ERGONOMIC SUMMARY.pptx, way of movement in humans

It's about ergonomics

1. Kinesiology Definition : The study of movement as related to the human body. Origins from Greek word Kinesis “to move” and ology “to study”

2. Terminologies Kinematics : motion of the body without regard to forces Translation : when all parts of a “body” move in the same direction Rectilinear motion: straight line Curvilinear motion :curved line Rotation ( movement of body about an axis) “ Pivot-point ” - the axis of rotation that the movement occurs about Active movements: Own body part movement Passive movements: movement by external force

3. Anterior: toward the front of the body Posterior: toward the back of the body Midline: an imaginary line that courses vertically through the center of the body Medial: toward the midline of the body Lateral: away from the midline of the body Superior: above, or toward the head Inferior : below, or toward the feet Proximal: closer to, or toward the torso

4. Distal : away from the torso Cephalad : toward the head Caudal: toward the feet, or “tail” Deep: toward the inside (core) of the body Origin: the proximal attachment of a muscle or ligament Insertion: the distal attachment of a muscle or ligament Prone: describes the position of an individual lying face down Supine: describes the position of an individual lying face up  

5. Osteokinematics : describes the motion of bones relative to the three cardinal planes Planes of motion Sagittal plane: left-right division Frontal plane: front-back division Horizontal (transverse) plane: top-bottom division Anatomic position Neutral positions Degrees of freedom Number of planes of motion joint allows A joint can have 1, 2, or 3 degrees of angular freedom

6. Axis of rotation : pivot-point” Flexion: Motion of one bone approaching the flexor surface of another Extension : An approximation of the extensor surfaces of two bones Abduction : Frontal plane movement away from the midline Adduction: Frontal plane movement toward the midline Rotation: Bony segment spinning about its longitudinal axis of rotation Internal rotation: Anterior bone surface rotates toward the midline External rotation: Anterior bone surface rotates away from the midline

7. Circumduction : A circular motion through two planes Protraction: Translation of bone away from midline in a plane parallel to the ground Retraction: Movement of a bony segment toward the midline in a plane parallel to the ground Horizontal adduction and abduction Shoulder motions in the transverse plane Horizontal adduction: hands come together Horizontal abduction: extremities move away from midline

8. Pronation: Forearm movement that turns the palm posteriorly Supination : Forearm movement that turns the palm anteriorly Radial deviation: Lateral hand movement toward the radius Ulnar deviation: Medial hand movement toward the ulna Dorsiflexion: Sagittal plane ankle motion bringing the foot upward Plantar flexion : Sagittal plane ankle motion pushing the foot downward

9. Inversion and eversion Inversion results in a medial-facing foot sole Eversion results in a lateral-facing foot sole Two perspectives of movement at a joint Open-chain motion Movement of distal segment of bone about a relatively fixed proximal segment Example: bicep curl with weights Closed-chain motion Movement of proximal segment of bone about a relatively fixed distal segment Example: pushups

10. Convex-concave joint relationship Improves fit and stability Properly guides motion Fundamental movements of arthrokinematics vary Depend on whether concave articular surface is moving on a fixed convex surface or vice versa Roll Multiple points along one rotating articular surface contact multiple points on another articular surface e.g., a tire rotating across a stretch of pavemen t

11. Slide Single point on one articular surface contacts multiple points on another articular surface e.g., a stationary tire skidding across a stretch of icy pavement Spin Single point on one articular surface rotates on a single point on another articular surface e.g., rotating toy top spinning on one spot on the floor

12. Convex-on-Concave When a convex joint surface moves on a concave joint surface, the roll and slide occur in OPPOSITE directions! Concave-on-Convex When a concave joint surface moves about a stationary convex joint surface, the roll and slide occur in the SAME direction!

