1. Lesson Overview The Skeletal SystemLesson Overview The Skeletal System
•Who won the skeleton beauty contest? • No body
•What do skeletons say before they begin
•Bone appetit !
Why didn't the skeleton dance at the
•It had no body to dance with!
•What did the skeleton say while riding
his Harley Davidson motorcycle?
•I'm bone to be wild!
• Who was the most famous French
•What instrument do skeletons play? •Trom-BONE.
•Why couldn't the skeleton cross the
•He didn't have the guts.
•How did the skeleton know it
was going to rain ?
•He could feel it in his
•How do skeletons call their friends ?
•On the telebone !
•What do you call a skeleton who
won't get up in the mornings ?
•Why don't skeletons play music in
•They have no organs !
• What is a skeleton ?
•Somebody on a diet who forgot
to say "when" ! !
2. Lesson Overview The Skeletal SystemLesson Overview The Skeletal System
3. Lesson Overview The Skeletal System
4. Lesson Overview The Skeletal System
What are the functions of the skeletal system?
Support – rigid framework that maintains the shape of the body; supports the
organs suspended within it.
Protection – soft and delicate tissues and organs are protected by the skeleton.
Movement – muscles can attach to the bones.
Production of blood cells – red and white blood cells are made in the bone
Storage of minerals (and lipids) – calcium and phosphorus levels are maintained
by storing the excess in the bones.
5. Lesson Overview The Skeletal System
Parts of the skeletal system
Ligaments (bone to bone)(tendon=bone to muscle)
6. Lesson Overview The Skeletal System
Structure of the Skeleton
There are 206 bones in the adult human
22 bones in skull
6 in middle ears
1 hyoid bone
26 in vertebral column
25 in thoracic cage
4 in pectoral girdle
60 in upper limbs
60 in lower limbs
2 in pelvic girdle
Divided into axial skeleton and
7. Lesson Overview The Skeletal System
Structure of the Skeleton
The axial skeleton supports the
central axis of the body and consists
• Skull (cranium and facial bones)
– The cranium has a number of flat bones fitted together
at immovable joints.
• Vertebral column
– The backbone has 33 bones called vertebrae placed end
to end, each separated from the other by a cartilage disc.
• Ribcage and sternum
8. Lesson Overview The Skeletal System
Structure of the Skeleton
The bones of the arms and legs, along with the
bones of the pelvis and shoulder area, form the
• Arms and legs
– The upper part of the limbs consists of single long bones – the humerus in the
arm, and the femur in the leg.
– The lower part of the limbs has a pair of bones below the elbow or knee – the
radius and ulna in the arms, and the tibia and fibula in the legs.
• Pectoral and pelvic girdles
– The pectoral, or shoulder, girdle, consists of the clavicle (collar bone) and
scapula (shoulder blade). This girdle connects the humerus to the rest of the
– The pelvic girdle consists of two halves. These two hip bones (sacrum,
coccyx) form a hollow cavity known as the pelvis. This girdle connects the
femur to the rest of the skeleton.
9. Lesson Overview The Skeletal System
• Made of layers of living tissue
• Covered with a tough, tight-fitting
membrane called the periosteum
10. Lesson Overview The Skeletal System
What is the structure of a typical human bone?
A bone is a solid network of living cells and protein fibers (collagen) that
are surrounded by deposits of calcium and magnesium salts .
which is mostly stored fat.
11. Lesson Overview The Skeletal System
Adults continually break down and
build up bone
Osteoclasts remove damaged cells
and release calcium into blood
Osteoblasts remove calcium from
blood and build a new matrix.
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• Directly under the periosteum
• Hard, strong layer
• Gives bones strength
• Contains deposits of calcium phosphate
• Contains bone cells and blood vessels
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• Located at the ends of long bones
• Has many small, open spaces that make
• Filled with a substance called marrow
– yellow composed of fat cells
– red produces red blood cells
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Classification of Bones on the Basis
*Longer than wide
*About same length as width
Thin and usually curved
Protect brain and thoracic
Small and round
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16. Lesson Overview The Skeletal System
Characteristics of cartilage
• Smooth ,glossy ,flexible thick layer of
• It doesn’t contain very many minerals
although it contains collagen
• Does not contain blood vessels
• Covers the ends of bones
• Spread loads, reduces friction, and
allows flexible movement, acts as a
17. Lesson Overview The Skeletal System
The Vertebral Column
33 Vertebrae separated by
The spine has a normal
Each vertebrae is given a
name according to its
The spinal cord runs
through an arch of bone
formed by the vertebrae
18. Lesson Overview The Skeletal System
19. Lesson Overview The Skeletal System
The Skull or Cranium
•The skull protects the brain, most of the organs of the senses and entrances to
respiratory and digestive systems.
The skull has 28 bones (14 belong to the face) join by immovable joints can’t
move at all.
