Week 11 Quiz

During a curl, the biceps brachii pulls the radius up toward the scapula while the scapula stays put. Where is the biceps brachii's insertion?

Select one.

• On the radius, the bone that moves
• On the scapula, the bone that stays fixed
• In the belly, the thick middle of the muscle
• At the elbow joint, the pivot of the curl

When the biceps brachii flexes the forearm, the angle between the forearm and the arm at the elbow decreases.

True or false.

• True
• False

When the triceps brachii straightens the arm, which role does the biceps brachii play in that movement?

Select one.

• Agonist, because it is always the prime mover of the arm
• Antagonist, because it produces the opposite action and relaxes
• Fixator, because it holds the scapula steady for the triceps
• Synergist, because it pushes the forearm straight with the triceps

Someone holds a bag still at chest height. The biceps brachii is tense, but the elbow's angle does not change. Which kind of contraction is this?

Select one.

• Concentric, because the muscle is doing work
• Eccentric, because the bag is pulling down on the arm
• Isometric, because tension develops without a change in angle
• Isotonic, because the muscle is holding a load

Using the muscle-naming logic, which two kinds of clue does the name rectus femoris carry?

Select one.

• Size and shape
• Number of origins and action
• Attachments and size
• Fiber direction and location

When a person rises onto the toes, the body's weight sits between the pivot and the muscle's pull. Which lever class is this?

Select one.

• Second class, with the load in the middle
• First class, with the fulcrum in the middle
• Third class, with the effort in the middle
• No class, because the foot is not a bone

In Dataset H, the illustrative forearm lever, a 60 N load sits 36 cm from the elbow and the biceps brachii inserts 4 cm from the elbow. Using effort × effort arm = load × load arm, what effort must the biceps pull to hold the load?

Select one.

• 2,160 N
• 540 N
• 240 N
• 6.7 N

On the forearm lever, the biceps brachii must pull nine times the load it holds. What does the arm gain in return for that force disadvantage?

Select one.

• Strength, because the biceps is the body's strongest lever
• Nothing, because the filaments shorten and waste the pull
• Stability, because the elbow is a first-class lever
• Speed and range of motion at the hand, far from the elbow

Which of these muscles has extension of a joint as its main action? Select every one that does.

Select every option that applies.

• Triceps brachii
• Biceps brachii
• Gluteus maximus
• Tibialis anterior
• Quadriceps femoris
• Rectus abdominis

The tibialis anterior lifts the front of the foot toward the shin. What is this movement called?

Select one.

• Plantar flexion
• Supination
• Dorsiflexion
• Abduction