Forebrain is further categorized into two parts, telencephalon and diencephalon. Within the forebrain’s diencephalon is the hypothalamus located. Between the midbrain and thalamus, hypothalamus is present.

Hypothalamus in humans is very small like the almond and consist of nucleus. Hypothalamus comprises of three regions the posterior, anterior and tuberal. Hypothalamus posterior region consist of lateral and medial areas. Within the medial region is the posterior nucleus and mammillary body and in the lateral area is the lateral nucleus posterior part.

Hypothalamus anterior region also consists of lateral and medial areas. The tuberal lateral nuclei and its tuberal part is present in lateral region. Hypothalamus nucleus is ventromedial and the nuclei is dorsomedial. Hypothalamus anterior region comprises of medial, lateral and preoptic areas. Preoptic nucleus is found in the preoptic area.

The anterior part of the hypothalamic nuclei consist of lateral preoptic nucleus, supraoptic nucleus of the lateral area. The hypothalamic nuclei present in the medial area are the anterior hypothalamic nucleus, supraoptic nucleus, medial preoptic nucleus, paraventricular nucleus and suprachiasmatic nucleus. For the autonomic nervous system, hypothalamus is the prime center. It is also called as endocrine gland.

Hypothalamic nuclei liberates certain hormone, which will exert its effect on the anterior pituitary gland, which will secrete hormone’s and have an impact on other organs and gland. There are hormones which are known as neurohypophysial hormones, which are produced from neurohypophysis axon terminal.