Senior MESA Day
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Overview of the Human Arm Anatomy
◦ Bones, Joints, Muscles
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Review Arm Motion
◦ Kinematics: types of motion, location of motion, direction
of motion, magnitude of motion, and degrees of freedom
◦ Kinetics: extrinsic forces, intrinsic forces, force vectors,
force of gravity, reaction forces, additional linear forces,
and classes of levers
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Overview of the Prosthetic Arm
Building the Model
Building the Display
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Humerus
◦ The longest and largest bone in the upper
extremity.
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Ulna
◦ A long bone in the forearm parallel with the radius;
at the proximal is the elbow and the distal end is
the wrist.
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Radius
◦ The other bone of the forearm, shorter than the
ulna.
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Carpals
◦ The wrist is composed of 8 separate carpal
bones.
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Metacarpals
◦ The intermediate part of the hand skeleton
that is between the carpals and the
phalanges (up to the knuckles); 5
metacarpal cylindrical bones
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Phalanges
◦ The fingers of the hand contain 14 digital
bones.
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Elbow Joint/Complex
◦ Humeroulnar Joint – simple hinge-joint
◦ Humeroradial Joint – arthrodial joint allowing
gliding and sliding motions
◦ Proximal Radioulnar Joint – pivot joint
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Wrist Joint
◦ Radiocarpal joint
◦ Carpometacarpal joints
◦ Intercarpal joints
intercarpal
joints
carpometac
arpal joint
midcarpal
joint
radiocarpal
joint
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Metacarpophalangeal Joints
Interphalangeal Joints
interphalangeal
joints
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Flexion: decreasing joint angle such as bending
Extension: increased joint angle such as stretching
Abduction: movement that draws limb away from sagittal
plane
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Adduction:
movement which brings limb closer to the
sagittal plane
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Supination: palm faces up
Pronation: palm faces down
Circumduction: combination of flexion, extension,
abduction and adduction
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Upper Arm
◦ Biceps brachii, brachialis, coracobrachialis
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Forearm
◦ Flexor-pronator and extensor-supinator
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Hand
◦ Thenar, hypothenar, interosseous, lumbrical
Arm Muscles and Their Functions
Anterior of forearm
Muscle
Biceps brachii
Location
Anterior Arm (humerus)
Function
Flexion and supination of the elbow
Brachialis
Anterior Arm (humerus)
Flexion of elbow in all positions, but
especially when the forearm is
pronated
Triceps brachii
Posterior Arm (humerus)
Extension of the elbow
Brachioradialis
Posterior/Anterior Forearm
(superficial)
Flexion of elbow; also pronation and
supination, depending on position of
forearm
Pronator teres
Anterior Forearm (superficial)
Pronator quadratus
Anterior Forearm (deep layer)
Pronation of forearm; flexion of the
elbow
Pronation of the forearm
Flexor carpi radialis
Anterior Forearm (superficial)
Flexion and abduction of the wrist
Palmaris longus
Anterior Forearm (superficial)
Flexion and abduction of the wrist
Flexor carpi ulnaris
Anterior Forearm (superficial)
Flexion and abduction of the wrist
Flexor digitorum superficialis
Anterior Forearm (superficial)
Flexion of the fingers
Flexor digitorum profundus
Anterior Forearm (deep layer)
Flexion of the fingers
Flexor pollicis longus
Anterior Forearm (deep layer)
Flexion of the thumb
Supinator
Extensor carpi radialis longus
Posterior Forearm (deep layer)
Posterior Forearm (superficial)
Supination of forearm and wrist
Extension and abduction of the wrist
Extensor carpi radialis brevis
Posterior Forearm (superficial)
Extension and abduction of the wrist
Extensor carpi ulnaris
Posterior Forearm (superficial)
Extension and adduction of the wrist
Extensor digitorum
Posterior Forearm (superficial)
Extension of the fingers
Extensor digiti minimi
Posterior Forearm (superficial)
Extension of the fingers
Extensor pollicis brevis
Posterior Forearm (deep layer)
Extension of the thumb
Extensor pollicis longus
Posterior Forearm (deep layer)
Extension of the thumb
Abductor pollicis longus
Posterior Forearm (deep layer)
Extension and abduction of the thumb
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Tough bands of fibrous connective tissue that
connects muscles to bones.