13. Roll-and-slide mechanics Roll–and–opposite-direction slide maintains articular stability To maintain firm surface contact, motion must be accompanied by slide in same direction Spin mechanics Spin always occurs about a central longitudinal axis of rotation

14. Kinetics Branch of mechanics that describes the effect of forces on the body Force “ Push or pull” that can produce, modify, or halt a movement Internal force is generated within the body External force is generated outside the body

15. Torque Torque is the rotational equivalent of force Amount generated across a joint depends on: Amount of force exerted Distance between force and axis of rotation (moment arm) Internal torques are generated internally (e.g., muscle) External torques are generated externally (e.g., gravity) Force x Movement Arm = Torque Muscular Force x Internal Movement Arm = Internal Torque External Force x External Movement Arm = External Torque

16. Biomechanical Levers First-class lever Similar to a see-saw; fulcrum located between internal and external force Second-class levers Axis of rotation located at one end of the bony lever; internal moment arm always longer than the external moment arm Allows motion with little amount of muscle force Third-class levers Axis of rotation located at one end of the bony lever; internal moment arm always smaller than the external moment arm Most biomechanical lever systems in the body are third-class Designed for speed and distance

17. Line of Pull Line of pull describes the direction of muscular force Medial-lateral axis of rotation Bony motion anterior of the sagittal plane Anterior-posterior axis of rotation Lateral motion pulls bone laterally Medial motion pulls bone medially Vertical axis of rotation Anterior or medial pull produces inward rotation Posterior or lateral pull produces rotation away from the midline

18. Vectors Vectors represent the magnitude and direction of a force Magnitude of force indicated by relative length of vector line Direction is indicated by orientation of arrowhead Resultant is resulting combination of vector forces Two Equal Force Vectors Two Unequal Force Vectors  

19. Motion and Forces in 2 and 3 Dimensions A torque is an action that causes objects to rotate. Torque is not the same thing as force. For rotational motion, the torque is what is most directly related to the motion, not the force. Motion in which an entire object moves is called translation. Motion in which an object spins is called rotation. The point or line about which an object turns is its center of rotation. An object can rotate and translate.

20. Torque is created when the line of action of a force does not pass through the center of rotation. The line of action is an imaginary line that follows the direction of a force and passes though its point of application.

21. To get the maximum torque, the force should be applied in a direction that creates the greatest lever arm. The lever arm is the perpendicular distance between the line of action of the force and the center of rotation

22. Statics - study of systems that are in a constant state of motion, whether at rest with no motion or moving at a constant velocity without acceleration   Statics involves all forces acting on the body being in balance resulting in the body being in equilibrium   Dynamics - study of systems in motion with acceleration  

23. HUMAN MOBILITY

24. Flexibility Flexibility is the absolute range of motion in a joint or system of joints, and the length of muscle that crosses the joint involved.

25. Mobility Mobility within a joint is the degree to which the area where two bones meet (known as an articulation) is allowed to move before restricted by the surrounding tissue such as tendons, muscle, and ligaments. A good level of mobility allows a person to perform movements without restriction, while a person with good flexibility may not have the strength, coordination, or balance to execute the same movement. Mobility is the combination of: Muscle flexibility The range of motion at the joint, and The freedom of movement that each particular body segment has

26. Stability Stability is defined as the ability to maintain control of joint movement or position by coordinating actions of surrounding tissues and the neuromuscular system. Stability is the ability to maintain posture and/or control motion, both in activities that are performed without moving, such as bending over to pick something up, or in dynamic movements, such as running

27. Joint stability depends largely on the shape, size, and arrangement of the articular surfaces (the surfaces on joints and cartilage where the bone makes contact with another bone), the surrounding ligaments, and the tone of the surrounding muscle. Injuries including ligament tears and sprains can often lead to stability issues in the joint. Therefore, stability can be divided into two categories: Static stability Dynamic stability

28. BODY EQUILIBRIUM Centre of gravity Is the part at which the body weight is concentrated Approximately 2 inches below the umbilicus Factors that determine the COG Ambulation – whether the body is in motion or not Anatomical structure of the individual Posture Carrying of objects

