The hypothalamus is a functionally diverse region of the forebrain which exerts profound regulatory influences over physiological and behavioural processes essential for survival. It possesses extensive synaptic connections with other regions of the nervous system and is the region of the brain responsible for controlling the functional activity of the pituitary gland. An essential feature of its function is the ability to convert synaptic information to humoral signals that exert regulatory control over peripheral organ systems and to respond to the functional activity of the peripheral systems that it controls.

Keywords: biological timing; neuroendocrine regulation; homeostasis; reproduction

Figure 1.

The location of the hypothalamus in the ventral forebrain is illustrated in midsagittal and ventral exposures of the human brain. (a) The midsagittal exposure reveals the hypothalamus (marked with an asterisk) immediately in front of the midbrain flexure. This same exposure is shown at higher magnification in Figure 2a. (b) The ventral exposure reveals the three major superficial landmarks that mark the position of the hypothalamus in the ventral diencephalon. The most rostral portion is marked by the optic chiasm (OC), which is formed by the convergence of the optic nerves and gives rise to the optic tracts. The pituitary stalk (PS) lies immediately behind the chiasm in the tuberal hypothalamus. The pituitary has been removed from this specimen, revealing the central lumen, which is continuous with the third ventricle. The bilaterally paired mammillary bodies (MB) mark the caudal‐most extent of the hypothalamus.

Figure 2.

(a) The rostrocaudal extent of the hypothalamus, defined by the optic chiasm (OC) and mammillary body (MB), is shown in midsagittal exposure. (b) The internal structure of hypothalamus as revealed in a myelin‐stained transverse section passing through the level of the pituitary stalk. The homogeneous tissue on either side of the third ventricle (V3) constitutes the bilaterally paired cell masses that form the hypothalamus. The relative position of periventricular (P), medial (M) and lateral (L) columns are defined on the left side of the hypothalamus. OT, optic tract: F, fornix.


Further Reading

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Card, J Patrick(May 2001) Hypothalamus. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1038/npg.els.0000148]