◦ Capable of withstanding tension
◦ Function to transmit force
◦ Function as springs
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Purpose: To understand and demonstrate the
bones, tendons and muscles of the hand
Materials per group:
10 straws
10 beads
10 popsicle sticks
string
Shared Tools:
Glue gun
Lesson plan courtesy of:
Curt Gabrielson
Watsonville Community
Science Workshop
Saw
Scissors
Tape
Bamboo skewers
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Cut a full length popsicle stick into 1/3 pieces
Cut 3 pieces of straw slightly shorter than sticks
Glue pieces of straw to stick pieces
Glue all three segments onto a full straw; leave a
small space in between each segment, so that
flexing is possible
Glue 3 segments with full straw end to a full length
stick
Glue one more straw segment onto the top of the
full length stick in line with other 3 segments
Tie a bead to the end of piece of string and thread
other end through all 4 short straw segments
Tie bead to other end. Wrap each segment with
tape.
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Cut a paint paddle in half, then one half into two
pieces, one about an inch shorter than the other
Glue the larger piece to the top of the full half to
form a “T”. Glue smaller piece right underneath it.
Make three more fingers and a thumb
Glue the fingers to the paint paddle frame
Glue on the thumb more towards the side of the
side of the hand
Each finger should move when pulling on its string
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Types of Motion
◦ Translatory: all parts move toward same direction
◦ Rotatory/Angular: around a fixed axis
◦ General: combination of translation and rotation
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Location of Motion
◦ Transverse or Horizontal Plane
 Superior and Inferior
◦ Coronal or Frontal Plane
 Anterior and Posterior
◦ Sagittal plane
 Medial and Lateral
Axis of rotation
Direction of motion
Perpendicular to
Sagittal axis
Horizontally from
front to back
Coronal plane
Coronal axis
Horizontally from side Sagittal plane
to side
Vertical axis
Perpendicular to
ground
(anterior posterior axis)
(frontal axis)
Transverse plane
y - vertical axis
x - coronal axis
z–
sagittal axis
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Magnitude of Translatory Motion
◦ Displacement: change of position
that an object moves from the
reference point
C
3.6 m
3m
2m
◦ Velocity: rate of change in
displacement
 v = dx / dt
◦ Acceleration: rate of change in
velocity over time
 A = dv / dt
B
A
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Magnitude of Rotatory Motion
◦ Angular displacement: rotation of an object about
an axis in radians
Δθ = Δθ2 − Δθ1
◦ Angular velocity: time rate at which an object
rotates about an axis, or at which angular
displacement between two bodies changes
◦ Angular acceleration: change of angular velocity
over time
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Degrees of Freedom
◦ 3 translatory motions along the x, y, and z axes and
3 rotatory motions around the x, y, and z axes
◦ 6 DOF of a rigid body
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Moving up and down
Moving left and right
Moving forward and backward
Tilting forward and backward (pitch)
Turning left and right (yaw)
Tilting side to side (roll)
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Purpose: to understand degrees of freedom
in biomechanics
Materials:
Standard coffee mug
Water
Bucket
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Fill standard coffee mug with water ¾ full
Place empty bucket on table. Using your hand,
grab and lift the cup and pour the water into the
bucket
◦ How many different positions can you pour the water
without spilling?
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Restricting a DOF at the shoulder joint, grab and
lift the cup and pour the water
Restricting a DOF at the elbow joint, grab and lift
the cup and pour the water
Restricting a DOF at the wrist joint, grab and lift
the cup and pour the water
Record observations on Activity Sheet (page 41 of
curriculum)
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Purpose: to build a paper robot arm and
demonstrate the degrees of freedom
Materials:
Card stock paper
Push pins
Foam board
Scissors
String
Tape
Fasteners
Glue
Paper clips
protractors
Activity developed by
Pre College Programs,
USC Viterbi School of Engineering
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Carefully cut out humerus, radius/ulna, and carpal
Bend along lines to form arm segments
Using push pin, poke holes where indicated
Line up holes of humerus with holes of radius/ulna
and insert fastener through both sides
Line up holes of radius/ulna with holes of carpal
and insert fastener through both sides
Cut one strip of foam board 4" x 2", one strip 3" x
2", and two small pieces 1" x 2"
Create standing post
Tape free side of humerus to top of standing post
Tape a string to the proximal end of radius/ulna
Insert paper clip through top of standing post and
bring free end of humerus string through clip
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Questions for Analysis
◦ How many degrees of freedom does your paper
robot arm possess?
