American Academy of Professional Coders (AAPC) Practice Exam

What type of muscle tissue is striated and performs rhythmic contractions?

1. Skeletal muscle

2. Cardiac muscle

3. Smooth muscle

4. Connective tissue

The correct answer is: Cardiac muscle

Cardiac muscle is the type of muscle tissue that is striated and performs rhythmic contractions. This type of muscle is found exclusively in the heart, where it plays a critical role in pumping blood throughout the body. Cardiac muscle fibers are unique because they not only have striations—similar to skeletal muscle—but they are also interconnected through specialized structures called intercalated discs. These discs allow for the rapid transmission of electrical impulses, facilitating coordinated contractions that are essential for maintaining a steady heart rhythm. In contrast, skeletal muscle is also striated, but it is under voluntary control and does not have the intrinsic rhythmic contraction capabilities that cardiac muscle does. Smooth muscle, on the other hand, is not striated and is responsible for involuntary movements in various organs, such as the intestines and blood vessels. Connective tissue serves a supportive role in the body and does not contract. Thus, the distinguishing features of cardiac muscle—its striated appearance and ability to contract rhythmically—make it the correct answer to the question.