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.
In particular, calcitonin has the ability to decrease blood calcium levels at least in part by effects on two well-studied target organs: 1  Bone: Calcitonin suppresses resorption of bone by inhibiting the activity of osteoclasts, a cell type that digests bone matrix, releasing calcium and phosphorus into blood.