336 Neuroanatomy: Draw It to Know It
Thalamic Arteries ( Advanced )
In this diagram, we will draw the thalamic arterial supply.
First, on the left -hand side of the page, draw two outlines
of the thalamus: we will use these outlines to show the
arterial territories of the thalamus. Label one as dorsal
and the other as ventral to distinguish the variation
in thalamic arterial supply at diff erent heights. Also,
include the anterior–posterior and medial–lateral planes
of orientation.
On the right-hand side of the page, we will draw the
arteries, themselves. First, draw the basilar artery and
show that it bifurcates into the bilateral PCAs. Next,
draw an axial cut through the left internal carotid artery.
Th en, connect the left internal carotid artery and left
PCA with the posterior communicating artery.
Now, let’s show the vessels that supply the thalamus.
Emanating from the posterior communicating artery,
draw the thalamotuberal artery. Th e thalamotuberal
artery has a few alternate names, which although cum-
bersome help us to understand its arterial distribution;
they include the following : the anterior thalamoperfo-
rating artery, premammillary artery, and polar artery.
Indicate that within the thalamus, both dorsally as well
as ventrally, the thalamotuberal artery supplies the ante-
rior thalamus: specifi cally, it supplies the ventroanterior
nucleus, ventrolateral nucleus, and the anterior portion
of the medial thalamic nuclei.
Next, we will draw the medial branch of the poste-
rior choroidal artery. Show that it emerges from the
PCA lateral to the posterior communicating artery. Th e
medial posterior choroidal artery supplies the medial
thalamus: most notably, the medial posterior pulvinar
and medial geniculate body (of the metathalamus).
Indicate that dorsally, its arterial supply extends anteri-
orly, whereas ventrally, its distribution is restricted to
being more posterior.
Now, lateral to the medial posterior choroidal artery,
draw the lateral posterior choroidal artery, which sup-
plies the lateral pulvinar, dorsomedial thalamic nucleus,
and lateral geniculate body (of the metathalamus). Show
that dorsally its supply is restricted to the medial poste-
rior thalamus, whereas ventrally its supply extends out
laterally.
Next, show that the thalamoperforating arteries
emanate from the PCA medial to the posterior commu-
nicating artery. Like the thalamotuberal artery, the thal-
amoperforating arteries have several alternate names;
they include the following : the thalamic-subthalamic
arteries, paramedian arteries, posterior inferior optic
arteries, and deep interpeduncular profunda arteries.
Th e thalamoperforating arteries supply the medial por-
tion of the thalamus. Show that dorsally, the medial
extent of their supply ends at the medial posterior chor-
oidal artery territory, whereas ventrally, their supply
extends to the medial edge of the thalamus. Much atten-
tion is given to the anatomic variant wherein a common
stem, the artery of Percheron, emanates from one PCA
and provides thalamoperforating branches to the bilat-
eral medial thalamic and extra-thalamic thalamoperfo-
rating territories.
Now, in between the posterior choroidal arteries,
draw the thalamogeniculate arteries, which supply the
lateral thalamus and help supply the geniculate bodies.
Dorsally, show that their supply extends posteriorly,
whereas ventrally, show that it extends anteriorly.
In addition to supplying the thalamus and metathala-
mus, the thalamic arteries also help supply many other
diencephalic structures, such as the hypothalamus, sub-
thalamus, optic tracts, and internal capsule; they also
help supply certain upper brainstem structures, as well as
the choroid plexus and hippocampus.^2 , 4 , 12 – 16