Senior MESA Day
Overview of the Human Arm Anatomy Bones, Joints, Muscles 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 Overview of the Prosthetic Arm Building the Model Building the Display
Humerus The longest and largest bone in the upper extremity. Ulna A long bone in the forearm parallel with the radius; at the proximal is the elbow and the distal end is the wrist. Radius The other bone of the forearm, shorter than the ulna.
Carpals The wrist is composed of 8 separate carpal bones. Metacarpals The intermediate part of the hand skeleton that is between the carpals and the phalanges (up to the knuckles); 5 metacarpal cylindrical bones Phalanges The fingers of the hand contain 14 digital bones.
Elbow Joint/Complex Humeroulnar Joint simple hinge-joint Humeroradial Joint arthrodial joint allowing gliding and sliding motions Proximal Radioulnar Joint pivot joint Wrist Joint Radiocarpal joint Carpometacarpal joints Intercarpal joints intercarpal joints carpometac arpal joint midcarpal joint radiocarpal joint
Metacarpophalangeal Joints Interphalangeal Joints interphalangeal joints
Flexion: decreasing joint angle such as bending Extension: increased joint angle such as stretching Abduction: movement that draws limb away from sagittal plane Adduction: movement which brings limb closer to the sagittal plane Supination: palm faces up Pronation: palm faces down Circumduction: combination of flexion, extension, abduction and adduction
Upper Arm Biceps brachii, brachialis, coracobrachialis Forearm Flexor-pronator and extensor-supinator Hand Thenar, hypothenar, interosseous, lumbrical
Arm Muscles and Their Functions Muscle Location Function Biceps brachii Anterior Arm (humerus) 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) Pronation of forearm; flexion of the elbow Pronator quadratus Anterior Forearm (deep layer) 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 Posterior Forearm (deep layer) Supination of forearm and wrist Extensor carpi radialis longus Posterior Forearm (superficial) Extension and abduction of the wrist Extensor carpi radialis brevis Posterior Forearm (superficial) Extension and abduction of the wrist Anterior of forearm 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
Tough bands of fibrous connective tissue that connects muscles to bones. Capable of withstanding tension Function to transmit force Function as springs
Types of Motion Translatory: all parts move toward same direction Rotatory/Angular: around a fixed axis General: combination of translation and rotation 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 (anterior posterior axis) Coronal axis (frontal axis) Vertical axis Horizontally from front to back Horizontally from side to side Perpendicular to ground Coronal plane Sagittal plane Transverse plane y - vertical axis x - coronal axis z sagittal axis
Magnitude of Translatory Motion Displacement: change of position that an object moves from the reference point C 3 m 3.6 m Velocity: rate of change in displacement v = dx / dt B 2 m A Acceleration: rate of change in velocity over time A = dv / dt
Magnitude of Rotatory Motion Angular displacement: rotation of an object about an axis in radians Δθ = Δθ 2 Δθ 1 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
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 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)
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
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?
Extrinsic Forces Gravitation force Fluid force Contact forces 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
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/s 2 or 32.2 ft/s 2 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 τ = (F) (moment arm) Moment Arm = d In A, what is the moment arm? In B, what is the 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
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 15 th and 16 th centuries made artificial limbs out of iron for soldiers who lost limbs
Types Transradial prosthesis: artificial limb that replaces an arm missing below the elbow Transhumeral prosthesis: one that replaces an arm above the elbow 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 Emerging Technology Robotic limbs
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)
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 Scaled plan rendering Three separate 8 ½ x 11 scaled drawings (front, side, and top views) with dimensions 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)