Thyroid (IMAGE) University of Texas at Austin Caption The thyroid is a gland in the neck producing hormones that control the body's metabolic rate, as well as heart and digestive function, muscle control, brain development, mood and bone maintenance. Credit Melanie Connolly Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.