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SKELETAL SYSTEM
206 BONES MAKE UP THE HUMAN
SKELETON
2 TYPES OF BONE
1.
Compact bone- (hard, dense outer area)
densely packed matrix of salts and
collagen- nourishment provided to bone
cells by blood vessels that extend through
Haversian canals
2.
Spongy bone –not as densely packedcontain spaces that are filled with bloodcalled red marrow
Matrix is deposited in thin, bony plates
called spicules around the red marrow
2 skeletons

AXIAL SKELETON- used mostly for
protection- bones of the skull, vertebrae,
ribs and sternum

APPENDICULAR SKELETON-used mostly
for support and movement- bones of the
hip and legs, also the shoulder and arms
Bone tissue

OSTEON or
HAVERSIAN
SYSTEM- complete
ring consisting of
osteocytes,
lamallae and a
central Haversian
canal
BONE TISSUE
Bone-“osseous tissue”
“OSTEOCYTE” - Mature bone Cell located in
LACUNAE- a hollow cavity
 LAMELLAE- Lacunae are arranged in concentric
rings of calcium salts
 HAVERSIAN CANAL- (it consists of blood vessels
and nerves)one central “bullseye”
 CANALICULI- tiny squiggly lines “canals”
radiating outward from the central Haversian
Canal- to all the lacunae in the osteon. This is
how nourishment gets to each osteocyte.
Bone tissue

PERFORATING
“VOLKMANN’S”
CANALS- blood
vessels that travel
at right angles to
the direction of
the shaft go from
the exterior of the
bone to the
interior and reach
the Haversian
canals
4 TYPES OF BONES
1. LONG BONE- longer than
they are wide- have a
shaft with heads at both
ends- all the bones of the
limbs (femur, humerus,
ulna, etc)- made mostly
of COMPACT bone
4 TYPES OF BONES
2. SHORT BONEtypically cube
shaped- mostly
SPONGY bone- bones
of the wrist and
ankle, patella
4 TYPES OF BONES

3. FLAT BONE- thin,
flattened, and usually
curved – contain two
thin layers of compact
bone sandwiching a
layer of spongy bone-
4 TYPES OF BONES
4. IRREGULAR BONEbones that do not fit
any of the above
categories(vertebrae, hip
bones)
PARTS OF LONG BONE
EPIPHYSES- the ends of the long bonescomposed of a thin layer of compact bone
surrounding spongy boneDIAPHYSIS- the shaft of the bonecomposed of compact bone
PERIOSTEUM – connective tissue covering
of the shaft of the long bone that
nourishes the bone
ENDOSTEUM- inner lining of the bone
cavity
PARTS OF LONG BONE
YELLOW MARROW-found in the
MEDULLARY CAVITY- The cavity of the
shaft is primarily a storage area of fat.
 RED MARROW - found in the cavities of
spongy bone and the epiphyses of long
bones
 (found in long bones in infants)

PARTS OF LONG BONE
EPIPHYSEAL PLATE- flat plate of hyaline
cartilage seen in young, growing bone. Cause
the bone to grow length wise. This cartilage
plate gets replaces by bone at the end of
puberty and leaves only an EPIPHYSEAL LINE to
mark their previous location
 ARTICULAR CARTILAGE- hyaline cartilage that
covers the epiphyses- provides a smooth,
slippery surface for a joint.

