Answer
4.
They need to learn to control the diaphragm and the abdominal muscles. The internal intercostals are also important accessory muscles that help the singer to hold a note.
Work Step by Step
Singers talk about the epigastrium, but the epigastrium is not a muscle. The middle upper region of the nine part division of the abdominal cavity is called the epigastric region. When one is trying to hold a note for a long time or to sing a high note with power, the conjoined activity of the rectus abdominis and the diaphragm ( so-called epigastrium) is very important.