BONES

206 Bones are said
to be in the Human
Skeleton.
 Although the human
skeleton is initially
made up of
cartilages and
fibrous membranes
this is soon replaced
by bone.
Bones
Basic Structure, Types, and
Locations

When discussing the skeleton is it
essential to review over the types of
cartilages found in the body.
– Hyaline Cartilages
– Elastic Cartilages
– Fibrocartilages
Cartilage

Hyaline Cartilage- Provides support with
flexibility and resilience. Makes up the
following in the human skeleton
– 1. articular cartilage- covers the ends of most
bones
– 2. costal cartilage- connect ribs to sternum
– 3. respiratory cartilage – found in make up
larynx
– 4. nasal cartilage- which support the external
nose.
Cartilage

Elastic Cartilage- Very much like
hyaline cartilage but ALSO contains
more stretch elastic fibers and better
able to stand repeated bending.
– Makes up only 2 skeletal locations
– 1. external ear– 2. epiglottis- flap that covers the opening
to the larynx each time we swallow.
Cartilage

Fibrocartilages Cartilage- are highly
compressible and have great tensile
strength. It is in between hyaline and
elastic cartilages
– Found in sites that are subjected to both
heavy pressure and stretch.
– 1. Menisci- padlike cartilages of the knee
– 2. Disk between the vertebrae.
Cartilage


Always remember
bone and cartilage are
always distinct different
tissues.
Bone has a hard matrix
while cartilage has a
flexible matrix that can
accommodate mitosis.
Division of the Skeleton

Axial Skeletonconsists of the
bony and
cartilaginous
parts that support
and protect the
organs of the
head, neck and
trunk.

Appendicular
Skeletonconsists of the
bones of the
upper and lower
limbs and bones
that anchor the
limbs to the axial
skeleton.
Bone Structure
 Bones
differ in
size and
shape but
have similar
structure,
development,
and functions.
Bone Classification
Long Bones
Long
longitudinal
axes, and
expanded end.
 Ex: Forearm
and thigh bones.

Bone Classification
Short Bones

Cube like, with
lengths and widths
roughly equal .

Bones in the wrists
and ankles.
Bone Classification
Flat Bones

Plate like structure
with broad
surfaces
 Ex: Ribs,
scapulae, and
some bones of the
skull.
Bone Classification
Irregular Bones

Variety of shapes
and are usually
connected to
several other
bones.
 Ex: Vertebra, and
some facial bones.
Bone Classification
Bone Function




Bones shape, support,
and protect body
structures.
They also act as levers.
House tissue that
produces bone/blood
cells
Stores various inorganic
salts.
Bone Function


Support- all the softer
tissues of the body;
they literally hang from
the skeletal framework.
Protection- hard, bony
“boxes” protect the
delicate structures
within them. Example:
skull to brain

Movement- Muscles
are anchored firmly to
bones.
Bone Function

Mineral and Growth Factor StorageBone is a reservoir for minerals like calcium
and phosphate. It also stores important
growth factors.

Blood Cell Formation- Most blood formation
or hematopoiesis occurs in the marrow
cavities of certain bones.
Bone Structure
Because bones contain tissue they are
considered an organ
 They contain not only bone (osseous)
tissue but nervous tissue, connective
tissue, muscle tissue, and epithelial
tissue.

Bone Marking

Throughout the next month as you work with
this bones you will need to recognize these
markings during lab
 Bones are rarely smooth..they display
projections, depressions, and openings that
serve as sites of muscle, ligament, and
tendon attachment as joint surfaces or
conduits for blood vessels and nerves.
Bone Marking

Projections (bulges)
that grow outward
from the bone
surface includes
– Heads, trochanters,
spines, and others.
– These are just a few
a complete list is on
pg 179
Bone Marking

Bone depressions
and opening include
– Fossae, sinuses,
foramina, and
grooves
– These are just a few
a complete list is on
pg 179
Bone Texture
When discussing bone texture the
outward appearance has a smooth solid
look to the naked eye and is referred to
as Compact Bone
 The internal layer is referred to as
Spongy Bone and looks like a
honeycomb.
 We will discuss this in more detail later.

