Human Anatomy and Biomechanics Flashcards

During the upward phase of a bicep curl, the biceps brachii is shortening while generating force. Which type of muscle contraction is occurring, and what is the role of the biceps brachii?

Answer: Concentric contraction, Agonist

A concentric contraction occurs when a muscle shortens under tension. The biceps brachii is the prime mover, or agonist, for elbow flexion, which is the primary movement in a bicep curl. Therefore, during the upward phase, the biceps brachii performs a concentric contraction and acts as the agonist.

A client is performing a lateral raise with dumbbells. This movement primarily occurs in which anatomical plane?

Answer: Frontal (Coronal) Plane

The frontal (or coronal) plane divides the body into anterior (front) and posterior (back) sections. Movements in this plane are side-to-side, such as abduction and adduction. A lateral raise involves shoulder abduction, moving the arms out to the sides, which is a classic frontal plane movement.

Which of the following describes the biomechanical role of the triceps brachii during the downward (lowering) phase of a traditional push-up?

Answer: Agonist performing an eccentric contraction

In a push-up, the triceps are a prime mover (agonist) for elbow extension (the upward phase). During the downward phase, gravity is pulling the body down. The triceps must lengthen under tension to control this descent. This is an eccentric contraction. Since the triceps are controlling the primary movement, they are still considered the agonist in this phase.

A client performing a squat exhibits a significant forward lean of the torso. From a biomechanical perspective, this compensation primarily increases the demands on which muscle group?

Answer: Erector Spinae

Leaning the torso forward during a squat increases the flexion moment at the hip and lumbar spine. To counteract this and prevent the torso from collapsing, the erector spinae muscles, which run along the spine, must work significantly harder to maintain spinal extension and stability.

When performing a standing cable wood chop, the rotational movement of the torso occurs in which plane of motion?

Answer: Transverse Plane

The transverse plane divides the body into superior (upper) and inferior (lower) halves. Rotational movements, such as twisting the torso in a wood chop exercise, occur within this plane.

During a lunge, the gluteus maximus is the prime mover for hip extension. The hamstrings assist in this motion. What is the functional role of the hamstrings in this scenario?

Answer: Synergist

A synergist muscle is one that assists the prime mover (agonist) in performing a specific joint action. In the case of hip extension during a lunge, the gluteus maximus is the agonist, and the hamstrings act as synergists to help produce the movement.