bones Flashcards
bone vascularization
highly vascularized
how many bone are there in the human skeletal
206
126 app
80 axial
cells of bones
osteo - cytes, blast, clast
osteoid
part of the ECM that is not calcified yet
ECM in bone
fiborous organic matrix permitted by inorganic salts
Osteocyte
mature bone cells, and are the adult version of osteoblasts.
- Osteoblasts
make bone tissue
- Osteoclasts
cells that break down bone matrix
necessary for bone maturation and bone healing
remove bone that we do not need
where do we see bones cells
embedded in the ECM
periosteum
the membrane of blood vessels and nerves that wraps around most of your bones
is the periosteum everywhere on the bone
no not on the articular surface of the bone
periosteum in young bone
thick and vascularized
what happens to the bone if it loses periosteum
subject to necrosis
types of bone
compact/cortical
trabecular/spongy/cancellous
- Cortical/compact bone force
resisting torsional, or rotational stress
- Cortical/compact bone local
surrounds spongy bone
Haversian system
functional unit of the compact bone
Haversian canal surrounded by concentric layers of compact bone tissue called lamellae
Metabolically active; the osteoblasts and osteoclasts are active
- Trabecular bone other names
spongy
cancellous
Trabecular bone force
compressive forces
Trabecular bone
the interior of mature bone
less dense than cortical bone
weaker than cortical bone
Highly vascular
Often contains bone marrow
How is spongy bone laid down in response to stress
disposed on line of stress of greatest compression - wolfs law
What happens if there is Decreased stress on the bone
bone will become weaker and lose density.
What is the response to stress does spongy or cortical bone change more
Primary change occurs in the trabecular bone.
Cortical bone can also remodel and become thicker
A reduction in bone density is called
Osteopenia
more force =
more bone
less force =
less bone
Principal compressive group in the femur
Supporting Bundle
From head of femur to inf neck
Secondary compressive group
Trochanteric Bundle
From lesser to greater trochanter
Principal tensile group
Arcuate Bundle
From inf greater trochanter to femoral head
Ward’s Triangle (Zone of Weakness):
area in the proximal femur that is particularly at risk for fracture
what do the proportions of cortical and trabecular bone depend on
The function of the bone
long bones
Thick cylinder of compact bone with few trabeculae lining inner surface
Expanded articular ends
femur
short bones
Small geometric shapes
trabecular bone covered by only a thin layer of compact bone – therefore, they’re well-suited to withstand compression
tarsals in the foot
flats bones
Thin compact layer surrounds inner layer of trabecular bone
Protective function
often play important roles in protecting other organs- the bones in in your cranium help protect the brain
Irregular Bones
Depending on their location and function, the proportion of trabecular to cortical bone varies
Thick trabecular bone where compression forces are greatest
Thick compact bone where torsional forces are greatest
vertebrae in your spine - Compression forces are very strong
Sesamoid Bones
Located within tendons - Housed entirely within tendons
alter the line of pull of a muscle, to give it more mechanical advantage.
patella - lives within the tendon of the quadriceps muscle
Bony Prominences
Protuberances on surfaces of bone
Site of mm attachment
Alters line of pull of mm
Endochondral ossification
Most bone develops according to the endochondral ossification method
hyaline cartilage –> bone as maturation occurs.
Intramembranous ossification
from condensed mesenchyme (connective tissue); direct ossification begins during the fetal period
when can osteogenesis begin
Early in prenatal life
Later in prenatal life
After birth
Short Bones are Ossified from where
a Single Center
usually in the middle of the bone
Ossification centers
areas from which new bone is formed
How many Ossification centers in most bones
Several Ossification Centers
Primary center of ossification
Located near middle of future bone with progressive ossification toward bone ends
Appears in late embryonic life or early fetal life
Secondary centers of ossification
Occur in cartilaginous ends of long bones
Develop from birth to late teens
May Be Multiple - femur has 2 secondary ossification centers, proximal and distal ends
What actually happens in ossification centers?
Osteoblasts synthesize collagen and proteoglycans
Collagen is extruded into extracellular space to form osteoid matrix which becomes calcified
Trabeculae thicken
2 types of bone growth
appositional
interstitial.
