What is the difference between muscle fascicle and muscle bundle? , the muscle bundle is shown to be as a bundle of fascicles, but in most web definitions I've seen, the two terms are used interchangeably. What is the correct name for the part labeled "muscle bundle" if there are in fact no distinctions between bundle and fascicle?

**Short answer**
Muscle fascicles are the building blocks of skeletal muscle.

**Background**
Skeletal muscle, or striated muscle is composed of many units called muscle fascicles. The fascicles are bound together by a type of connective tissue called fascia.

Fascicles in skeletal muscle are composed of muscle cells, called mycocytes. These cells are referred to as muscle fibers in skeletal muscle. Myocytes contain small strands called myofibrils, which are the contractile elements in the muscle cells. The myofibrils move as skeletal muscle contracts.

Putting it all back together, myofibrils are the contractile elements in muscle cells (muscle fibers); muscle fibers make-up muscle fascicles; and muscle fascicles are bound together by fascia to compose the skeletal muscle.

Hence the part labeled 'muscle bundle' is a **muscle** , made out of a **bundle of fascicles**.

Source: Penn Medicine