BLOCK 5: PHYSICAL/BIOLOGICAL HAZARDS AND CONTROLS - Unit 8: Ergonomic/Human Factors (complete) Flashcards
The field of study that focuses on evaluating the interactions amongst workers and their environments.
ERGONOMICS
Ergonomics can be defined simply as the study of work. More specifically, ergonomics is the science of designing the job to fit the worker rather than physically forcing the worker’s body to fit the job.
PHYSICAL RISK FACTORS
The orientation of the task (work) to the body. Body postures determine which joints and muscles are used in an activity and the amount of force or stresses that are generated or tolerated.
AWKWARD POSTURE
PHYSICAL RISK FACTORS
Tasks that place higher loads on the muscles, tendons, ligaments, and joints. Increasing force means increasing body demands such as greater muscle exertion along with other physiological changes necessary to sustain an increased effort.
FORCEFUL EXERTION
Force requirements may increase with:
* Increased weight of a load handled or lifted
* Increased bulkiness of the load handled or lifted
* Use of an awkward posture
* The speeding up of movements
* Increased slipperiness of the objects handled (requiring increased grip force)
* The presence of vibration (e.g., localized vibration from power hand tools leads to use of an increased grip force)
* Use of the index finger and thumb to forcefully grip an object (i.e. a pinch grip compared with gripping the object with your whole hand)
* Use of small or narrow tool handles that lessen grip capacity
PHYSICAL RISK FACTORS
When motions are repeated frequently (e.g., every few seconds) and for prolonged periods such as an 8-hour shift, under which conditions, fatigue and muscle-tendon strain can accumulate.
REPETITIVE MOTIONS
PHYSICAL RISK FACTORS
Also known as a dead load; this is where the worker is holding a large amount of weight with minimal movement.
STATIC LOADS
PHYSICAL RISK FACTORS
The amount of time a person is continually exposed to a risk factor.
DURATION
In general, the longer the period of continuous work (e.g., tasks requiring sustained muscle contraction), the longer the recovery or rest time required.
PHYSICAL RISK FACTORS
Refers to how many times a person repeats a given exertion within a given period of time.
FREQUENCY
PHYSICAL RISK FACTORS
Repeated or continuous contact with hard or sharp objects such as non-rounded desk edges or unpadded, narrow tool handles may create pressure over one area of the body (e.g., the forearm or sides of the fingers) that can inhibit nerve function and blood flow.
CONTACT STRESSES
PHYSICAL RISK FACTORS
When a specific part of the body comes in contact with a vibrating object, such as a power hand tool.
VIBRATION
PHYSICAL RISK FACTORS
Other workplace conditions that can influence the presence and magnitude of the risk factors for MSDs can include:
- Cold temperatures
- Insufficient pauses and rest breaks for recovery
- Machine paced work
- Unfamiliar or unaccustomed work
The measure of how much energy is used to produce a given result.
FORCE
Other aspects of work may not only contribute to physical stress but ____________________ stress as well, such as when a worker is performing a task under distress.
PSYCHOLOGICAL
A group of conditions that involve the nerves, tendons, muscles, and supporting structures.
MUSCULOSKELETAL DISORDERS
Ergonomic related illnesses attributed to poorly designed job tasks or equipment that lack application of proper ergonomic principles in their design.
WORK-RELATED MUSCULOSKELETAL DISORDERS (WMSD)
Parts of the body most affected by MSDs are:
- Arms
- Hands
- Fingers
- Neck
- Back
- Wrists
- Legs
- Shoulders
A disorder of the hand characterized by pain, weakness, and numbness in the fingers and caused by nerve compression in the wrist; occurs when the median nerve is compressed within the carpal tunnel area.
CARPAL TUNNEL SYNDROME
The nerve can be trapped when the tendons become inflamed or swollen when the sheath becomes irritated and inflamed. This may result from direct pressure on the nerve from hard, sharp edges of work surfaces or tools, repetitive motion, and/or awkward wrist postures. It can lead to numbness, tingling, weakness, and/or muscle damage in the hand and fingers.
An entrapment neuropathy of the median nerve, where it passes between the two heads of the pronator teres muscle. This muscle attaches to the lower humerus, as well as the inner ulna bone. It is between these two heads, that the median nerve can become entrapped.
PRONATOR TERES SYNDROME
Symptoms of pronator syndrome can be similar to carpal tunnel syndrome, so it is important to distinguish between them. With carpal tunnel syndrome there will be no weakness or pain with turning the palm down (pronation) and the pronator teres muscle is not tender to the touch. Cases of carpal tunnel syndrome also do not cause neural symptoms such as numbness or tingling in the palm of the hand. Pronator syndrome usually occurs after prolonged or repetitive forceful grasping with the hand and twisting at the wrist. These kinds of movements are common in manual occupations such as carpentry and mechanics.
A painful inflammation of tendons in the thumb side of the wrist.
DE QUEVERVAIN’S TENOSYNOVITIS
Chronic overuse of the wrist is commonly associated with de Quervain’s. When you grip, grasp, clench, pinch, or wring anything in your hand, you use two major tendons in your wrist and lower thumb. These tendons normally glide unhampered through the small tunnel that connects them to the base of the thumb. (Figure 60) Repetition of a particular motion day after day can irritate the sheath around the two tendons, causing thickening that restricts the movement of the tendons.
An inflammation of an epicondyle which is a rounded articular, or joint,
area.
EPICONDYLITIS
Types include:
* Lateral epicondylitis, also known as tennis elbow
* Medial epicondylitis, also known as golfer’s elbow
Refers to inflammation within the shoulder joint, either to the tendons of the rotator cuff or the bursa.
SHOULDER TENDONITIS
The main symptom is pain. The pain may be felt when the arm is raised overhead or outstretched. The pain is located in the front of the shoulder and upper arm. Shoulder tendonitis/bursitis is often the result of repetitive, or overuse.
A sac-like swelling or cyst formed from the tissue that lines a joint or tendon.
GANGLION
Ganglia can form around any joint, but they are most frequently found in the wrist and ankles. While ganglia can follow local trauma to the tendon or joint, they usually form for unknown reasons.
Muscle pain or tension localized around the neck. Bending over a desk for hours, having poor posture, placing the computer monitor too high or too low, or twisting and turning the neck in a jarring manner are all contributing factors. Symptoms include:
- Aching discomfort at the base of neck and upper back.
- Headaches due to tension in neck muscles.
- Intermittent muscle spasms in neck muscles.
- Dull pain may refer to the upper limb, elbow, forearm, and hands.
TENSION NECK SYNDROME
Occurs when the ulnar nerve in the arm becomes compressed or irritated.
ULNAR NERVE ENTRAPMENT
The ulnar nerve is one of the three main nerves in your arm. It travels from your neck down into your hand, and can be constricted in several places along the way. Depending upon where it occurs, this pressure on the nerve can cause numbness or pain in your elbow, hand, wrist, or fingers. Sometimes the ulnar nerve gets compressed at the wrist, beneath the collarbone, or as it comes out of the spinal cord in the neck. The most common place where the nerve gets compressed is behind the elbow. When the nerve compression occurs at the elbow, it is called “cubital tunnel syndrome.”
