Anatomy & Biomechanics Flashcards

Which of the following best describes the moment arm for the Achilles tendon at the ankle joint?

Answer: The perpendicular distance from the ankle axis to the line of tendon force

A moment arm is always the perpendicular distance from the joint axis to the line of action of the force, determining mechanical advantage.

In a transfemoral amputee, which hip motion is most limited by the absence of the distal limb segment?

Answer: Terminal swing extension

Without the inertia of the distal limb and knee extension, terminal swing hip extension is reduced, often shortening step length.

The obliquity of the metatarsophalangeal break line affects prosthetic foot design primarily by influencing:

Answer: Roll-over shape and mediolateral stability during push-off

The MTP break line angle determines how smoothly load transfers across the forefoot, affecting roll-over shape and lateral stability.

Spasticity in the lower extremity is a velocity-dependent increase in which reflex?

Answer: Tonic stretch reflex

Spasticity is defined as a velocity-dependent increase in tonic stretch reflexes, resulting from upper motor neuron lesions.

Which of the following joints is considered the 'key link' in the kinetic chain for transferring force from the foot to the hip?

Answer: Knee joint

The knee is considered the key link because it must both absorb shock and provide stability while transmitting forces between the ankle and hip.

Excessive lumbar lordosis in a transfemoral prosthetic user most commonly indicates:

Answer: Hip flexion contracture not accommodated by socket flexion

A hip flexion contracture that is not built into the socket as flexion bias forces the lumbar spine into compensatory lordosis.