OT Kinesiology 3 — Questions and Answers
Question 1: Which rotator cuff muscle is most commonly torn and is responsible for initiating shoulder abduction from 0–15 degrees?
- Infraspinatus
- Subscapularis
- Supraspinatus (Correct answer)
- Teres minor
Correct answer: Supraspinatus
The supraspinatus initiates shoulder abduction and is the most frequently torn rotator cuff muscle due to its vulnerable position under the acromion.
Question 2: A client with a radial nerve injury at the spiral groove presents with which primary deficit relevant to hand function?
- Loss of wrist flexion and finger flexion
- Loss of wrist extension and finger extension (wrist drop) (Correct answer)
- Loss of thumb opposition and palmar sensation
- Loss of finger abduction and adduction
Correct answer: Loss of wrist extension and finger extension (wrist drop)
Radial nerve injury at the spiral groove results in wrist drop due to paralysis of wrist and finger extensors, impairing functional grasp patterns.
Question 3: The scapulohumeral rhythm describes the ratio of glenohumeral to scapulothoracic movement during shoulder abduction. What is this ratio?
- 3:1 glenohumeral to scapulothoracic
- 1:2 glenohumeral to scapulothoracic
- 2:1 glenohumeral to scapulothoracic (Correct answer)
- 1:1 glenohumeral to scapulothoracic
Correct answer: 2:1 glenohumeral to scapulothoracic
The scapulohumeral rhythm is approximately 2:1, meaning for every 3° of shoulder abduction, 2° occur at the glenohumeral joint and 1° at the scapulothoracic articulation.
Question 4: An OT is analyzing a client's pinch strength. Which joint is primarily stabilized by the first dorsal interosseous muscle during lateral (key) pinch?
- Carpometacarpal joint of the thumb
- Metacarpophalangeal joint of the index finger (Correct answer)
- Proximal interphalangeal joint of the index finger
- Interphalangeal joint of the thumb
Correct answer: Metacarpophalangeal joint of the index finger
The first dorsal interosseous abducts the index finger and stabilizes its MCP joint, providing the radial force necessary for lateral pinch against the thumb.
Question 5: When analyzing torque in a therapeutic exercise, which variable, if doubled, would have the greatest effect on increasing torque?
- The mass of the segment
- The angle of muscle pull
- The moment arm length (Correct answer)
- The velocity of movement
Correct answer: The moment arm length
Torque = Force × moment arm; doubling the moment arm doubles the torque, making it the most direct way to increase rotational force in joint mechanics.
Question 6: Which gait phase places the greatest demand on the quadriceps to control knee flexion and prevent buckling?
- Initial contact (heel strike)
- Loading response (Correct answer)
- Terminal swing
- Pre-swing
Correct answer: Loading response
During loading response, the knee flexes to absorb shock, requiring eccentric quadriceps activation to prevent excessive knee collapse under body weight.
Question 7: The lumbrical muscles of the hand perform which unique combination of joint actions?
- MCP flexion and IP extension (Correct answer)
- MCP extension and IP flexion
- MCP and IP flexion simultaneously
- MCP and IP extension simultaneously
Correct answer: MCP flexion and IP extension
Lumbricals flex the MCP joints while simultaneously extending the IP joints via their attachment to the extensor expansion, enabling intrinsic-plus hand posture.
OT Kinesiology 3
Which rotator cuff muscle is most commonly torn and is responsible for initiating shoulder abduction from 0–15 degrees?