Your thyroid is a gland at the front of your neck beneath your voice box (larynx). A healthy thyroid is a little larger than a quarter. It usually cannot be felt through the skin.

The thyroid has two parts (lobes). A thin piece of tissue (the isthmus) separates the lobes.

The thyroid makes hormones:

• Thyroid hormone: Thyroid hormone is made by thyroid follicular cells. It affects heart rate, blood pressure, body temperature, and weight.
  
  
• Calcitonin: Calcitonin is made by C cells in the thyroid. It plays a small role in keeping a healthy level of calcium in the body.

Four or more tiny parathyroid glands are behind the thyroid. They are on its surface. They make parathyroid hormone, which plays a big role in helping the body maintain a healthy level of calcium.

The pictures show the front and back of the thyroid.

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