers or toes are joined by soft
tissue.
– In complex syndactyly, the bones are fused.
Syndactyly can be complete or incomplete.
– In complete syndactyly, the skin is joined all the way to the tip of
the finger
– In incomplete syndactyly, the skin is only joined part of the
distance to the fingertip.
Syndactyly (Fused digits)
Syndactyly (Fused digits)
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Complex syndactyly occurs as part of a
syndrome (such as Apert's syndrome) and
typically involves more digits.
Apert Syndrome is syndactyly with
malformations of the skull.
Apert syndrome
Syndactyly (Fused digits)
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Fenestrated syndactyly means the skin is
joined for most of the digit but in a proximal
area there is gap in the syndactyly with
normal skin.
This type of syndactyly is found in amniotic
band syndrome.
Amniotic band syndrome
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Congenital disorder caused by entrapment of
fetal parts (usually a limb or digits) in fibrous
amniotic bands while in utero.
Polysyndactyly
End of Lecture
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The rest of this PPT is not on the exam
There is a disc between each bone in the spine.
The nerves exit the bone to supply
all the parts of the body.
If you choke off a nerve by twisting the bone around it,
the bone starts to crush the nerve.
Just like a light with a dimmer switch;
if you turn the electrical current down,
the light won’t shine as brightly.
If you cut off some of the nerve supply to an organ,
the organ isn’t going to function as well.
The discs are made out of
something like jelly. As long
as your spine is aligned,
the jelly will stay in the center.
But if the spine
becomes twisted,
the jelly will get pushed
in the opposite direction,
and the shock absorption
will be lost.
TEARS IN THE DISC
If you lift a box while you
are standing and twisting,
that’s when you get
tears in the disc.
The fluid in the disc begins to
leak out the side of the disc.
Osteoarthritis
Also Known As:
“Wear and Tear” Arthritis
Or Degenerative Arthritis
Occurs when cartilage wears
away, leaving raw bone to rub
against raw bone.
PROPER DESK WORK STATION
Phone headset for handsfree use
Computer at eye level
and 18-25” away from
your face
Chair with good lumbar
support or
$10 lumbar pillow
Keyboard
pad
under your
Thewrists
front of the
chair
should drop off
Adjustable seat: Feet flat to
the floor