OT Kinesiology 4 — Questions and Answers
Question 1: A client with C6 spinal cord injury retains wrist extension but lacks active grasp. Which tenodesis principle allows functional pick-up?
- Wrist flexion passively opens the hand; wrist extension passively closes the fingers (Correct answer)
- Wrist extension passively opens the hand; wrist flexion passively closes the fingers
- Wrist extension drives active finger flexion via active tendons
- Gravity-assisted wrist flexion produces active MCP extension
Correct answer: Wrist flexion passively opens the hand; wrist extension passively closes the fingers
In tenodesis grasp, active wrist extension causes passive finger flexion due to finger flexor tightness, while wrist flexion allows the fingers to open passively.
Question 2: Which of the following best describes the 'force couple' that produces scapular upward rotation during shoulder elevation?
- Upper trapezius and lower trapezius acting in opposite directions on the scapula
- Serratus anterior acting alone on the inferior angle
- Upper trapezius pulling superiorly and serratus anterior pulling the inferior angle anteriorly (Correct answer)
- Rhomboids and middle trapezius working together
Correct answer: Upper trapezius pulling superiorly and serratus anterior pulling the inferior angle anteriorly
Scapular upward rotation is produced by a force couple: upper trapezius elevates the AC joint while serratus anterior pulls the inferior angle forward and upward.
Question 3: During normal standing, the line of gravity relative to the knee joint falls:
- Posterior to the knee, requiring active quadriceps contraction
- Anterior to the knee, keeping it extended passively (Correct answer)
- Directly through the knee axis with no moment arm
- Medial to the knee, stressing the lateral collateral ligament
Correct answer: Anterior to the knee, keeping it extended passively
The body's line of gravity passes anterior to the knee joint axis during relaxed standing, creating an extension moment that keeps the knee locked without significant muscle effort.
Question 4: An OT client presents with 'claw hand' deformity affecting the ring and little fingers. Which nerve injury is most likely?
- Median nerve at the wrist
- Radial nerve at the elbow
- Ulnar nerve at the wrist (Correct answer)
- Median nerve at the elbow
Correct answer: Ulnar nerve at the wrist
Ulnar nerve injury at the wrist causes clawing of the ring and little fingers due to loss of intrinsic muscle function, with hyperextension at MCP and flexion at IP joints.
Question 5: The center of gravity (COG) in a typical adult in anatomical position is located approximately at which vertebral level?
- L1-L2
- S2 (Correct answer)
- L4-L5
- T12
Correct answer: S2
The COG in an average adult is located anterior to the S2 vertebral level, roughly 55–57% of total body height from the ground.
Question 6: Which muscle is the primary responsible for the 'power' phase of the jaw during mastication and is assessed when evaluating cranial nerve V function in OT?
- Temporalis
- Masseter (Correct answer)
- Medial pterygoid
- Lateral pterygoid
Correct answer: Masseter
The masseter is the most powerful jaw-closing muscle and is the primary muscle producing biting force, innervated by the mandibular branch of CN V.
Question 7: In OT practice, the 'length-tension relationship' of muscle means that a muscle produces maximum active force when:
- It is at its shortest (fully contracted) length
- It is at a length slightly greater than its resting length (Correct answer)
- It is maximally stretched beyond resting length
- Force is independent of muscle length
Correct answer: It is at a length slightly greater than its resting length
Maximum active force production occurs near or slightly above the resting length where actin-myosin cross-bridge overlap is optimal.
OT Kinesiology 4
A client with C6 spinal cord injury retains wrist extension but lacks active grasp.
Which tenodesis principle allows functional pick-up?