COC Anatomy & Biomechanics 2 — Questions and Answers
Question 1: What is the primary function of the plantar fascia during the push-off phase of gait?
- Windlass mechanism to raise the medial longitudinal arch (Correct answer)
- Shock absorption at heel strike
- Control of subtalar eversion
- Stabilization of the Lisfranc joint
Correct answer: Windlass mechanism to raise the medial longitudinal arch
The windlass mechanism tightens the plantar fascia as the toes dorsiflex, raising the arch and storing energy for propulsion.
Question 2: In a transtibial amputation, which residual limb muscle imbalance is most common without surgical correction?
- Plantarflexion contracture from gastrocnemius dominance (Correct answer)
- Dorsiflexion contracture from tibialis anterior dominance
- Eversion contracture from peroneal dominance
- Inversion contracture from posterior tibialis dominance
Correct answer: Plantarflexion contracture from gastrocnemius dominance
Loss of the tibialis anterior's antagonist leads to an unopposed gastrocnemius pull, promoting plantarflexion contracture.
Question 3: Which structure provides the primary static restraint against anterior tibial translation in the knee?
- Anterior cruciate ligament (Correct answer)
- Posterior cruciate ligament
- Medial collateral ligament
- Popliteofibular ligament
Correct answer: Anterior cruciate ligament
The ACL is the primary restraint preventing anterior translation of the tibia on the femur.
Question 4: Ground reaction force (GRF) passes posterior to the knee joint during which phase of normal gait, producing a flexion moment?
- Loading response (Correct answer)
- Mid-stance
- Terminal stance
- Pre-swing
Correct answer: Loading response
During loading response the GRF passes posterior to the knee, creating an external flexion moment resisted by the quadriceps.
Question 5: The subtalar joint axis is oriented approximately how relative to the transverse and sagittal planes?
- 42° from transverse, 16° from sagittal (Correct answer)
- 90° from transverse, 0° from sagittal
- 20° from transverse, 45° from sagittal
- 60° from transverse, 30° from sagittal
Correct answer: 42° from transverse, 16° from sagittal
The subtalar axis averages 42° of inclination from the transverse plane and 16° of deviation medially from the sagittal plane.
Question 6: Which bony landmark serves as the primary weight-bearing contact point of the calcaneus during standing?
- Calcaneal tuberosity (medial and lateral processes) (Correct answer)
- Sustentaculum tali
- Anterior calcaneal facet
- Calcaneal cuboid articular surface
Correct answer: Calcaneal tuberosity (medial and lateral processes)
The medial and lateral processes of the calcaneal tuberosity form the weight-bearing base of the heel during static standing.
COC Anatomy & Biomechanics 2
What is the primary function of the plantar fascia during the push-off phase of gait?