NeuroNames hier-385 TA A14.1.08.409 | NeuroLex ID Median eminence FMA 74634 | |
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Latin eminentia mediana hypothalami MeSH A08.186.211.730.385.357.352.435.249 | ||
The median eminence is part of the inferior boundary of the hypothalamus in the human brain. A small swelling on the tuber cinereum posterior to the infundibulum – atop the pituitary stalk – the median eminence lies in the area roughly bounded on its posterolateral region by the cerebral peduncles, and on its anterolateral region by the optic chiasm.
The median eminence is one of the seven areas of the brain devoid of a blood–brain barrier. It is sometimes considered one of the circumventricular organs.
Physiology
The median eminence is a part of the hypothalamus from which regulatory hormones are released. It is of great physiological importance, as it is integral to the hypophyseal portal system, which connects the hypothalamus with the pituitary gland. The pars nervosa (part of the posterior pituitary gland) is continuous with the median eminence of the hypothalamus via the infundibular stalk. Parvocellular neurons from the hypothalamus terminate in the median eminence of the hypothalamus. To be specific, it is in the median eminence that the secretions of the hypothalamus (releasing and inhibiting regulatory hormones, known as "hypophysiotropic hormones") collect before entering the portal system. Such hypophysiotropic hormones include: CRF (corticotropin-releasing factor), GnRH (gonadotropin-releasing hormone), TRH (thyrotropin-releasing hormone), GHRH (growth hormone-releasing hormone), and DA (dopamine). These hypophysiotropic hormones go on to stimulate or inhibit the release of hormones from the anterior pituitary.