- Diencephalon 341
Hypothalamus: Nuclei
■ Within the hypothalamus, from medial to lateral, are
the periventricular, intermediate, and lateral zones.
■ Both the periventricular and intermediate zones are
highly cellular whereas the lateral zone contains a
high degree of white matter fi bers.
■ Th e anteromedial hypothalamus is involved in
parasympathetic activity whereas the posterolateral
hypothalamus is involved in sympathetic activity.
■ Th e anterior (aka chiasmatic) group encompasses the
region above and anterior to the optic chiasm and
optic tract.
■ Th e middle (aka tuberal) group encompasses the
region between the optic chiasm and mammillary
bodies (ie, the region above the tuber cinereum).
■ Th e posterior (aka mammillary) group encompasses
the mammillary bodies and the region above them.Hypothalamus: Tracts
■ Th e magnocellular neurons of the paraventricular
and supraoptic nuclei project to the capillary plexus
of the neurohypophysis via the
hypothalamohypophysial tract.
■ Th e paraventricular and supraoptic nuclei release the
hormones vasopressin (aka antidiuretic hormone
[ADH]) and oxytocin.
■ Th e epithelial-cell–fi lled adenohypophysis releases
the following hormones into the general circulation
via hypophysial veins: follicle-stimulating hormone,
luteinizing hormone, adrenocorticotropic hormone,
thyroid-stimulating hormone, prolactin, growth
hormone, and melanocyte-stimulating hormone.
Th e hypothalamus controls the release of the
aforementioned hormones via a variety of
parvocellular neurons, the most notable of which is
the arcuate (aka infundibular) nucleus.