Question

Which one of the following is correct pairing of a body part and muscle fibre that moves it?

• A. Heart wall - involuntary unstriated muscle
• B. Biceps of upper arm – smooth muscle fibres
• C. Iris – involuntary smooth muscle
• D. Abdominal wall – smooth muscle

Answer 1

The correct option is C Iris – involuntary smooth muscle

Cardiac muscle (heart muscle) is an involuntary,striated muscle that is found in the walls and histological foundation of the heart, specifically the myocardium.
The biceps are classified as skeletal muscles because they attach directly to the skeleton and they are voluntary that is they can be moved at our will.
The iris is made up of smooth muscle fibers that adjust pupil size. The human eyes exhibit several types of involuntary movement, such as the constriction of the pupil in bright light or the expansion of it in dim light.
Smooth muscle is found within the walls of our internal organs and structures such as the stomach and they are involuntary.