Where is cardiac muscle primarily located?

Cardiac muscle is primarily located in the heart, which is its exclusive site of function. This specialized muscle tissue is unique to the heart's structure and plays a critical role in pumping blood throughout the body. The cells of cardiac muscle are interconnected, allowing for coordinated contractions that are essential for maintaining a consistent heartbeat.

The other options reference locations that do not contain cardiac muscle. While skeletal muscle is found throughout the body and smooth muscle serves various functions in organs such as the liver and lungs, cardiac muscle is distinct in its singular presence within the heart itself. This specialized adaptation is vital for the heart's ability to function effectively as a pump, making the pinpointing of its location significant in understanding its role in the circulatory system.