29. Line of gravity Points of intersection between the saggital plane and horizontal plane Passes through the COG in upright position The line of gravity is dependent on the center of gravity Base of support The area within an outline of all ground contact points The bigger the base of support the greater the stability

30. Five factors determine stability and mobility     From a mechanical perspective, five factors determine our levels of stability and mobility. Size of the base of support in the direction of force or impending force   Increasing the size of the base of support increases stability. The increase must be made in the direction of force or impending force. Increases in base of support can be made by placing the feet in a certain position, or by adding ground contact points. Additional contact points can be added by using other body parts, as when a baby creeps along the ground on hands and knees or when an athlete assumes a three-point or four-point stance. Older or injured persons also can enhance their stability by using a cane or crutch to add contact points to the system, thereby increasing their bases of support  

31. 2. Height of the center of gravity above the base of support When you squat down to improve your stability, you lower your center of gravity, or decrease the height of the center of gravity above the base of support. Conversely, standing up straight raises the center of gravity above the base of support and decreases stability.

32. Height of the center of gravity above the base of support       3. Location of the center of gravity projection within the base of support In normal standing, when the center of gravity projection lies at or near the center of the base of support, you are more stable than when the projection lies near the edge of the base of support. When another body is about to collide with yours, you tend to lean toward the colliding body. This lean moves the projection near the edge of the base of support so that at impact, the center of gravity has a greater distance to travel before leaving the base of support on the opposite side and causing you to fall.

33. 4. Body mass or body weight A body’s mass (or weight) contributes to stability. Simply stated, heavier bodies are harder to move and hence are more stable. Lighter bodies are moved more easily and are less stable.

34. 5. Friction The amount of frictional resistance at the interface between the ground and any contact points (e.g., foot or shoe) contributes to stability and mobility.

35. In summary, High stability (low mobility) is characterized by a large base of support, a low center of gravity, a centralized center of gravity projection within the base of support, a large body mass, and high friction at the ground interface. Low stability (high mobility), in contrast, occurs with a small base of support, a high center of gravity, a center of gravity projection near the edge of the base of support, a small body mass, and low friction.

36. TYPES OF TRANSFERS Sliding transfer Three person carry Two person lift Wheelchair to floor Dependent standing pivot Sliding board Push up Squat pivot transfer Floor to wheelchair

37. ERGONOMICS Ergonomics is the science of designing a person's environment so that it facilitates the highest level of function. A person's work environment should fit his or her capabilities as a worker. Good ergonomics prevent injury and promote health, safety, and comfort for employees.

38. The association between occupations and musculoskeletal injuries was documented centuries ago. Bernardino Ramazinni (1633-1714) wrote about work-related complaints (that he saw in his medical practice) in the 1713 supplement to his 1700 publication, "De Morbis Artificum (Diseases of Workers)."

39. Wojciech Jastrzebowski created the word ergonomics in 1857 in a philosophical narrative, "based upon the truths drawn from the Science of Nature" ( Jastrzebowski , 1857). In the early 1900's, the production of industry was still largely dependent on human power/motion and ergonomic concepts were developing to improve worker productivity. Scientific Management, a method that improved worker efficiency by improving the job process, became popular

40. Frederick W. Taylor was a pioneer of this approach and evaluated jobs to determine the "One Best Way" they could be performed. At Bethlehem Steel, Taylor dramatically increased worker production and wages in a shoveling task by matching the shovel with the type of material that was being moved (ashes, coal or ore).

41. Frank and Lillian Gilbreth made jobs more efficient and less fatiguing through time motion analysis and standardizing tools, materials and the job process. By applying this approach, the number of motions in bricklaying was reduced from 18 to 4.5 allowing bricklayers to increase their pace of laying bricks from 120 to 350 bricks per hour.

