Which glands regulate blood calcium and phosphorus levels for proper functioning of the nervous and muscular systems?

The parathyroid glands are specialized endocrine glands located near the thyroid gland in the neck and play a critical role in regulating calcium and phosphorus levels in the body. They produce parathyroid hormone (PTH), which is essential for maintaining the balance of these minerals. PTH stimulates the release of calcium from bones, increases absorption of calcium in the intestines, and enhances reabsorption of calcium in the kidneys. This regulation is vital for muscle contraction and proper nerve function, as both of these systems rely heavily on calcium dynamics.

While the thyroid glands are involved in metabolism and influence calcium levels via calcitonin, their primary function is not to regulate blood calcium levels directly but to respond to high calcium levels by lowering it. The adrenal glands are primarily associated with stress response and metabolism of fats, proteins, and carbohydrates. The pituitary glands have a wide range of functions including hormone regulation, but they do not directly control blood calcium or phosphorus levels. Thus, the parathyroid glands are the correct answer as they are specifically designed to manage these crucial mineral levels that are directly linked to the nervous and muscular systems' proper functioning.