Structure of a Long Bone

Diaphysis- Shaft of the bone, located
between epiphysis. A hollow tube made of
hard compact bone, hence a rigid and strong
structure light enough in weight to permit
easy movement.
 It surrounds a central medullary
cavity…”Marrow cavity”
 In adults the medullary cavity contains fat
(yellow marrow) and is called yellow bone
marrow cavity.
Structure of a Long Bone



EpiphysisThe outer ends (joints) of a long bone.
The exterior of epiphysis is compact bone
while the interior of epiphysis is spongy bone.
 Outer portion of the epiphysis is coated with a
layer of hyaline cartilage called Articular
Cartilage. Functions like a small rubber
cushion .
 Red bone marrow fills in small spaces in the
spongy bone composing the epiphyses.
Structure of a Long Bone
Epiphysis
 Between the epiphysis and diaphysis of
an adult long bone is an epiphyseal line
and remnant of the epiphyseal plate.
 The epiphyseal plate is a disc of
hyaline cartilage that grows during
childhood to lengthen the bone.

Structure of a Long Bone
Structure of a Long Bone

Another structure in all long bones are
membranes
– Peristeum- a strong fibrous membrane
covering a long bone except at joint
surfaces, where it is covered by articular
cartilage.
– A thin membrane containing bone-forming
cells called Endosteum lines the internal
bone surfaces.
Structure of a Long Bone

2 Types of Bone
Compact Bone- Wall of the diaphysis is
mainly composed of this. Hard and
dense; continues matrix with no gaps.
 Spongy Bone- Found on the ends of
the epiphysis…consists of many
branching bony plates. Contains
spaces that may be filled with marrow.
The needle-like threads of spongy bone
that surround a network of spaces are
called trabeculae.

Microscopic- Anatomy of Bone

In Compact Bone
 The rings are called
the matrix is
a concentric
organized into
lamella.
numerous structural
units called osteons
or Haversian
systems. Each
circular and tube like
osteon is composed
of calcified matrix.
Parts of the Long Bond
 Draw
and label
the long bone
on pg. 180 in
book.

http://www.mhhe.co
m/biosci/ap/holeess
entials/student/olc/m
atching0160.html

http://kidshealth.org/
kid/body/bones_SW.
html
Bone Development
Ossification and Osteogenesis are
synonyms meaning the process of bone
formation.
 In embryos this process leads to the
formation of the bony skeleton
 And continues on until early adulthood
as the body continues to grow in size.

Bone Development
Bone Development

The first 8 weeks of development the human
embryo is completely fibrous membranes and
cartilage
 Bones continue to grow and develop into
adulthood.
 Bones form by replacing existing connective
tissue in one of two ways
 Intramembranous Bones and Endochondral
Bones
INTRAMEMBRANOUS
BONES





When a bone develops from a fibrous membrane it is
called intramembranous ossification and the bone is
called a membrane bone.
Intramembranous ossification results in the formation
of Flat Bones (Mostly of the skull and clavical).
During development membrane like layers of
connective tissues appear at the area of future
bones.
Layers supplied with blood vessels and tissue
arranged around the vessels
Cells enlarge and change into bone-forming tissue
called OSTEOBLAST.
ENDOCHONDRAL BONES





Ex: Most all bones
They develop as hyaline cartilage that is later
replaced by bone tissue.
This is more complex than intramembranous
ossification because the hyaline cartilage must be
broken down as ossification proceeds
Primary ossification centers appears in the diaphysis,
whereas secondary ossification centers appear in the
epiphyses
An epiphyseal plate remains between the primary
and secondary ossification centers. Development
proceeds from masses
Osteo….The different types
bone cells.
Osteoblasts - make new bone and
help repair damage;
 Osteocytes- mature bone cells.carry
nutrients and waste products to and
from blood vessels in the bone;
 Osteoclasts- break down,reabsorb
bone and help to sculpt and shape it.
Osteoclasts are very active in kids and
teens, working on bone as it is
remodeled during growth. They also
play an important role in the repair of
fractures.

Bone Growth- Epiphyseal Plate

An epiphyseal plate
consists of layers of
cells: resting cells,
young cells, older
enlarging cells and
dying cells.

The epiphyseal
plates are
responsible for
lengthening.
 Long bones
continue to lengthen
until the epiphyseal
plates are ossified.
Bone Growth- Epiphyseal Plate
 Growth
in
 The action of
thickness is due
osteoclasts
to
forms the
intramembrano
medullary
us ossification
cavity.
beneath the
periosteum.
HOMEOSTASIS OF BONE
TISSUE

Osteoclast and osteoblast continually
remodel bone.
 The total mass of bone remains nearly
constant throughout life. While it may appear
to be lifeless it is VERY active
 Adult skeleton normally recycles 5-7% of our
bone mass a week…spongy bone replaced
every 3-4 years, compact bone every 10.
Factor Affecting Bone
Development

Sunlight, hormonal
secretions, and
exercise all affect
bone development
 Deficiencies of
vitamin A,C, or D
result in abnormal
development.

