NCBTMB Kinesiology and Biomechanics 4 — Questions and Answers
Question 1: The term 'agonist' in muscle function refers to:
- A muscle that opposes the prime mover
- The primary muscle responsible for producing a movement (Correct answer)
- A muscle that stabilizes a joint
- A muscle active during the return phase of movement
Correct answer: The primary muscle responsible for producing a movement
The agonist (prime mover) is the muscle primarily responsible for producing the desired movement at a joint.
Question 2: Scapular winging is most commonly caused by weakness of which muscle?
- Rhomboid major
- Middle trapezius
- Serratus anterior (Correct answer)
- Subscapularis
Correct answer: Serratus anterior
Serratus anterior weakness allows the medial border of the scapula to lift away from the thoracic wall, producing the characteristic winging appearance.
Question 3: Which joint in the ankle is primarily responsible for dorsiflexion and plantarflexion?
- Subtalar joint
- Midtarsal joint
- Talocrural (tibiotalar) joint (Correct answer)
- Tarsometatarsal joint
Correct answer: Talocrural (tibiotalar) joint
The talocrural (tibiotalar) joint is the true ankle joint and is the primary site for dorsiflexion and plantarflexion movements.
Question 4: Reciprocal inhibition refers to the phenomenon where:
- Agonist and antagonist contract simultaneously
- Contraction of the agonist causes reflex relaxation of the antagonist (Correct answer)
- Stretch of a muscle causes reflex contraction
- A muscle fatigues and is inhibited from further contraction
Correct answer: Contraction of the agonist causes reflex relaxation of the antagonist
Reciprocal inhibition is a neurological reflex where activation of the agonist causes simultaneous inhibition (relaxation) of the antagonist muscle.
Question 5: The Q-angle is a clinical measurement relevant to which joint?
- Hip joint
- Ankle joint
- Patellofemoral joint (Correct answer)
- Sacroiliac joint
Correct answer: Patellofemoral joint
The Q-angle (quadriceps angle) measures the alignment between the quadriceps pull and the patellar tendon, making it clinically relevant to patellofemoral joint mechanics.
Question 6: Which type of lever system is found at the ankle during plantarflexion (rising on toes)?
- First-class lever
- Second-class lever (Correct answer)
- Third-class lever
- Fourth-class lever
Correct answer: Second-class lever
Plantarflexion via the calf muscles represents a second-class lever where the load (body weight at the ball of the foot) is between the fulcrum (metatarsal heads) and the effort (Achilles tendon).
Question 7: Carpal tunnel syndrome most commonly compresses which nerve?
- Ulnar nerve
- Radial nerve
- Median nerve (Correct answer)
- Musculocutaneous nerve
Correct answer: Median nerve
The median nerve passes through the carpal tunnel and is the nerve most commonly compressed in carpal tunnel syndrome, causing tingling and weakness in the hand.
