Human Anatomy & Biomechanics Flashcards

The lumbar spine consists of how many vertebrae?

Answer: Five (L1–L5)

The lumbar spine contains five vertebrae (L1–L5), which bear the greatest compressive loads and are most vulnerable to work-related injury.

The carpal tunnel is bounded on three sides by carpal bones and on the palmar surface by which structure?

Answer: Flexor retinaculum (transverse carpal ligament)

The flexor retinaculum (transverse carpal ligament) forms the roof of the carpal tunnel on the palmar side, and tightening of this structure compresses the median nerve.

In seated workstation ergonomics, the 'hip angle' is defined as the angle between:

Answer: The trunk and the thigh

The hip angle is formed between the trunk and the thigh; a range of approximately 90–110° is recommended for a neutral, low-stress seated posture.

Which spinal structure primarily absorbs compressive forces and allows movement between adjacent vertebrae?

Answer: Intervertebral disc

The intervertebral disc, composed of the nucleus pulposus and annulus fibrosus, acts as a hydraulic shock absorber between vertebral bodies.

Ulnar deviation of the wrist describes movement of the hand toward:

Answer: The little finger (ulnar) side

Ulnar deviation moves the hand toward the ulnar (little finger) side and is a posture commonly associated with elevated risk of carpal tunnel syndrome.

When a worker holds a load at arm's length rather than close to the body, the primary biomechanical effect on the lumbar spine is:

Answer: Increased spinal moment (torque) due to a greater moment arm

A longer moment arm multiplies the torque that spinal muscles must generate to maintain balance, greatly increasing lumbar compressive and shear forces.

Neutral wrist posture in ergonomic guidelines is typically defined as approximately:

Answer: 0–15° of extension with 0–5° of ulnar deviation

Neutral wrist posture (0–15° extension, minimal ulnar deviation) minimizes pressure on tendons and the median nerve within the carpal tunnel.