Physical stress
 Exercise thickens
and strengthens
bone tissue
 Lack of activity can
cause waste and
thin tissue.
BONE- Blood Cell Formation
 Hemopoiesis-
the process of blood
formation.
 Begins in the yolk, which lies
outside the embryo. Later in
development, blood cells are
manufactured in the liver, spleen,
and still later they form in the bone
marrow.
BONE- Blood Cell Formation
Marrow-
soft tissue within
the medullary cavity of long
bones, in spongy bone, and
in canals of compact bone
tissue.
MARROW


RED MARROWFunctions in the
formation of red blood
cells, white b.c’s and
blood platelets
Occupies most cavities
of infant bones, later
replaced by yellow
marrow.
•
•
•
•
Yellow Marrow
Stores fat
Inactive in blood cell
production.
By adolescence, most of
our marrow is yellow
Red blood cells only live
about 120 days, they
are replaced or
recycled.

Blood cell
production in
ADULTS routinely
occurs in the
heads of the
_femur_ and
humerous_.

If you were to
obtaining red
marrow samples
from the body.
Some of the best
places to go would
be the Sternum
and hip bones.
Hematopoiesis are
very active here
Inorganic Salt Storage

The intercellular
matrix of bone
tissue contains
collagen and
inorganic mineral
salts.

The crystals that are
formed are a type of
CALCIUM
phosphate.
The need for Calcium
 Our
body requires calcium for a
number of vital metabolic
processes;
 Blood clot formation.
 Nerve impulse conduction.
 Muscles cell contractions.
The need for Calcium
 When
the blood is low in calcium,
parathyroid hormone stimulates
osteoclasts to break down bone
tissue, releasing calcium salts from
the intercellular matrix into the
blood.
Osteomalacia

Osteomalacia- includes a number of
disorders in which the bones are
inadequately mineralized. Two examples of
this included..
 Rickets – is just osteomalcia that is seen in
young children
Rickets





Rickets is a softening of bones in children due to deficiency or
impaired metabolism of vitamin D, phosphorus, or calcium
Potentially leading to fractures and deformity.
Rickets is among the most frequent childhood diseases in many
developing countries.
The predominant cause is a Vitamin D deficiency, but lack of
adequate calcium in the diet may also lead to rickets (cases of
severe diarrhea and vomiting may be the cause of the
deficiency).
Although it can occur in adults, the majority of cases occur in
children suffering from severe malnutrition, usually resulting
from famine or starvation during the early stages of childhood.
Rickets
Osteoporosis
Osteoporosis- refers to a disease in
which bone resorption outpaces bone
deposits.
 Bones become fragile and therefore
easily fractured. a condition that results
from loss of bone minerals.

Osteoporosis
BONES

206 Bones are said
to be in the Human
Skeleton.
 This numbers varies
between people.
 Structural bones
may develop in the
area where the flat
bones of the skull
fuse.
Bone Repair

Despite remarkable strength, bones are
susceptible to fractures or break!
 Resulting from twists or smashing of bones.
 Excessive intake of vitamin A and elevated
blood levels of the protein homocysteine may
increase the risk as well as thin and weaken
bones that accompany age.
Bone Repair

Non-displaced
fractures- the bone
will retain their
normal position
 Displaced
Fractures- the
bones are out of
their normal position
Bone Repair

Complete Fracturethe bone is broken
in two; completely
through

Incomplete
Fracture -the bone
is not.
Bone Repair

Linear Break- the
break parallels the
long axis

Transverse Breakthe break is
perpendicular to the
bone’s long axis.
Bone Repair

Compound
Fracture- the bone
ends penetrate the
skin

Simple Fracturethe bone does NOT
penetrate the skin.
Axial Skeleton
Skull
 Hyoid bone
 Vertebral column (which includes
sacrum and coccyx)
 Thoracic cage (which includes ribs
and sternum)

Appendicular Skeleton
Pectoral girdle (scapula, clavicle)
 Upper limbs (humerus, radius, ulna,
carpals, metacarpals, phalanges)
 Pelvic girdle (as coxae, pelvis)
 Lower limbs (femur, tibia, fibula,
patella, tarsals, metatarsals,
phalanges)