Appositional bone growth
new bone tissue is laid on top of already-existing bone
Interstitial bone growth:
how bones grow longer
Bone grows in length near cartilaginous growth plates
Important in growing children
Diaphysis
Shaft of bone
Develops from primary center of ossification
Diaphysis function
Mechanical support and housing of bone marrow
Epiphysis
Expanded end of bone
Layer of hyaline cart remains over joint surfaces
Epiphysis develops from where
2ndary center
Epiphysis function
to support joint movement
Epiphyseal Plate
epiphyseal plate = growth plate
Bone increases in length until ossification (fusion) of this plate
Hyaline cartilage (p)
- As long as the growth plate remains composed of hyaline cartilage, the bone can continue to grow in length
Metaphysis
metabolically active regions of the bone- Here is where that increase in length actually occurs.
Apophysis
Bony projection that lacks 2ndary center of ossification
Attachment for ligaments or tendons
tibial tuberosity
Nutrition of Long Bones
Long bones receive nutrition from multiple sources
diaphysis, or shaft, has its own nutrient arteries
epiphyses and metaphyses receive their own separate nutrient arteries
diaphyseal nutrient aa goes through
transmitted thru nutrient foramina in diaphysis
where do Large irregular bones receive nutrition
superficial blood supply from periosteum and some nutrient arteries that penetrate trabecular bone
where do Vertebrae receive blood from
arteries that enter near base of transverse processes
where do Short and flat bones receive blood
receive blood supply from periosteum
innervation of bones
- Most bones are highly innervated. (That’s why it really hurts when you break a bone.)
risers sign
used to estimate How close growth plates are to closing, measured in the ilium
looking at skeleton maturity
when do most bones fuse
16 years old - teens
when does the Fusion of the ilium usually occurs
16 in boys and 14 in girls
what is a another indicator of bone maturity other then risers
vertebrae
ischial tuberosity fusion
Commencement of ossification - puberty
Fusion - 25 years (late)
femur ossification
Various ossification centers within the femur differ in when maturity starts to occur
femur complete the fusion process between 18-20 years
Fracture
Disruption in the continuity of bone
why are fracture painful
Periosteum is highly innervated.
Fractures cause edema (swelling) in surrounding tissues which can cause additional pain.
There is often painful involuntary spasm of surrounding muscles trying to hold the bone together.
Traumatic fracture
some type of injury or accident that disrupts the continuity of the bone
Pathologic fracture
is caused by some other pathology
a tumor in a bone will lead that bone to fracture - angles watching over me
Periprosthetic fracture
occurs in the area around surgery
EX: periprosthetic fractures in the proximal femur near where a hip replacement was performed
Stress fracture
tiny crack in a bone that’s often caused by repetitive overuse
open fracture another name
compound fracture
breaks through the skin.
Closed fracture another name
simple fracture
does not break through skin
displaced fracture
the two of ends of the bone moved and no longer line up.
displaced fracture healing
requires reduction, or a realignment of the two ends
Nondisplaced fracture
ends of the bones are still aligned
Incomplete fracture
Fracture line doesn’t go all the way through the bone
Complete fracture
goes all the way through
Comminuted fracture
pieces actually break off.
Osteoporosis
Pathological decrease in the density of the bone
Point to where the bone has holes in it - porous
Increases the risk of pathologic fractures.
Osteoporosis in Spine
osteoporosis often leads to a collapse of the vertebral body
Osteosarcoma
common type of bone cancer
Osteosarcoma age group
usually affects teenagers and young adults
Osteosarcoma location
Usually form at the ends of long bones, especially the femur, tibia, and humerus
blastic lesions
seen with Osteosarcoma
tumors fills the bone with extra cells - white X-ray
lytic lesions
seen with Osteosarcoma
The tumor causes the destruction of bone material
Multiple Myeloma
bone cancer, affects the plasma cells in bone marrow.
cancer cells “crowd out” the bone marrow cells
cancer cells signal the osteoclasts to break down bone at a high rate- bone is destroyed and not rebuilt
what are the consequences of Multiple myeloma
lacking bone marrow, body loses the ability to produce enough new blood cells.
This results in anemia, problems with the immune system, and kidney problems.
punched-out lesions
seen with Multiple myeloma
X-ray: It looks as though someone took a hole-puncher to the bones