Functions of BONE (5)
1.
2.
3.
4.
Support
Protection- (ex.- skull and ribcage)
Movement- attachment places for
muscles and used as levers
Storage1. Minerals- calcium and phosphorus
2. Fat- yellow bone marrow
Functions of BONE (5)
5. HEMATOPOIESIS- the formation of
blood cells (both RBC and WBC) occurs in
the red bone marrow
BONE MARKINGS
PROJECTIONS THAT
HELP FORM JOINTS
Head
Facet
Condyle
Ramus
BONE MARKINGS
PROJECTIONS FOR MUSCLE AND
LIGAMENT ATTACHMENT
Tuberosity
Trochanter
Tubercle
Process
Crest
Line
Spine
Epicondyle
DEPRESSIONS AND OPENINGS
FOR THE PASSAGE BLOOD VESSELS
AND NERVES
Meatus
Sinus
Fossa
Groove
Fissure
Foramen
AXIAL SKELETON
SKULL- is formed by two sets of bones.
CRANIUM BONES- 8 bones that enclose
the brain
FACIAL BONES- 15 bones of the face and
jaw
SUTURES- immovable joints between bones
Cranium
Cranium from superior view
Facial Bones from
MANDIBLE
FUSED VERTEBRAE
First 5- Form the
SACRUM
Last 4 – Form the
COCCYX or tailbone
VERTEBRAL COLUMN
33 SEPARATE BONES9 BONES WILL
EVENTUALLY FUSE
TOGETHER
24 non fused vertebrae
1ST 7 VERTEBRAECERVICAL (NECK)
Next 12 VERTEBRAETHORACIC (contains ribs)
Last 5 VERTEBRAELUMBAR ( lower back)
TYPICAL VERTEBRAE
BODY- large section for
weight bearing
VERTEBRAL FORAMENopening for spinal
cord
SPINOUS PROCESSsingle spine at the
posterior of the
vertebrae
TYPICAL VERTEBRAE
VERTEBRAL ARCH- the
whole loop around
the vertebral
foramen- (consists of
Lamina and Pedicle)
TRANSVERSE PROCESSlateral projections
from the vertebral
arch
TYPICAL VERTEBRAE
SUPERIOR ARTICULAR
PROCESS- where it
forms a joint with the
vertebrae above
INFERIOR ARTICULAR
PROCESS-where it
forms a joint with the
vertebrae below
CERVICAL VERTEBRAE
1st vertebrae- ATLAS- articulates with
occipital condyles- (atlas has no BODY)
- allows you to nod your head “YES”
2nd vertebrae- AXIS- has a large superior
process (ODONTOID PROCESS or DENS)
which acts as a pivot
- allows you to rotate your head “NO”
CERVICAL VERTEBRAE
THORACIC VERTEBRA
LUMBAR VERTEBRA
BONY THORAX
thoracic cage”
Includes 1.
2.
3.
around the lungs and heart.
thoracic vertebrae
ribs
sternum
RIBS- 12 pairs attach to the
thoracic vertebra
7 pairs of TRUE RIBS which attach directly
to the sternum by COSTAL CARTILAGE
5 pairs of FALSE RIBS- which attach
indirectly or not at all to the Sternum
1 pair of FLOATING RIBS- which are the last
set of false ribs which lack any attachment
to the sternum
STERNUM
STERNUM- flat bone that is attached to the
first 7 ribs. The result of the fusion of
three bones
1. MANUBRIUM (top)
2. BODY
(middle)
3. XIPHOID PROCESS (point on
bottom)
3 LANDMARKS OF THE STERNUM
1. JUGULAR NOTCH- concave upper
border of the manubrium
 2 STERNAL ANGLE- fusion of the
manubrium and the body. Meets at a
slight angle. Located at the second rib
and is a reference point
 3. XIPHISTERNAL JOINT- point where
the sternal body and xiphoid process fuselocated at the 9th thoracic vertebrae

SPINE CURVATURES
SCOLIOSIS- spine is out of alignment
longitudinally “S shaped”
KYPHOSIS- extreme curvature of thoracic
vertebrae “hunchback”
LORDOSIS- extreme curvature of lumbar
vertebrae
Problems
RICKETS- disease in children in which bones
fail to calcify. Rickets is typically due to
lack of calcium in the diet or lack of
vitamin D which is needed for bone
absorption
OSTEOPOROSIS- disease typically of older
women- where bone tissue breaks down
faster than new bone tissue is built up
TYPES OF FRACTURES
Common Types of Fractures

SIMPLE /CLOSED- fracture that does not
break the skin

COMPOUND / OPEN- fracture that breaks
through the skin
TYPES OF FRACTURES
Types of reductions
CLOSED REDUCTION- putting the bone
back in alignment without surgery
OPEN REDUCTION- surgery is needed to
hold the bones in place with pins / wires
Other Types of Fractures
COMMINUTED- bone breaks into many fragments.
Common in elderly (osteoporosis). Causes- car
crashes, major accidents
COMPRESSION- bone is crushed. Common in
elderly (osteoporosis) and Vertebrae. Usually
from falling from serious heights
DEPRESSED- bone broken inwards- Skull fracture
due to blunt force trauma
TYPES OF FRACTURES
Other Types of Fractures
IMPACTED- broken bone ends forced
against each other- Common in falls from
large heights
SPIRAL- ragged break occurs from excessive
twisting. Common sports injury
GREENSTICK- bone breaks incompletelycommon in children’s bones which are
more flexible
OSSIFICATION- the formation
of bone tissue (Pg 121)
OSSIFICATION- involves 2 typeslengthening and widening
OSTEOBLASTS- bone-forming cells -form
the bone matrix
OSTEOCLASTS- bone destroying cells break
down old bone
Widening
Osteoblasts in the periosteum add bone
tissue to the external surface of the bone
while OSTEOCLASTS break down bone
from the inner surface of the diaphysis
wall. (endosteum)
Lengthening-Epiphyseal plates account
lengthening.
1. New cartilage is formed continuously on
the external surface of the epiphyseal
plate
2 Internal surface of epiphyseal plate is
being broken down and turned to bony
matrix by osteoblasts.
3 When the osteoblasts catch up and turn
all the epiphyseal plate to bone- growth
stops.
REMODELING- bones are living and
constantly changing
Due to:
1. CALCIUM levels in the blood,
PARATHYROID HORMONE breaks down
bone when its needed for calcium in the
blood.
CALCITONIN- (made in the thyroid)
lowers calcium levels in the blood by
producing more bone (storage)
2. Stresses by muscle pull and gravity
determine where bone matrix is broken
down or formed (larger projections for
increased muscle mass)
OSSIFICATION- Page 121
In embryos, the skeleton is primarily made of HYALINE CARTILAGE
which acts as a model.
2. A Bony Matrix of OSTEOBLASTS made by the PERIOSTEUM,
completely surrounds the hyaline cartilage along the diaphysis.
“BONY COLLAR STAGE”
1.
3. PRIMARY OSSIFICATION- blood vessel penetrates to center of
diaphysis where osteoblasts turn hyaline cartilage to bone



