352 Neuroanatomy: Draw It to Know It
Hypothalamus: Nuclei
Here, we will draw the hypothalamic zones, nuclear
groups, and the most prominent hypothalamic nuclei.
First, draw the hypothalamic zones in coronal section.
Draw the third ventricle and the adjacent hypothalamus
and above it label the thalamus. Next, from medial to
lateral within the hypothalamus, label the periventricu-
lar, intermediate, and lateral zones. Indicate that the
column of the fornix lies in between the intermediate
and lateral zones and distinguishes them. Now, indicate
that the periventricular and intermediate zones are oft en
collectively referred to as the medial zone (as we will
routinely refer to them, here); however, the medial zone
is sometimes used to refer to the intermediate zone, only,
instead. Both the periventricular and intermediate zones
are highly cellular whereas the lateral zone contains a
high degree of white matter fi bers.
Now, we will draw hypothalamic nuclear groups.
Draw a sagittal outline of the hypothalamus: along
the inferior border, include the pituitary stalk and mam-
millary bodies and in between them label the tuber
cinereum; then, label the anterior border of the hypo-
thalamus as the lamina terminalis and antero-superiorly
draw the anterior commissure and antero-inferiorly draw
the optic chiasm. Next, although it is an oversimplifi ca-
tion, include the following important physiologic prin-
ciple: the anteromedial hypothalamus is involved in
parasympathetic activity (eg, satiety, sleep, and heat
dissipation to decrease body temperature) and the poste-
rolateral hypothalamus is involved in sympathetic activ-
ity (hunger, wakefulness, and heat conservation to
increase body temperature).^3 , 16 Now, label the anterior
(aka chiasmatic) group as encompassing the region above
and anterior to the optic chiasm and optic tract; then,
label the middle (aka tuberal) group as encompassing
the region between the optic chiasm and mammillary
bodies (ie, the region above the tuber cinereum); and
then, label the posterior (aka mammillary) group as
encompassing the mammillary bodies and the region
above them.
Next, let’s draw the individual nuclei; begin with the
hypothalamic nuclei of the medial zone (the collective
periventricular and intermediate zones). First, draw the
anterior (chiasmatic) group nuclei: from inferior to supe-
rior, starting just above the optic chiasm, draw the supra-
chiasmatic, anterior, and paraventricular nuclei. Next, in
the preoptic region, label the medial preoptic nucleus in
front of the anterior nucleus. Th e preoptic nucleus devel-
ops as part of the telencephalon but is anatomically and
functionally related to the hypothalamus, so it is com-
monly included as part of the hypothalamus. Note that
the preoptic region is oft en distinguished from the ante-
rior group as its own nuclear group. Now, draw the
middle (tuberal) group nuclei: from inferior to superior,
starting along the tuber cinereum, draw the infundibular
(aka arcuate) nucleus and then the ventromedial and
dorsomedial nuclei. Next, draw the posterior (mammil-
lary) group nuclei: fi rst, within the mammillary body,
draw the medial mammillary nucleus, and then above it,
draw the posterior nucleus. Finally, extending through
the inferior aspect of the middle (tuberal) and posterior
(mammillary) groups, draw the medial aspect of the
tuberomammillary nucleus.
Now, recreate a sagittal view of the hypothalamus so
we can draw the lateral zone hypothalamic nuclei. First,
anteriorly, in the preoptic region, draw the lateral preop-
tic nucleus. Th en, above the optic tract, draw the supraop-
tic nucleus. Note that many texts list this nucleus as lying
within the medial zone of the hypothalamus rather than
the lateral zone. Next, draw the lateral aspect of the
tuberomammillary nucleus along the inferior aspect of
the hypothalamus extending through the middle and
posterior groups. Now, draw a small nucleus in the pos-
terior aspect of the tuberal region, called the lateral
tuberal nucleus. Th en, label the lateral mammillary
nucleus. And fi nally, delineate the lateral hypothalamic
area, which spans from the posterior optic chiasm to the
posterior end of the hypothalamus; it, most notably,
contains the medial forebrain bundle.^3 , 6 – 8 , 17 – 21