◦ Using a protractor, determine the actual degrees of
movement.
◦ Determine the angular displacement
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Part II:
◦ Using what you learned in Part I, design and create
another paper robot are that has three or more
degrees of freedom. You can modify the existing
paper robot arm or you can create a new paper
robot arm
◦ Questions for Analysis:
 How many DOF does your new paper robot arm have?
 Describe the DOF.
 Using a protractor, determine the actual degrees of
each movement.
 Determine the angular displacement for each DOF.
 What was different in design of your new paper robot
arm that allowed for additional DOF?
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Extrinsic Forces
◦ Gravitation force
◦ Fluid force
◦ Contact forces
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Intrinsic Forces
◦ Include muscles, ligaments, and bones
◦ Friction between articular surfaces
◦ Tension of antagonistic muscles, ligament, fasciae,
and capsules
◦ Atmospheric pressure within the join capsule
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Concepts to Consider:
◦ Force Vectors
 Point of application, action line and direction and
magnitude
◦ Force of Gravity
 Gives an object weight, the magnitude of force that
must be applied to an object in order to support it in a
gravitational force
 Weight = mass x 9.8 m/s2 or 32.2 ft/s2
 Center of mass: the point where all of the mass of an
object is concentrated
◦ Equilibrium
 Law of Inertia: every object persists in its state of rest
or uniform motion in a straight line unless it is
compelled to change that state by forces impressed on
it
 ∑F=0
 Law of Acceleration: acceleration is produced when a
force acts on a mass; directly proportional to force and
inversely proportional to mass
 a = F/ m
◦ Reaction Forces
 Law of Reaction: for every action, there is an equal and
opposite reaction
◦ Additional Linear Forces
 Tension: pulling force exerted when an object is being
stretched or elongated
 Compression: force applied to an object tending to
cause a decrease in volume
 Shear: force that moves or attempts to move on
another object
 Torque: the tendency of a force to rotate an object
about an axis
or
 Moment Arm = ⊥d
In A, what is the moment arm?
In B, what is the moment arm?
τ = (F) (moment arm)
◦ Classes of Levers
 First-class levers: effort force and resistance force
located on opposite sides of axis of rotation
 Second-class levers: effort force located at the end of
bar and fulcrum located at other end, with the
resistance force at a point between these two forces
 Third-class levers: effort force is applied between the
resistance force on one end the fulcrum on the
opposite end
 Law of the Lever: Effort Arm x Effort Force =
Resistance Arm x Resistance Force
EA = distance effort force lies from axis of rotation
RA = distance resistance force lies from axis of rotation
◦ Mechanical Advantage (MA)
 Factor by which a mechanism multiplies the force or
torque put into it;
 Ratio of effort arm (EA) to the resistance arm (RA)
 A second-class lever will always have a MA > 1
because EA > RA
 A third-class lever will always have a MA < 1 because
EA < RA
 common in the body and the MA is poor; however, the
speed of rotation created is high because the origin of the
resistance force is located farther from the axis rotation
than the origin of the effort force, it must travel a greater
distance in the same time
 A first-class lever can have a MA <, =, or > than 1,
depending on the locations of the effort force and
resistance force versus the axis of rotation
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Purpose: To create a wooden robot arm with
three degrees of freedom that uses hydraulics
for motion
Materials and Tools:
Plywood
Electrical tape
1” bolts with hex nuts
Sandpaper
Syringes
Scissors
Plastic tubing
Hot glue gun
Film canister tops
Drill with drill bits
Scotch or masking
tape
Saw
Activity developed by
Pre College Programs,
USC Viterbi School of Engineering
Safety Procedure:
Use extreme caution with using
sharp tools, drills, and hot glue gun
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Cut two 6”x3” plywood long rectangles, a 4”x2½ “
plywood medium rectangle, and a 2½”x 2½”
plywood square
Round off corners of each piece w/sandpaper
Humerus: in the middle of one of the long
rectangles, drill three holes
