The median eminence is part of the inferior boundary for the hypothalamus

Hypothalamus

The Hypothalamus is a portion of the brain that contains a number of small nuclei with a variety of functions...

 part of the human brain

Brain

The brain is the center of the nervous system in all vertebrate and most invertebrate animals—only a few primitive invertebrates such as sponges, jellyfish, sea squirts and starfishes do not have one. It is located in the head, usually close to primary sensory apparatus such as vision, hearing,...

. A small swelling on the tuber cinereum

Tuber cinereum

The tuber cinereum is a hollow eminence of gray matter situated between the mammillary bodies and the optic chiasm. The tuber cinereum is part of the hypothalamus.-Structure:...

 posterior to the infundibulum

Infundibulum

An infundibulum is a funnel-shaped cavity or organ.* Lungs: The alveolar sacs of the lungs from which the air chambers open are called infundibula...

 - atop the pituitary stalk - the median eminence lies in the area roughly bounded on its posterolateral region by the cerebral peduncle

Cerebral peduncle

Mainly, the three common areas that give rise to the cerebral peduncles are the cortex, the spinal cord and the cerebellum. The cerebral peduncle, by most classifications, is everything in the mesencephalon except the tectum. The region includes the midbrain tegmentum, crus cerebri and pretectum...

s, and on its anterolateral region by the optic chiasm

Optic chiasm

The optic chiasm or optic chiasma is the part of the brain where the optic nerves partially cross...

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The median eminence is one of the seven areas of the brain devoid of a blood-brain barrier

Blood-brain barrier

The blood–brain barrier is a separation of circulating blood and the brain extracellular fluid in the central nervous system . It occurs along all capillaries and consists of tight junctions around the capillaries that do not exist in normal circulation. Endothelial cells restrict the diffusion...

. It is sometimes considered one of the circumventricular organs

Circumventricular organs

Circumventricular organs are so named because they are positioned at distinct sites around the margin of the ventricular system of the brain.They are among the few sites in the brain which have an incomplete blood–brain barrier...

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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

Hypophyseal portal system

The hypophyseal portal system is the system of blood vessels that link the hypothalamus and the anterior pituitary in the brain.It allows endocrine communication between the two structures. It is part of the hypothalamic-pituitary-adrenal axis. The anterior pituitary receives releasing and...

, which connects the hypothalamus

Hypothalamus

The Hypothalamus is a portion of the brain that contains a number of small nuclei with a variety of functions...

 with the anterior lobe of the pituitary gland

Pituitary gland

In vertebrate anatomy the pituitary gland, or hypophysis, is an endocrine gland about the size of a pea and weighing 0.5 g , in humans. It is a protrusion off the bottom of the hypothalamus at the base of the brain, and rests in a small, bony cavity covered by a dural fold...

. Parvocellular neurons from the hypothalamus terminate in the median eminence of the hypothalamus. Specifically, 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.