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6th Grade Notes/Skeletal System
The skeletal system is the body’s
living
framework.
It consists of living material embedded in a matrix of
material.
The skeletal system is made up of
bones
non-living
,
ligaments
, and
tendons
Cartilage
- is dense, fibrous, flexible
cartilage
.
connective
tissue.
Ligaments
together.
- are connective tissue that holds
Tendons
to
muscles
- are connective tissues that attach
bones
.
The adult skeleton consists of approximately
206
There are 5 functions of the skeletal system. They are:
Provide
shape
Allow
movement
and
support
Protects
tissues and organs
Stores
certain materials
Produces
bones
blood
cells
bones.
,
Development of bones:
Many bones are formed from
cartilage
It is a stiff, jellylike material that is strong enough to provide support
but flexible enough to
bend
and
In newborns, many bones are almost all
twist
cartilage
,
.
.
The process of replacing cartilage with bone begins….
…about 7 months before birth
The process continues until the age of
25
.
In some places, the cartilage remains unchanged. For instance, places where
bone
meets
knee
,
bone
ankle
. For example, at the
, or
elbow
.
Two jobs cartilage has are to
cushion
bones against
sudden jolts, and provide a
slippery
surface
for bones to move on without
rubbing
against
each
other.
Bone Growth:
Bone growth takes place….
at both ends of long bones.
The growth region is called the growth plate or
Epiphyseal
Plate. It is in this region that
is taking place. The term
mitosis
for the process of cartilage being replaced by bone is
ossification
.
Structure of Bones:
Bones are one of the
toughest
yet
materials in your body, yet they make up barely
mass. Bones consist of
living
non-living
of your body’s
Osteocytes
living cells embedded in a network of tough
made up of
14%
material embedded in a matrix of
material.
collagen
lightest
are the
protein
fibers called
. The non-living part of the bone contains compounds
calcium
and
phosphorous
that
surround the osteocytes and make bone hard. Bones are covered with a living
layer called the
periosteum
muscles. It also provides a rich
which helps to connect them to
blood
supply to nourish the
bone. The middle portion of a typical long bone is called the shaft
The shaft contains the
filled with
central
yellow
cavity
marrow
yellow marrow is to store
fat
by a hard, bony material called
compact
.
which is
. The job of the
. The central cavity is surrounded
bone
.
There are small channels that run through the compact bone and contain
Blood
vessels
that nourish the
osteocytes
.
The shaft is separated from the ends of the bone by a line that marks the area
where
growth
formerly took place. This is called the
Epiphyseal
line
. In flat bones and ends of
long bones, the hard material is very thin. Underneath the hard material is the
spongy
bone
and the potential to
injury
. This reduces
red
and
,
during periods of physical activity.
In some bones, the spongy material contains
in which
shock
red
white
marrow
blood
,
cells
are produced.
Classification of Bones:
Bones are classified according to their
bones, such as the arms
and
and are involved in
movement
as the
underlying
and
skull
organs. The short
provide great
irregular
shape
legs
, support
bones, such as the
bones, such as the
weight
. The flat
sternum
flexibility
. The LONG
and
,
protect
wrist
and
precise
ribs
bones, such
ankles
,
movements. The
and
scapula
,
are adaptations that provide for specific needs involving
protection
, and/or
articulation
The adult skeleton consists of approximately
into two main divisions: the
appendicular
framework of
support
.
206
bones. It is divided
axial
skeleton and the
skeleton. The axial skeleton is the
support
bones including the
and
,
protection
skull , facial bones,
central
. It consists of 80
vertebral
column, and
rib
cage . The function of the axial skeleton includes: the skull
protects
the brain; the vertebral column holds the body upright
and protects the
spinal
cord
. The rib cage consists of 12
pairs of ribs and the sternum. Each rib is attached to the vertebral column. There
are only 7 pairs of “true” ribs – they are attached to the
cartilage
sternumb
by
. The other 5 pair of “false” ribs do not attach to the
sternum. The function of the rib cage is to protect organs of the
thoracic
cavity. The appendicular skeleton consists of 126 bones in the
pectoral
girdle, the
.
and
pelvic
girdle, and the
arms
legs
The function of the appendicular skeleton includes: the pectoral girdle provides
support for the
movement.
The
arms
and provides for their broad range of
Muscles
Attach the pectoral girdle to the axial skeleton.
pelvic
girdle attaches directly to the lower part of the
vertebral
column
.
Skeletal Joints:
Any place where two bones come close together is called a joint
.
Its job is to keep bones far enough apart so they don’t rub against each other.
There are six kinds of joints including pivot, ball-and socket, hinge, saddle,
gliding, and Ellipsoid. Pivot joints allow for
rotation
of one bone around
another. An example of a pivot joint is the
head/neck
. Ball-and-socket
joints provide for
motion
. An example of a
circular
ball-and-socket joint is the
in
one
shoulder
. A hinge joint allows movement
direction only. An example of a hinge joint is the elbow
A gliding joint allows for
precise
of a gliding joint is the
wrist
movements . An example
.
Injuries to the Skeleton:
Sprain
.
- when ligaments get torn or pulled beyond their normal
stretching range.
Fracture
- a break in a bone.
Dislocation
- when a bone is forced out of its joint.