Skeletal System
1-2 October 2015
Our bones are window to our
health, revealing secrets about
our lives past & current.
What do our bones reveal about us?
 Our health, past and current
 Trauma, past and current
 Age
 Gender
 Race
By the end of the mini unit,
you will know how our bones
change due to sex hormones,
age, and disease.
What are the functions of the bones?
1. Support - support and anchor the body and
organs
2. Protection – protect organs
Examples:
What are the functions of the bones?
1. Support
2. Protection
Examples:
 Skull protects brain.
Ribs protect heart and lungs.
Vertebrae protect spinal cord.
3. Movement – bones serve as an attachment site for
muscles; muscles use bones like levers for movement
4. Storage – fat, calcium, and phosphorus storage
5. Blood cell formation – Red and white blood cells
develop within the red marrow of long bones and flat
bones
What are the functions of the bones?
4. Storage – fat, calcium, and phosphorus storage
5. Blood cell formation – Red and white blood cells
develop within the red marrow of long bones and
flat bones
Classifying Bones by Shape
Sesamoid bones
are bones
embedded within
tendons. The
patella is the
largest example.
Sesamoid bones
are a type of short
bone.
Fun fact: The
number and size of
sesamoid bones
vary in different
people.
Classifying Bones by Shape
4 corners
Determine which
type of bone you
have & move to
the appropriate
corner of the
room.
Classifying Bones by Shape
4 corners
Examine all the
bones in your
group.
1. Do you all
agree about
the type?
2. Can you guess
which bones
any of them
are?
Structure of a Long Bone

The diaphysis is the shaft.

The epiphyses are the ends

Epiphyseal plates are plates
of hyaline cartilage found
near the ends of growing
bones. In adults, this
cartilage is completely
replaced by bone, forming
the epiphyseal line.
 The epiphyses are covered
with articular cartilage –
provides a smooth, surface
for joints.
Structure of a Long Bone

The diaphysis is covered with the
periosteum, a fibrous connective
tissue
 Inside the diaphysis is the
medullary cavity.
 In adults, the medullary cavity
is filled with yellow marrow
(function: to store fats)
 In infants, the medullary
cavity is filled with red marrow
(function: to produce blood)
 Fun fact: In adults, the yellow
marrow of the medullary
cavity can convert to red
marrow in cases of severe
anemia.
Structure of a Long Bone
Think, Pair, Share:
Name two ways the structure of
the long bone varies by age.
1) Infants have red marrow in
medullary cavity – converts
to yellow in adults
2) Growing individuals have
epiphyseal plates (cartilage);
adults have epiphyseal lines
Classifying Bones by Tissue Type
There are two types of bone tissue: spongy bone and
compact bone.
Classifying Bones by Tissue Type
There are two types of bone tissue: spongy bone and
compact bone.
Most bones contain both tissues types, in different
locations.
In irregular, flat, and
short bones, the
compact bone is
exterior and the
spongy bone is
interior.
Classifying Bones by Tissue Type
There are two types of bone tissue: spongy bone and
compact bone.
Most bones contain both tissues types, in different
locations.
Long bones are
mostly compact; in
long bones the
spongy tissue is
found only in the
ephiphyses (ends) of
the bones.
Microscopic Structure: Compact Bone
 Even compact
bone is not
solid! It has
many, many
channels for
blood vessels,
nerves,
nutrients and
wastes.
Microscopic Structure: Compact Bone
Basic unit of
structure: Osteon
 Consists of a
central
(Haversian)
canal and
lamellae (rings
of calcium salts)
 Between
lamellae are
cavities called
lacunae. The
osteocytes
(mature bone
cells) are found
in the lacunae.
Microscopic Structure: Compact Bone
Transport system:
 Blood vessels
and nerves grow
through central
canals (long
axis) and
perforating
canals (short
axis)
 Canaliculi (tiny
channels)
branch from
central canals to
all lacunae
Microscopic Structure: Compact Bone
Think, Pair,
Share:
Explain why an
excellent
transport system
is vital to the
functioning of
bone.
Microscopic Structure: Compact Bone
Microscopic Structure: Compact Bone
Microscopic Structure: Compact Bone
Osteon
lamellae
Microscopic Structure: Spongy Bone
All you need to
know is that
1) Spongy bone is
much less dense
2) Spongy bone
contains red
marrow, which
functions to
produce blood.
Bones of the skeletal system
Which ones do you need to know?
 Diagram 5.6 (page 125)
 Diagram 5.7 (page 126)
 Diagram 5.11 (page 129)
 Diagram 5.14 (page 131)
 Diagram 5.19 (page 135)
 Diagram 5.23 (page 142)
Human Skeleton
Some hints for memory .. .
• Radius is thumb side; ulna
is pinky side
• Its tibia and fibula
• The cuff of your sleeve is
by your carpals. The
tarsals are in your foot.
Knowing the
major bones will
help you learn
the muscle
names!
Lateral view of human skull
Sutures are
immovable
fibrous joints that
connect the
bones of the
skull.
Processes are
projections that
act as sites for
muscle and
ligament
attachment.
A meatus is a
canal. External
auditory meatus
leads to the ear
drum.
Knowing the bones of the skull will help you
learn the lobes of the brain!
anterior view of human skull
Foramen are small openings
in bone for the passage of
nerves and blood vessels.
A ramus is an arm-like
projection of a bone that
helps form a joint.
The vertebral column
The vertebral column consists of
33 bones that protect the spinal
cord and bear the weight of the
body.
The vertebral column is divided
into different regions. The
regions have different curves and
different shapes to the vertebrae.
The individual cervical, thoracic,
and lumbar vertebrae are
separated by fibrocartilage pads
called intervertebral discs
A slipped (herniated) disc
occurs when an
intervertebral disc slides out
of place, pressing on a nerve
The bony thorax
What bone shape
is the sternum?
Flat
Consists of ribs,
sternum, and
…thoracic
so what kind of
marrow
does it
vertebrae
have?
red
Sternum is three
bones fused
Intogether.
order to
diagnose certain
blood
disorders,
Has important
doctors
perform a
‘landmarks’
sternal
puncture
• Jugular
notch
by• inserting
a
Sternal angle
needle into the
sternum to obtain
red marrow.
The bony thorax
There are three
types of ribs.
True ribs connect
directly to the
sternum by a
cartilaginous joint.
False ribs
connect
indirectly to the
sternum (or not
at all). The last
two false ribs are
called ‘floating
ribs’ because
they do not
connect to the
sternum at all.
Pelvic Girdle
The pelvic girdle is
composed of two
hip bones, sacrum,
and coccyx.
Each hip bone is
composed of three
different bones:
• Ilium (most
lateral bone –
the ‘hips’)
• Pubis (most
anterior – these
fuse at a joint
called pubic
symphysis
• Ischium – most
inferior
Male vs Female Pelvic Girdle
Female pelvises…
• have a larger, more
circular inlet
• Is shallower / more
spread out
• Has a larger pubic arch
(80-85o)
Male pelvises…
• have a smaller, heart shaped
inlet
• Is deeper / more upright
• Has a smallerr pubic arch
(50-60o)
Thumbs up for girls!
Male!
• Pelvis is deep
• Inlet is heartshaped & narrow
• Pubic arch is 50-60
degrees
Thumbs up for girls!
Male!
• Inlet is heartshaped & narrow
• Pubic arch is 50-60
degrees
Thumbs up for girls!
Female!
• Inlet is large and
round
• Pubic arch is 80-85
degrees