There are three muscles located in the anterior compartment of the upper arm â biceps brachii, coracobrachialis and brachialis. They are all innervated by the musculocutaneous nerve. A good memory aid for this is BBC â biceps, brachialis, coracobrachialis.
Calcitonin is a hormone secreted by the thyroid gland that reduces the concentration of blood calcium level when it has risen to an above normal level. This polypeptide hormone is made up of 32 amino acids and is produced mainly by the parafollicular cells (also known as C cells) of the thyroid gland.
So, calcitonine primarily lowers blood-calcium level, and absorption of calcium into the bones is one way to reach that goal. Absorbing calcium into the bones certainly is not the purpose of calcitonine, for it stimulates excretion of calcium too. Due to the action of calcitonine, the increased blood-calcium level decreases, inhibiting calcitonine release and stimulating secretion of two other calcium-hormones; PTH and calcitriol.