Introduction to Biomechanics
ISE789
Dr. R. A. Wysk
Spring 2010
Musculoskeletal System
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Bones
Passive soft tissue
Muscles
Nerves
Functions of the skeleton
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Support and motion
Protect vital organs
Mineral storage
Hematopoiesis
A little bit of anatomy
• Major mechanical functions of the body
– Purpose(s)
• Medical related issues
– Injuries
– Treatments
• Engineering issues
– Replacement
Anatomy terms
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Superior - toward the head
Inferior - away from the head
Anterior - the front of the body or body part
Posterior - the back of the body or body part
Medial - toward the midline that divides left and
right
Lateral - to the side away from the midline
Proximal - closer to the torso
Distal - farther away from the torso
Anatomical position - standing erect, facing the
observer, arms are at the sides with palms facing
forward.
Sectioning
• Read Medical Terms doc
Basic types of bone tissue
• Cortical bone
– Compact bone
– Central shaft of long bone
• Cancellous/trabecular bone
Trabecular or spongy
metal
– Spongy bone
– Found inside ends of long bone and inside
vertebral bodies
The Human skeleton
• There are 206 bones in the human body that
make up our skeleton
– 80 bones in the axial skeleton
– 126 bones - appendicular skeleton
• 60 bones – upper limbs
• 60 bones – lower limbs
– 4 bones – pectoral girdle
– 2 bones – pelvic girdle
Groups of bones
• Long bones
– Long in one direction
– Ends are expanded and covered
– Femurs, tibias, fibulas, humeri, radii, ulnas, metacarpals,
metatarsals, phalanges, and clavicles
• Short bones
– Same dimensions in all directions
– Thin cordices; filled with trabecular bone
– The entire vertebral column, carpal bones, and tarsal bones.
• Flat bones
– Skull
– Pelvis
– The ribs, scapula, sternum, and ilium
The human skeleton
Bone components
Cortical Bone
Osteonal Bone
Joints of the Body
• Synovial Joints
– Large range of motion joint
– Cartilaginous joints
– Between the ribs and sternum
• Fibrocartilage pad
Between adjacent vertebral bodies
Joints
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Fibrous
Fibrous joints connect bones without allowing any movement. The bones of your
skull and pelvis are held together by fibrous joints. The union of the spinous
processes and vertebrae are fibrous joints.
Cartilaginous
Cartilaginous joints are joints in which the bones are attached by cartilage. These
joints allow for only a little movment, such as in the spine or ribs.
Synovial
Synovial joints allow for much more movement than cartilaginous joints. Cavaties
between bones in synovial joints are filled with synovial fluid. This fluid helps
lubricate and protect the bones. Bursa sacks contain* the synovial fluid.
Synovial Joints
• Synovial joints allow for much
more movement than
cartilaginous joints. Cavaties
between bones in synovial
joints are filled with synovial
fluid. This fluid helps lubricate
and protect the bones. Bursa
sacks contain* the synovial
fluid.
Ball and socket Joints
• A ball and socket joint
allows for radial
movment in almost any
direction. They are
found in the hips and
shoulders.
Ellipsoid Joints
• Similar to a ball and socket joint
-- allow the same type of
movement to a lesser
magnitude. The wrist is an
ellipsoid joint.
Saddle Joints
• A saddle joint allows
movement back and
forth and up and
down, but does not
allow for rotation
like a ball and socket
joint.
Pivot Joints
• Pivot joints allow rotation around an axis.
The neck and forearms have pivot joints.
In the neck the occipital bone spins over
the top of the axis. In the forearms the
radius and ulna twist around each other.
Gliding
• In a gliding or plane
joint bones slide
past each other.
Metacarpal and
metatarsal joints are
gliding joints
The knee
A bad joint?!?
• 30-50% of all sports injuries
• 0.2% of the general population per year for
knee ligament problems
• ACL and MCL are 90% of all sport injuries
• Women are 2-8 times greater risk
Long bone
Long bone cont’d
Coefficients of Friction
Joint /material
Coefficient of friction
Human knee
0.001 – 0.02
Human hip
0.01 – 0.04
Gold on gold
2.8
Steel on steel
0.6 – 0.8
Glass on glass
0.9
Ice on ice at 0oC
0.01 – 0.1
J. Charnley 1960
A. Unsworth 1975
Synovial Joints
• Ball and socket Joints
– Hip and shoulder
• Bicondylar Joints
– Knee joints
• Multiple bone joints
– Wrist and ankle joints