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.
NCBTMB Kinesiology and Biomechanics 4
The term 'agonist' in muscle function refers to: