SCS Anatomy & Biomechanics 2 — Questions and Answers
Question 1: Which muscle is the primary dynamic supporter of the medial longitudinal arch of the foot?
- Peroneus longus
- Tibialis anterior
- Tibialis posterior (Correct answer)
- Flexor hallucis longus
Correct answer: Tibialis posterior
The tibialis posterior is the primary dynamic stabilizer of the medial longitudinal arch, coursing beneath and supporting it during weight-bearing.
Question 2: During the overhead throwing motion, which phase produces the greatest valgus stress on the medial elbow?
- Wind-up
- Early cocking
- Late cocking (Correct answer)
- Acceleration
Correct answer: Late cocking
Late cocking generates the greatest valgus stress on the medial elbow as the shoulder reaches maximum external rotation and large deceleration forces build.
Question 3: Femoral anteversion is measured as the angle between which two reference axes?
- Femoral neck axis and the transcondylar axis of the femoral condyles (Correct answer)
- Femoral neck axis and the sagittal plane
- Femoral shaft axis and the horizontal plane
- Greater trochanter to lesser trochanter axis and the transverse axis
Correct answer: Femoral neck axis and the transcondylar axis of the femoral condyles
Femoral anteversion is the angle between the femoral neck axis and the transcondylar axis, reflecting the forward twist of the proximal femur.
Question 4: Which type of muscle contraction generates the greatest force per unit of cross-sectional area?
- Concentric
- Isometric
- Eccentric (Correct answer)
- Isokinetic
Correct answer: Eccentric
Eccentric contractions generate more force per cross-sectional area than concentric or isometric contractions due to titin's passive contribution during muscle lengthening.
Question 5: The pivot shift test evaluates which combination of tibial movements in an ACL-deficient knee?
- Anterior translation and external rotation
- Anterior translation and internal rotation (Correct answer)
- Posterior translation and external rotation
- Valgus stress and external rotation
Correct answer: Anterior translation and internal rotation
The pivot shift tests for anterior tibial translation combined with internal rotation, the coupled motion that the ACL primarily restrains.
Question 6: The thoracolumbar fascia transmits forces diagonally by connecting which two muscles?
- Thoracic erector spinae to iliopsoas
- Latissimus dorsi to contralateral gluteus maximus (Correct answer)
- Serratus anterior to contralateral rhomboids
- Multifidus to contralateral piriformis
Correct answer: Latissimus dorsi to contralateral gluteus maximus
The thoracolumbar fascia creates a cross-body force couple connecting the latissimus dorsi to the contralateral gluteus maximus, stabilizing the lumbar spine.
Question 7: Scapulohumeral rhythm describes which ratio of glenohumeral to scapulothoracic motion during arm elevation?
- 1:1
- 2:1 (Correct answer)
- 3:1
- 4:1
Correct answer: 2:1
Scapulohumeral rhythm is approximately 2:1, meaning for every 2° of glenohumeral motion, 1° of scapulothoracic upward rotation occurs.
SCS Anatomy & Biomechanics 2
Which muscle is the primary dynamic supporter of the medial longitudinal arch of the foot?