4. SECONDARY OSSIFICATION- blood vessels penetrate epiphysis
where osteoblasts turn hyaline cartilage to spongy bone
5. Center of diaphysis (endosteum) is then eaten away by
osteoclasts creating the Medullary cavity.
(The hyaline cartilage is replaced by bone by the time you are a
young child except for Articular Cartilage (which will never turn to
bone) and the Epiphyseal plates)
4 EVENTS OF BONE REPAIR
1
HEMOTOMA- blood filled swelling, pain, heat
In the inflammation stage, hematoma and
hemorrhage formation results from the
disruption of periosteal and endosteal blood
vessels at the site of injury. The open ends of
these vessels undergo thrombosis.
Macrophages, leukocytes and other
inflammatory cells invade the area
4 EVENTS OF BONE REPAIR
2.
FIBROCARTILAGE CALLUS- form granulation tissue
around injury site
In the primary soft callus formation stage, the cells that are
stimulated to produce new vessels, fibroblasts,
intracellular material and supporting cells. They form
granulation tissue in the space between the fracture
fragments. After that, macrophages, giant cells and
other wandering cells arise in granulation tissue to
invade and remove it . This stage lasts for about 2
weeks and clinically corresponds to the time when
clinical union is established by fibrous or cartilaginous
tissue.
4 EVENTS OF BONE REPAIR
3.
BONY CALLUS- osteoblasts migrate to area to form
bone form cartilage callus
The mineralization of soft callus begins about 1 week later,
after the formation of new soft callus. Increased
oxygenation to increase stability of callus. The
formation is dependent on the relative stability of the
fracture fragments. The more motion there is at a
fracture site, the larger callus is needed to prevent this
motion . When stability and strength have been gained
across the fracture site, the patient may resume
limited activity. The creation and mineralization of
callus may take anything from 4 to 16 weeks and is a
quicker process in children and in spongy bone
(Crenshaw 1992).
4 EVENTS OF BONE REPAIR
4.
BONY CALLUS IS REMODELED in response to
mechanical stress and forms a permanent patch
The callus remodellation stage consists primarily of the
replacement of callus with packets of new bone..Local
vascular supply, oxygenation and pH all revert to
normal.. The callus between the ends of compact bone
is replaced by secondary osteons composed of lamellar
bone.. The bone then first produces osteoclasts that
remove a packet of pre-existing hard tissue and then
produce osteoblasts that replace it with a packet of
newly made bone. Complete replacement of callus
with functionally competent lamellar bone by
remodeling one to four years
TYPES OF JOINTS
(ARTICULATIONS)
Joints can be classified in two ways.
Functionally and structurally
FUNCTIONAL
1. SYNARTHROSES- immovable
2. AMPHIARTHROSES- slightly movable
3. DIARTHROSES- freely movable
STRUCTURAL CLASSIFICATIONS
1.
FIBROUS – connected by fibrous tissuesutures of the skull (synarthrotic)
2.
CARTILAGINOUS- connected by fibrocartilage
or hyaline cartilage-vertebrae- Pubic
symphysis- (usually AMPHIARTHROTIC
3. SYNOVIAL- joints with a cavity containing
synovial fluid (DIARTHROTIC)
4 features of synovial joints
1.
2.
3.
4.
ARTICULAR CARTILAGE-(hyaline
cartilage on end of bone)
FIBROUS ARTICULAR CAPSULE- fibrous
connective tissue lined with synovial
membranes encloses the joint
JOINT CAVITY- filled with synovial fluid
REINFORCING LIGAMENTS-
4 features of synovial joints
BURSA SACS- tiny sacs of lubricating fluidthat act like “ball bearings”
 (can become inflammed- BURSITIS often
called water on the knee)


TENDON SHEATH- bursa sac that wraps
around a tendon to protect it
Type of synovial joints

1. Ball and Socket – head of one bone fits into
cavity of another bone-such as the shoulder or
the hip and femur. (MULTIAXIAL)
 2. Hinge - one bone can hinge in a trough
shaped area of another bone-such as the elbow,
ankle, and phalanges (UNIAXIAL)
 3. Pivot – allows one bone to rotate around
another, such as the atlas and axis , also the
radius and ulna. (UNIAXIAL)
Type of synovial joints

4. Condyloid “knucklelike” – one egg shaped
surface fits into an oval concavity- allows
movement from side to side and up and down
but no rotation- such as the wrist between
radius and carpals, or knee (BIAXIAL)
 5. Saddle – each bone has a convex and
concave shape-such as the joint between carpal
and metacarpal of the thumbs. (BIAXIAL)
 6. Plane- gliding movement across each other,
carpals (NONAXIAL)