OCS Biomechanics & Kinesiology Flashcards

The convex-concave rule states that when a convex surface moves on a fixed concave surface, joint glide occurs in which direction relative to bone movement?

Answer: Opposite direction

When a convex surface moves on a concave surface, the joint glide (slide) occurs in the opposite direction of the bone's angular movement.

During the running gait cycle, which phase is absent compared to walking gait?

Answer: Double support phase

Running eliminates the double support phase seen in walking and replaces it with a float phase where neither foot is in contact with the ground.

The center of gravity in a standing adult is located approximately at which spinal level?

Answer: S2

The center of gravity in a standing adult is located approximately anterior to the second sacral vertebra (S2).

Which type of muscle contraction produces the greatest tension per cross-sectional area?

Answer: Eccentric

Eccentric contractions produce greater tension than isometric or concentric contractions because cross-bridge cycling is supplemented by passive elastic forces in titin.

The subtalar joint axis of motion is oriented at approximately 42° in the sagittal plane and 16° in the transverse plane; this orientation means subtalar pronation is a triplanar motion combining:

Answer: Eversion, dorsiflexion, and abduction

Subtalar pronation is a triplanar motion consisting of calcaneal eversion, talar dorsiflexion, and forefoot abduction occurring simultaneously.

The instantaneous axis of rotation (IAR) of the knee joint during flexion-extension moves in what pattern?

Answer: Posteriorly during flexion

During knee flexion, the IAR moves posteriorly due to the combination of rolling and gliding of the femoral condyles on the tibial plateau.