42. World War II prompted greater interest in human-machine interaction as the efficiency of sophisticated military equipment (i.e., airplanes) could be compromised by bad or confusing design. Design concepts of fitting the machine to the size of the soldier and logical/understandable control buttons evolved.

43. After World War II, the focus of concern expanded to include worker safety as well as productivity. Research began in a variety of areas such as: Muscle force required to perform manual tasks Compressive low back disk force when lifting Cardiovascular response when performing heavy labor Perceived maximum load that can be carried, pushed or pulled

44. Areas of knowledge that involved human behavior and attributes (i.e., decision making process, organization design, human perception relative to design) became known as cognitive ergonomics or human factors. Areas of knowledge that involved physical aspects of the workplace and human abilities such as force required to lift, vibration and reaches became known as industrial ergonomics or ergonomics.

45. IMPORTANCE OF ERGONOMICS The use of ergonomics principles can increase worker productivity and quality. Employers can implement a program that includes guidelines for employees to follow, Which contributes to an efficient work environment, Prevents injuries and the development of chronic medical conditions, Helps employees return to work after an injury has occurred. Occupational therapy practitioners are trained in the structure and function of the human body and the effects of illness and injury. They can determine how the components of the workplace Can facilitate a healthy and efficient environment or one that could cause injury or illness. Can help employers identify hazards that may contribute to on-the-job injury, and determine how it can be eliminated.

46. What can an occupational therapist do? Identify and eliminate accident and injury risk factors in the workplace, such as actions associated with repetition, force, fixed or awkward postures, poorly designed tool handles, heavy loads, distance, vibration, noise, extreme temperatures, poor lighting, and psychosocial and other occupational stresses. Analyze job functions and job descriptions based on job tasks. Design pre-hire screenings to determine a candidate's suitability to a particular job. Modify tools and equipment so that they do not enable injury or illness. Provide education and training on injury prevention, workplace health and safety regulations, and managing job-related stress. Determine reasonable accommodations and worksite accessibility that is in compliance with the Americans With Disabilities Act. Recommend changes employers can take to minimize injury and accident risk factors.

47. What can a person do to employ good ergonomics in the workplace? Take a proactive approach to preventing injury in the workplace. Follow guidelines set forth by employers that may prevent injury and illness. Report hazards or poor work conditions or employee behavior that may contribute to

48. What can a person do to employ good ergonomics in the workplace? Take a proactive approach to preventing injury in the workplace. Follow guidelines set forth by employers that may prevent injury and illness. Report hazards or poor work conditions or employee behavior that may contribute to illness or injury in the workplace.

49. 10 PRINCIPLES OF ERGONOMICS Work in neutral positions Reduce excessive force Keep everything within easy reach Work at proper heights Reduce excessive motions Minimize fatigue and static load Minimize pressure points Provide clearance within the working environment Move, exercise and stretch Maintain a comfortable environment

50. Condition Probable Cause How to Correct 1. Neck tension, tightness, upper back and shoulder discomfort.   1a. Head is too far forward during reading, writing, or viewing the VDT screen 1a. Elevate work surface, reading materials, and VDT screen so as to keep the head and trunk relationship more vertical 1b. Hands and arms not supported while typing, inputting data, writing or using hands in manipulating or holding work. 1b. For typing tasks, adjust the armrests to the correct height and angle to support the weight of the arms and use palm rest or wrist rest. 1c. Head is too far back during reading, writing or viewing VDT screen. 1c. tilt the seat and backrest forward so as to keep the head and trunk relationships more vertical. 1e. Head and neck are tilted in a lateral direction holding the telephone between the shoulder and ear. 1e. Use headset. Managing Workplace Discomfort

51. 4. Buttocks discomfort. 4a. Sitting too far forward in the seat pan and not using the backrest. 4a. Open up the trunk/thigh angle towards the neutral position.

52. MUSCULOSKELETAL DISORDERS Disorders due to poor ergonomics Assign: mention the disorders, risk factors, prevention and remedy