Radius/ulna: in the middle of the other long
rectangle, drill two holes
Carpal: in the middle of the medium rectangle, drill
one hole and one large hole in the center
Line up single hole of humerus with hole of
radius/ulna and insert bolt and nut
Line up remaining hole of radius/ulna with small
hole of carpal and insert bolt and nut
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Cut a strip of plywood 10”x3” and two small pieces
of plywood 1”x3”
On the large strip, drill two holes
Create the standing post by gluing the two small
pieces on both bottom sides of the large plywood
Line up holes of standing post with holes of
humerus and insert bolts and nuts
Using the center of mass, determine the
dimensions of the platform in order to balance the
standing post and the arm structures with nuts and
bolts
Cut plywood to determined dimensions above
Glue standing post vertically to platform
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Three DOF
◦ Determine the best manner in attaching the
syringes, plastic tubing, and film canister tops in
order to create 3 DOF, taking into consideration the
center of mass, torque and classes of levers. You
may use additional materials if needed.
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Questions for Analysis
◦ Calculate the work done by lifting a 147.87 ml (5
oz) dixie cup filled with 100 ml of water to a height
of 10 cm. Hint:
◦ Calculate the torque using the above parameters.
Hint: use
◦ What class of lever is the wooden hydraulic robot
arm? What are the advantages/disadvantages?
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Artificial limb is a type of prosthesis, an
artificial substitute, that replaces a missing
extremity such as an arm
Needed for a various reasons, including
disease, accidents, and congenital defects
History
◦ Roman Capua Leg, found in a tomb in Capua, Italy
dating to 300 BC, was made of cooper and wood
◦ Armorers in the 15th and 16th centuries made
artificial limbs out of iron for soldiers who lost
limbs
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Types
◦ Transradial prosthesis: artificial limb that replaces
an arm missing below the elbow
◦ Transhumeral prosthesis: one that replaces an arm
above the elbow
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Current Technology
◦ New plastics and other materials, such as carbon
fiber, have allowed artificial limbs to be stronger
and lighter
◦ Additional materials allow for a more realistic look
◦ Myoelectric limbs allow more direct control
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Emerging Technology
◦ Robotic limbs
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Purpose: to learn design concepts, teamwork,
problem solving techniques and about simple
machines
Goal: must be 18 inches in length and be able to
pick up an empty Styrofoam cup
Resources/Materials for each group
Developed by IEEE as part
of TryEngineering
5 strips of cardboard
15 paper clips
8 binder clips
4 pencils
10 Brads
15 rubber bands
6 clothespins
Clear and masking tape
15 craft sticks
4 feet twine
4 feet fishing line
Scraps of cardboard
2 hangers
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Model MUST perform 3 tasks: grab, lift, and pour
50ml graduated cylinder with 50ml of sand
Model MUST be operated by push of button(s), pull
of string(s), push or pull of syringe(s), etc. May
NOT perform actual function of grabbing, lifting, or
pouring
Entire base of model MUST fit within a 1.5 foot
square. Any part of model that may be in contact
with the table MUST be within the 1.5 foot square.
Use materials found around the house or school,
taking into consideration cost and weight efficiency
(max points awarded for low cost and low weight)
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Dimensions: 3 ft x 3 ft x 2 ft deep
Freestanding
Synopsis of project, 200 to 250 words
◦ Include purpose of project, explanation of model, and
scientific and engineering ideas involved
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Scaled plan rendering
◦ Three separate 8 ½ x 11 scaled drawings (front, side, and
top views) with dimensions
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Materials Table
◦ Table of all materials used in the model including retail
price, price per unit, quantity used, total cost, and how
each material was acquired (see rules for sample)