They either interlock or overlap.
hinged to the skull
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The Hyoid Bone
The only bone that
does not articulate
with another bone
Serves as a
moveable base for
21. Lesson Overview The Skeletal System
Commonly called the rib cage
Protects the heart, lungs, and other organs of
the thoracic cavity
Encloses the thoracic cavity
Composed of twelve pairs of ribs and the
sternum (breast plate or bone)
22. Lesson Overview The Skeletal System
The classification of ribs:
1. True ribs – 1st 7 pairs that attach directly to the sternum by the
2. False ribs – inferior 5 pairs that connect indirectly (first 3 pairs)
to the sternum or do not attach at all to the sternum (last two pairs)
3. Floating ribs – the last two pairs of false ribs that are not
attached at all
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Bones of upper limb
Humerus (upper arm)
Carpals, metacarpals, phalanges
Bones of lower limb
Tarsals, metatarslas, phalanges
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How are bones connected together?
• By Ligaments:
A ligament is a tough band of white, fibrous, slightly
elastic tissue. This is an essential part of the skeletal
joints; binding the bone ends together to prevent
dislocation and excessive movement that might cause
breakage. Ligaments also support many internal organs;
including the uterus, the bladder, the liver, and the
• By Joints: constructed to both allow
movement and provide mechanical
27. Lesson Overview The Skeletal System
• Joints are where two, or more,
• They are divided up into three
types depending on how
freely the bones can move:
 slightly movable
 freely movable
• Joints contain connective
tissues that hold bones
• Joints permit bones to move
without damaging each other.
• If we did not have joints no
movement would occur.
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• Immovable: bones sutured together by
connective tissue: skull
• Slightly movable connected by
fibrocartilage or hyaline cartilage:
vertebrae, rib/sternum joint, pubic
• Freely movable – separated ligaments-
hold bones together
tendons- muscle to bone
lined by synovial membrane
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Types of Joints
A hinge joint allows extension
and retraction of an appendage. (Elbow,
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Ball and Socket-
A ball and socket joint
allows for radial movement in almost
any direction. They are found in the hips
and shoulders. (Hip, Shoulder)
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In a gliding or plane joint bones
slide past each other. Mid-carpal and mid-
tarsal joints are gliding joints. (Hands,
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Saddle- This type of joint occurs when the
touching surfaces of two bones have both
concave and convex regions with the
shapes of the two bones complementing
one other and allowing a wide range of
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• Pivot: Rounded or conical surfaces of one bone
fit into a ring of one or tendon allowing rotation.
An example is the joint between the axis and
atlas in the neck.
• The joint between the atlas and
• The joint between the radius
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Types of movement and examples (with muscles)
flexion- move lower leg toward upper
extension- straightening the leg
abduction- moving leg away from body
adduction- movong leg toward the body
rotation- around its axis
supination- rotation of arm to palm-up position
pronation- palm down
circumduction- swinging arms in circles
inversion- turning foot so sole is inward
eversion- sole is out
35. Lesson Overview The Skeletal System
Freely moveable joints Or Synovial joints.
• Outer sleeve is called the joint capsule.
– It holds bones together &
– It is an extension of the skin
or periosteum that covers
• A synovial membrane.
– Lines the capsule and oozes a
slippery liquid called synovial
• A joint cavity.
– A small gap between the
– Filled with synovial fluid.
– Lubricates the joint so the
joint moves more freely.
• A covering of smooth slippery cartilage at
the end of the bones.
– Stops the bones knocking
• Ligaments which hold the bones together.
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• Ligament• Tendon
• Join bone to bone (joint) and
hold joints in place.
• Its matrix contains yellow
• Elastic but tough
• Allows movement at the joint
• Connects muscle to bone
(normally one tendon to a
non-moving part and
another tendon to a
• Its matrix contains white
• Tough and do not stretch
• They don’t stretch when
the muscle contracts to
move the bone
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Diseases and Conditions
of the Skeletal System
* Bursitis Inflammation of the Bursa sac
*Tendonitis most common cause of tendonitis is overuse
of the tendons.
* Carpal Tunnel Syndrome: swelling or change in position of the
tissue within the carpal tunnel squeezes and irritates the median
nerve. It causes tingling and numbness of the thumb, index, and
the middle fingers
* Osteoporosis bones have lost minerals (especially calcium)
making them weak, brittle, and susceptible to fractures
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* Scoliosis abnormal curvature of the spine.
More girls than boys have severe scoliosis.
* Kyphosis spine may develop a hump
* Lordosis A curvature of the vertebrae in
the lower back area
*Rickets softening and weakening of
bones in children
*Acromegaly occurs when the body produces too much of the
hormones that control growth, tissues grow larger than
39. Lesson Overview The Skeletal System
• How many muscles are there in the human body?
– Answer: 640 Muscles
– The muscles make up about 40 % of the body mass.
• What is the longest muscle in the body?
– Answer: The Sartorius
– The Sartorius runs from the outside of the hip, down and across to the
inside of the knee. It twists and pulls the thigh outwards.
• What is the smallest muscle in the body? Would you like to see it?
– Answer: The Stapedius
– The Stapedius is located deep in the ear. It is only 5mm long and thinner
than cotton thread. It is involved in hearing.
• What is the biggest muscle in the body?
– Answer: The Gluteus Maximus
– The Gluteus Maximus is located in the buttock. It pulls the leg backwards
powerfully for walking and running.
