The muscles in the back of your tongue help you make certain sounds, like the letters k and hard g (like in the word go). Try saying these letters slowly, and you'll feel how the back of your tongue moves against the top of your mouth to create the sounds. The back of your tongue is important for eating as well.
The most common cause is a benign tumor in your pituitary gland, which is located under your brain. This tumor is not cancer. Because of the tumor, your body makes too much growth hormone. Once in a while, tumors in the pancreas, liver, or parts of the brain can cause high levels of growth hormone. That leads to higher levels of another hormone, called insulin-like growth hormone, which causes the symptoms you see.
Acromegaly is a very rare disorder caused, in most cases, by a tumor of the pituitary gland that produces too much growth hormone (GH). Nearly all pituitary tumors, including those that cause acromegaly, are benign, and not malignant. However, they can become quite large and expand beyond the normal confines of the pituitary gland. Rarely, acromegaly can be caused by a tumor located in other areas of the body. Changes in facial features in acromegaly.