The Skeletal System
• Bone is a tissue, a living material made up
of cells, and is it full of capillaries. The
skeletal system is made up of bones
which are connected to each other by
joints. Almost all bones have at least one
joint. Muscles are fibres that have the
ability to contract so that we can move our
bodies and internal organs. All these
elements make up the musculoskeletal
system whose function it is to allow us to
perform movement.
• How many bones are there in the human
skeleton?
• How many bones in
a newborn’s skeleton?
• Why the difference?
• How many bones are there in the human
skeleton? 206
• How many bones in
a newborn’s skeleton?
270
• Why the difference?
During development,
your bones fuse
together
Where are your organs in
relation to your skeletal system?
Where are your organs in relation
to your skeletal system?
• Your brain is covered by your cranium
• Your heart, lungs, kidneys, liver, etc are
protected by the rib cage, sternum,
vertebrae.
Take a look at the skeleton, and
the images of the x-rays and
diagram. What do you think are
the 5 functions of the skeletal
system?
The Skeletal System
Function
– forms an internal, living framework that
• provides shape and support
• protects internal organs
• moves body
• forms blood cells
• stores calcium and phosphorous
compounds for later use
4 types of bones based on shape
Type of bone Example in body
Main Function in body
Long Bones
Femur, humerus.
work with muscles to move
body parts, storage, support,
blood production.
Short bones
Tarsals, carpals,
clavicle
work with muscles to move
body parts, storage
Flat bones
Sternum, cranium,
scapula
Protect organs, blood
production
Irregular
Bones
The vertebrae,
mandible, Iliac.
Support, blood production,
movement
General Structure of the Human Body
A. 3 Anatomical regions of the body:
1. Head
2. Trunk
3. Limbs
1. The head
a. Skull (cranium)
– Houses the brain
– Cranial bones are flat and are immovable
b. Face
– All bones are immovable, except the jaw
(mandible)
2. Trunk (2 main groups of bones)
1. Spinal column
•
•
•
33 vertebrae (short bones joined by cartilage
which allow only limited movements)
It is flexible, mobile and resists shocks
5 parts
– Cervical (neck)
– Thoracic (chest)
– Lumbar
– Sacral (sacrum)
– Coccygeal (coccyx)
2. Trunk (2 main groups of bones)
2. Thorax or rib cage
– Ribs, sternum, thoracic vertebrae
– Make a bony cage that protects organs and
can change in volume for gas exchange
– 3 main types of ribs (continued next page)
3. Limbs
– Occur in pairs
– Each has 3 parts (i.e. arm, forearm, hand)
– They are jointed held together by ligaments
3 types of ribs
•
True ribs (first 7 pairs)
–
–
•
False ribs (next 3 pairs)
–
–
•
connected to the spine in back.
In the front, the true ribs are connected directly to
the breastbone or sternum by a strips of cartilage
slightly shorter than the true ribs and are connected
to the spine in back.
instead of being attached directly to the sternum in
front, the false ribs are attached to the lowest true
rib.
Floating ribs (last 2 pairs)
–
–
smaller than both the true ribs and the false ribs.
They are attached to the spine at the back, but are
not connected to anything in the front.
