CES Human Anatomy & Biomechanics 2 — Questions and Answers
Question 1: In the NIOSH Lifting Equation, what does the load constant (LC) represent?
- Maximum weight ever allowed
- Weight under ideal lifting conditions (23 kg) (Correct answer)
- Average industrial load weight
- Worker's body weight limit
Correct answer: Weight under ideal lifting conditions (23 kg)
The NIOSH load constant of 23 kg (51 lb) represents the maximum recommended load weight under ideal lifting conditions.
Question 2: Which joint in the upper extremity is most vulnerable to cumulative trauma from repetitive overhead work?
- Elbow
- Wrist
- Shoulder (glenohumeral) (Correct answer)
- Acromioclavicular
Correct answer: Shoulder (glenohumeral)
The glenohumeral joint has a wide range of motion but minimal bony stability, making the rotator cuff tendons highly susceptible to impingement during overhead tasks.
Question 3: What is 'ulnar deviation' of the wrist?
- Bending wrist upward
- Bending wrist toward the pinky side (Correct answer)
- Rotating the forearm palm-down
- Bending wrist toward the thumb side
Correct answer: Bending wrist toward the pinky side
Ulnar deviation is lateral flexion of the wrist toward the ulna (pinky side) and is a common risk factor for carpal tunnel syndrome.
Question 4: Which nerve is compressed in cubital tunnel syndrome?
- Median nerve
- Radial nerve
- Ulnar nerve (Correct answer)
- Musculocutaneous nerve
Correct answer: Ulnar nerve
Cubital tunnel syndrome involves compression of the ulnar nerve at the elbow, causing numbness in the ring and pinky fingers.
Question 5: What does 'moment arm' refer to in biomechanics?
- The speed of a rotating limb
- The perpendicular distance from a joint to the line of force (Correct answer)
- The strength of a muscle contraction
- The angle of a joint during movement
Correct answer: The perpendicular distance from a joint to the line of force
The moment arm is the perpendicular distance from the joint axis to the line of action of the force, determining the torque produced.
Question 6: Prolonged static loading of muscles primarily increases the risk of which condition?
- Acute fracture
- Muscle fatigue and ischemia (Correct answer)
- Joint dislocation
- Bone resorption
Correct answer: Muscle fatigue and ischemia
Static muscle contractions restrict blood flow, leading to oxygen deprivation, metabolic waste accumulation, and accelerated fatigue.
CES Human Anatomy & Biomechanics 2
In the NIOSH Lifting Equation, what does the load constant (LC) represent?