| Median eminence | |
|---|---|
 Median eminence is 'ME', at bottom-center, in light-green | |
| Details | |
| Identifiers | |
| Latin | eminentia mediana hypothalami |
| MeSH | D008473 |
| NeuroNames | 402 |
| NeuroLex ID | birnlex_925 |
| TA98 | A14.1.08.409 |
| TA2 | 5784 |
| FMA | 74634 |
| Anatomical terms of neuroanatomy | |
Themedian eminence is generally defined as the portion of the ventralhypothalamus from which theportal vessels arise.[1] The median eminence is a small swelling on thetuber cinereum, posterior to and on top of thepituitary stalk; it lies in the area roughly bounded on its posterolateral region by thecerebral peduncles, and on its anterolateral region by theoptic chiasm.
As one of the seven areas of the brain devoid of ablood–brain barrier,[2] the median eminence is acircumventricular organ havingpermeablecapillaries.[3][4][5][6] Its main function is as a gateway for release ofhypothalamichormones,[7] although it does share contiguousperivascular spaces with the adjacent hypothalamicarcuate nucleus, indicating a potential sensory role.[4][8]
The median eminence is a part of thehypothalamus from whichregulatory hormones are released.[2][7] It is integral to thehypophyseal portal system, which connects the hypothalamus with thepituitary gland. Thepars nervosa (part of the posterior pituitary gland) is continuous with the median eminence via theinfundibular stalk.Parvocellular neurosecretory cells from the hypothalamus terminate in the median eminence.[9]
The median eminence is the structure where secretions of the hypothalamus (releasing and inhibiting hormones) regulatory hormones, known as "hypophysiotropic hormones") collect before entering the portal system emptying into the general circulation.[2][7] Such hypophysiotropic hormones include: CRF (corticotropin-releasing factor), GnRH (gonadotropin-releasing hormone), TRH (thyrotropin-releasing hormone), GHRH (growth hormone-releasing hormone), and DA (dopamine).[7] These hypophysiotropic hormones stimulate or inhibit the release of hormones from theanterior pituitary.[7] Further, anatomical evidence exists for bidirectional communication between the median eminence and thearcuate andventromedial nucleus of the hypothalamus.[4][8]
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