15
16
17
18
19
Bone
shape
1. Humerus
long
2.Radius
Long
3.Ulna
Long
4.Femur
Long
5.Fibula
Long
6.Tibia
Long
7.Cranium
Flat
8. Mandible
Irregular
9. Clavicle
Short
10.Scapula
Flat
11.Sternum
Flat
12. Rib cage
Long
13. Vertebrae
Irregular
14. Iliac bone (Pelvis)
Irregular
15.Carpals
Short
16.Phalanges
Long
17.Patella
Short
18.Tarsals
Short
19.Phalanges of the foot
long
Touch your
cranium
Touch
your pelvis
Touch
your
ribcage
Touch
your
patella
B. Characteristics of bones:
Made of layers of living tissue
- Diaphysis
– middle section of the bone
(yellow marrow)
– 2 Epiphyses
– ends of the bone (red marrow)
= red blood cells
– Periosteum
– Responsible for growth in width
– thin membrane that encloses
the bone
– role in growth of the thickness
of the bone, in healing
fractures. Continually active,
but decreases with age
Compact Bone
•
•
•
•
•
Directly under the periosteum
Hard, strong layer
Gives bones strength
Contains deposits of calcium phosphate
Contains bone cells and blood vessels
Spongy Bone
• Has many small, open spaces that make
bones lightweight
• Filled with a substance called marrow
– yellow marrow is composed of fat cells
– red marrow produces red blood cells
Cartilage
• Smooth, slippery, thick layer of tissue
• Covers the ends of bones
• Does not contain blood vessels or
minerals
• Flexible and acts as a shock absorber
• Makes movement easier by reducing
friction
Cartilage
C. Injuries
–
–
–
Fractures: broken bone, shortened limb, cracking
sound
Sprains: abnormal displacement with immediate
resetting, often accompanied by ligament tearing
Dislocation: displacement of joint, no cracking sound
D. Guidelines for healthy body structure
– Diet rich in Calcium and Phosphorus (from
food)
– Diet rich in Vitamin D (milk, sun)
– Vitamin A (promotes growth)
– Good Posture
– Normal functioning of specific glands
(pituitary gland or thyroid gland)
Joints
• Definition:
– Any place where two or more bones come
together
Joints
• Kept far enough apart by a thin layer of
cartilage so that they do not rub against
each other as they move
• Bones are held in place at joints by a
tough band of tissue called ligament
Types of Joints
• Immovable
– Skull
– Pelvis
• Moveable
– Pivot
– Ball & socket
– Hinge
– Gliding
Types of Joints
•Ball and Socket
Joint
•Bone with a
rounded end that
fits into a cuplike
cavity on another
bone
 ex: shoulder joint:
scapula to humerus
http://www.shockfamily.net/skeleton/JOINTS.HTML
Types of Joints
•Pivot Joint
•One bone
rotates in a ring
of another bone
that does not
move
ex: radius and
ulna
http://www.funhousefilms.com/b-pivot2.jpg
ex: neck joint
Types of Joints
•Hinge Joint
•Back-andforth
movement like
hinges on a
door
http://www.shockfamily.net/skeleton/JOINTS.HTML
 ex: elbow joint
(humerus into
radius)
Type of Joints
•Gliding Joint
•One part of
a bone
slides over
another
bone
http://www.shockfamily.net/skeleton/JOINTS.HTML
 ex: carpals
into
metacarpals
Review Questions- Answers
1)
What are the main functions of the skeletal system?
• provides shape and support
• protects internal organs
• moves body
• forms blood cells
• stores calcium and phosphorous compounds for later use
2)
What is the only moveable bone in the head?
The mandible
How many vertebrae are there, and how many groups are these
subdivided into? What are the names of these subdivisions?
33 vertebrae divided into 5 groups:
- Cervical (neck)
– Thoracic (chest)
– Lumbar
– Sacral (sacrum)
– Coccygeal (coccyx)
3)
Review Questions- Answers
4) Which bones make up the thorax or rib cage?
the ribs, sternum and thoracic vertebrae
5) What is the main difference between true ribs,
false ribs and floating ribs?
true ribs: attached to sternum via their own cartilage
false ribs: attached to sternum via shared cartilage
with the 7th true rib
floating ribs: do not attach to sternum
Review Questions
6) Describe the 3 living layers of bone.
Diaphysis:
middle section of the bone; where yellow marrow is produced
Epiphyses
ends of the bone; where red marrow is produced
Periosteum
thin membrane that encloses the bone
Responsible for growth in width of the bone
7) Compare and contrast compact bone and spongy bone
Compact Bone
•
Directly under the
periosteum
•
Hard, strong layer
•
Gives bones strength
•
Contains deposits of
calcium phosphate
•
Contains bone cells
and blood vessels
Spongy Bone
• Located under the compact
bone
• Has many small, open spaces
that make bones lightweight
• Filled with a substance called
marrow
Review Questions- Answers
8) What is cartilage and what is it’s function?
Cartilage is a smooth, slippery, thick layer of
tissue that covers the ends of bones. It acts
as a shock absorber and makes movement
easier by reducing friction
9) What is the difference between a sprain and
fracture and a dislocation?
Facture: breaking of bone
Sprain: stretching or tearing of ligament
Dislocation: bone popping out of socket
Review Questions- Answers
10) What would you recommend to a friend who was
always breaking their bones?
Eat a diet rich in calcium, phosphorus, vitamin A
and D and maintain good posture
11) What are the different types of joints and what are
some examples of each in your body?
Immovable joint: cranium
Moveable joints: ball and socket (shoulder), hinge
(elbow), pivot (neck), gliding (wrist)