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41. Lesson Overview The Skeletal System
Functions of the Muscles
• Heat production
• Maintenance of posture and muscle
• Protects the bones and internal
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–Voluntary – can be moved at will
–Involuntary – can’t be moved
–Striated – have stripes across the fiber
–Smooth – no striations
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Skeletal Muscle Smooth Muscle Cardiac Muscle
3 Types of Muscles
The 3 Types of Muscles
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• Fibers are thin and in layers
• No striations
• Single nuclei
• Contracts and fatigues slowly
Found in the
* circulatory system (Lining of the blood vessels)
Helps in the circulation of the blood
*digestive system (Esophagus, stomach, intestine)
*respiratory system Controls breathing
*urinary system (Urinary bladder) Controls
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• Cells are branched and
appear fused with one
• Has striations
• Each cell has a central
• Found ONLY in the heart
• Contractions of the heart muscles pump blood
throughout the body and account for the heartbeat.
• Healthy cardiac muscle NEVER fatigues  or else…
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 Fibers are long and cylindrical
(arranged in bundles)
 Has many nuclei
 Has striations
 Have alternating dark and light
• Attached to skeleton by tendons
• Causes movement of bones at the joints.
• And yes… they do fatigue
what substance forms causing muscle fatigue???
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Functions of Skeletal Muscle
• Movement – muscle move bones by
pulling not pushing.
– Antagonists – muscles and muscle groups
usually work in pairs
– example the biceps flex your arm and its
partner the triceps extend your arm. The two
muscles are antagonists, i.e. cause opposite
– when one contracts the other relaxes.
– Levators – muscle that raise a body part.
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49. Lesson Overview The Skeletal System
Functions of Skeletal Muscle
• Maintenance of posture or muscle tone
– We are able to maintain our body position because
of tonic contractions in our skeletal muscles. These
contractions don’t produce movement yet hold our
muscles in position.
• Heat production – contraction of muscles
produces most of the heat required to maintain
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Structure of Skeletal Muscle
• Composed of striated muscle cells
(=muscle fibers) and connective tissue.
– Most muscles attach to 2 bones that have
a moveable joint between them.
• The attachment to the bone that does
not move is the origin.
• The attachment to the bone that moves
is the insertion.
– Tendons anchor muscle firmly to bones.
Tendons are made of dense fibrous
– Ligaments connect bone to bone at a joint.
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Structure of Skeletal Muscle
• Contribution of the nervous system
impulses travel from
the frontal lobes
via motor nerves
to the muscle fibers
and cause them to
Sensation is a function of the
brain – impulses are
integrated in the parietal lobes
of the cerebrum (conscious
muscle sense) and in the
These activities promote
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53. Lesson Overview The Skeletal System
Structure of Skeletal Muscle
- Muscle cells are filled with 2 types of fine threadlike proteins
called myofilaments: myosin (thick) and actin (thin).
are arranged in the cells in small units called sarcomeres.
These structures slide past each other
causing the muscle cell to contract or
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– Electrical impulse
travels down a
motor neuron. It
to spread over
– The sarcomeres
shorten and the
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Movement of Muscles
• Origin: the attachment of
the muscle to the bone
that remains stationary
• Insertion: the attachment
of the muscle to the bone
• Belly: the fleshy part of
the muscle between the
tendons of origin and/or
56. Lesson Overview The Skeletal System
skeletal muscle actions
• Categories Actions
• Extensor Increases the angle at a joint
• Flexor Decreases the angle at a joint
• Abductor Moves limb away from midline of body
• Adductor Moves limb toward midline of body
• Levator Moves insertion upward
• Depressor Moves insertion downward
• Rotator Rotates a bone along its axis
• Sphincter Constricts an opening
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Skeletal muscles usually work in pairs. E.g. The biceps
and triceps muscles
attached to the
scapula at the
top and to the
radius at the
As they bring about opposite effects, the biceps and triceps are examples of
A small contraction of the muscle will produce a large movement at the end of the limb
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• After exercise =>HIGH LEVEL of O2 consumption
PERSISTS until the excess of LACTIC ACID is oxidized :
• Accumulation of Lactic acid causes
CRAMPS and MUSCULAR FATIGUE
Only in EXTREME
Volume of O2 needed to
complete oxidize the
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60. Lesson Overview The Skeletal System
Long-term benefits of exercise.
•increase in size of the muscles used,
•reduction of heart rate and increase in
•more enzymes made in the muscles,
•stronger ligaments and tendons,
•more flexibility at the joints,
•possibly loss of excess body fat,
•possibly reduced chance of premature heart attack
•Healthy body and mind.
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Injuries to JOINTS, MUSCLES and
• SPRAINS joint is forced beyond its normal
degree of movement ligament totally or
• STRAINS violent contraction of the muscle
some of the fibres are torn
• DISLOCATIONS bones at a joint become
displaced as a result of a violent movement.
Usually ligaments also damaged
• FRACTURES a bone is broken
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Stages in the Healing of a Bone
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There are about 60 muscles in the face.
Smiling is easier than
It takes 20 muscles to smile and over 40 to frown.
Smile and make someone happy.