AK Biomechanics & Body Movement Analysis 2 — Questions and Answers
Question 1: Which type of lever is present at the ankle joint during plantar flexion (gastrocnemius lifting the heel)?
- First-class lever
- Second-class lever (Correct answer)
- Third-class lever
- Fourth-class lever
Correct answer: Second-class lever
The ankle in plantar flexion is a second-class lever because the load (body weight at the ball of the foot) lies between the fulcrum (metatarsophalangeal joints) and the effort (calf muscles at the calcaneus).
Question 2: When analyzing gait, which plane primarily describes the forward progression of the body?
- Frontal plane
- Transverse plane
- Sagittal plane (Correct answer)
- Coronal plane
Correct answer: Sagittal plane
The sagittal plane divides the body into left and right halves and contains the flexion/extension movements that drive forward locomotion.
Question 3: A patient demonstrates excessive lateral trunk lean toward the stance limb during walking. Which muscle weakness is most likely responsible?
- Gluteus maximus
- Gluteus medius (Correct answer)
- Tensor fasciae latae
- Adductor longus
Correct answer: Gluteus medius
Weakness of the gluteus medius causes a Trendelenburg gait where the trunk leans toward the weak side to keep the center of mass over the support limb.
Question 4: The term 'valgus' at the knee describes which positional deviation?
- Distal segment angled medially (knock-kneed) (Correct answer)
- Distal segment angled laterally (bow-legged)
- Posterior tibial displacement
- Anterior femoral rotation
Correct answer: Distal segment angled medially (knock-kneed)
Valgus means the distal bone angles toward the midline, producing a knock-kneed appearance where the knees converge medially.
Question 5: Which concept in biomechanics describes the resistance of an object to a change in its rotational motion?
- Linear momentum
- Moment of inertia (Correct answer)
- Ground reaction force
- Center of pressure
Correct answer: Moment of inertia
Moment of inertia quantifies how mass distribution relative to the axis of rotation resists angular acceleration or deceleration.
Question 6: During a squat, which joint action occurs at the hip during the descent phase?
- Extension with external rotation
- Flexion with internal rotation
- Flexion with external rotation (Correct answer)
- Abduction with flexion
Correct answer: Flexion with external rotation
Hip flexion combined with slight external rotation and abduction is the typical pattern during a controlled squat descent to allow acetabular clearance.
Question 7: Which term describes the tendency of collagenous tissue to gradually deform under a constant load over time?
- Elasticity
- Creep (Correct answer)
- Yield point
- Plasticity
Correct answer: Creep
Creep is the time-dependent deformation of viscoelastic tissue (such as ligament or tendon) when subjected to a sustained load.
AK Biomechanics & Body Movement Analysis 2
Which type of lever is present at the ankle joint during plantar flexion (gastrocnemius lifting the heel)?