Hypothalamic–pituitary–thyroid axis control over the hypothalamus as well as anterior pituitary, thus controlling the release of both TRH from hypothalamus and TSH from anterior pituitary gland. The HPA, HPG, and HPT axes are three pathways in which the hypothalamus and pituitary direct neuroendocrine function. Thyroid homeostasis results from a multi-loop feedback system that is found in virtually all higher vertebrates. Proper function of thyrotropic feedback control is indispensable for growth, differentiation, reproduction and intelligence. Very few animals (e.g. axolotls and sloths) have impaired thyroid homeostasis that exhibits a very low set-point that is assumed to underlie the metabolic and ontogenetic anomalies of
Pituitary apoplexy one of the nerves. In half of these cases, the oculomotor nerve (the third cranial nerve), which controls a number of eye muscles, is affected. This leads to diagonal double vision and a dilated pupil. The fourth (trochlear) and sixth (abducens) cranial nerves are located in the same compartment and can cause diagonal or horizontal double vision, respectively. The oculomotor nerve is predominantly affected as it lies closest to the pituitary. The cavernous sinus also contains the carotid artery, which supplies blood to the brain; occasionally, compression of the artery can lead to one-sided weakness and other symptoms of stroke.