Human Anatomy & Biomechanics Flashcards

Which spinal region has the greatest range of rotation (axial rotation)?

Answer: Thoracic spine

The thoracic spine allows the greatest axial rotation due to its rib cage attachment and facet joint orientation.

The 'neutral spine' position in ergonomics refers to:

Answer: Preservation of the natural lordotic and kyphotic curves

Neutral spine preserves the natural S-curve of the spine, minimizing compressive and shear forces on intervertebral discs.

Which muscle group is primarily responsible for maintaining upright posture against gravity?

Answer: Erector spinae

The erector spinae muscles run along the spine and continuously contract to counteract gravitational forward flexion.

A worker repeatedly rotates the forearm so the palm faces upward. This motion is called:

Answer: Supination

Supination is the rotation of the forearm that turns the palm upward or anteriorly.

Which joint type allows the greatest freedom of movement in multiple planes?

Answer: Ball-and-socket joint

Ball-and-socket joints (like the hip and shoulder) allow movement in all three planes: flexion/extension, abduction/adduction, and rotation.

Intradiscal pressure in lumbar discs is HIGHEST during which posture?

Answer: Sitting with forward lean and no support

Unsupported forward-leaning seated postures dramatically increase intradiscal pressure due to combined compression and flexion forces.

The 'moment arm' in biomechanics refers to:

Answer: The perpendicular distance from a joint axis to the line of force

The moment arm is the perpendicular distance from the axis of rotation to the applied force, determining the torque produced.