308 Neuroanatomy: Draw It to Know It
Basal Ganglia: Anatomy
Here, we will draw the basal ganglia and its related struc-
tures in axial, coronal, and sagittal views. Note that
we will not be able to show all of the structures in each
view; however, through the combined views we will
draw the fundamental anatomy of the basal ganglia.
Also, note that the basal ganglia are more correctly
referred to as the basal nuclei because by defi nition a
ganglion is a neuronal aggregation within the peripheral
nervous system and the basal nuclei lie within the central
nervous system. Begin with an axial view. First, draw a
few orientational landmarks: along the medial aspect
of the diagram, anteriorly, draw the frontal horn of the
lateral ventricle; then, posteriorly, draw the body of the
lateral ventricle and the thalamus; next, along the lateral
edge of the diagram, draw the insula and then medial to
it, draw the claustrum.
Next, let’s include a few key basal ganglia structures.
Along the lateral wall of the frontal horn of the lateral
ventricle, label the head of the caudate. Th en, at the pos-
tero-lateral tip of the thalamus in the lateral wall of the
body of the lateral ventricle, draw the tail of the caudate.
Note that the body of the caudate is not visible at this
axial height. Now, in the center of the diagram, draw the
lens-shaped lentiform nucleus and subdivide it into the
putamen, laterally, and the globus pallidus, medially.
Early in development, the globus pallidus migrates into
the medial wall of the putamen—we can envision the
lentiform nucleus as a globus pallidus core surrounded
by a putaminal shell. Next, in between the lentiform
nucleus and the head of the caudate and thalamus, label
the internal capsule. Th en, in between the putamen
and the claustrum, label the external capsule, and in
between the claustrum and the insula, label the extreme
capsule.
Now, let’s draw a coronal view through the anterior
aspect of the basal ganglia. At the inferomedial aspect of
the diagram, draw the optic chiasm; then, along the supe-
rior aspect of the diagram, draw the corpus callosum; just
below it, draw the frontal horn of the lateral ventricle.
Next, draw the combined putamen and head of the cau-
date and show that they are connected at the base by
the nucleus accumbens. Th e nucleus accumbens is the
bridge that persists between the head of the caudate and
putamen aft er the anterior limb of the internal capsule
separates the head of the caudate from the putamen.
Now, beneath the nucleus accumbens, draw the basal
forebrain.
Next, draw another coronal view just posterior to the
previous section. To establish the anterior-posterior
plane of this diagram, inferiorly, draw the optic tract
and third ventricle; the hypothalamus immediately sur-
rounds the third ventricle. Next, draw the corpus callo-
sum and frontal horn of the lateral ventricle. Along
the lateral wall of the frontal horn, draw the head of the
caudate. Th en, draw the putamen, and medial to it, draw
the globus pallidus; show that the lateral medullary
lamina separates them. Note that the medial medullary
lamina subdivides the globus pallidus into an internal
(or medial) segment and an external (or lateral) segment.
Next, in between the lentiform nucleus and the caudate,
draw the internal capsule. Now, beneath the globus pal-
lidus, draw the basal forebrain and then draw the hori-
zontally oriented anterior commissure in between them.
Note that the globus pallidus actually extends beneath
the anterior commissure as the ventral pallidum (see
Drawing 18-2 ).
Lastly, let’s draw the basal ganglia in sagittal view.
First, draw the corpus callosum and the subjacent lateral
ventricular system: label the frontal horn, atrium, and
temporal horn divisions of the ventricular system. Next,
draw the caudate and label the head and body. Note that
the tail is not visible in this section. Th en, anteriorly,
draw the putamen and, posteriorly, draw the thalamus.
In between these structures, label the internal capsule,
and show that it funnels, inferiorly, into the cerebral
peduncle.