304 Neuroanatomy: Draw It to Know It
Know-It Points
Basal Ganglia: Anatomy
■ Th e caudate nucleus lies along the lateral wall of the
lateral ventricle.
■ Th e lens-shaped lentiform nucleus subdivides into the
putamen, laterally, and the globus pallidus, medially.
■ Th e internal capsule lies in between the lentiform
nucleus and the head of the caudate, anteriorly, and
the lentiform nucleus and the thalamus, posteriorly.
■ Th e putamen and head of the caudate are connected
at the nucleus accumbens.
■ Th e lateral medullary lamina separates the putamen
and the globus pallidus.
■ Th e medial medullary lamina subdivides the globus
pallidus into an internal (or medial) segment and an
external (or lateral) segment.Basal Ganglia: Nomenclature
■ Th e term corpus striatum comprises the caudate,
putamen, and globus pallidus.
■ Th e caudate nucleus divides into a head, body, and tail.
■ Striations connect the caudate and the putamen;
thus, collectively, they are the striatum.
■ Th e pale appearance of the globus pallidus gives it its
name: pallidum.
■ Th e subthalamic nucleus and substantia nigra are
functionally but not developmentally associated with
t h e b a s a l g a n g l i a.Direct & Indirect Pathways: Anatomy (Advanced)
■ Field H lies medial to the subthalamic nucleus and
inferior to the zona incerta.
■ Field H1 lies in between the thalamus and zona incerta.
■ Field H2 lies lateral to the zona incerta and medial to
the internal capsule.
■ Th e ansa lenticularis originates in the globus pallidus
internal segment, projects inferomedially, passes
beneath the subthalamic nucleus, and then passes
through Field H and Field H1 to enter the thalamus.
■ Th e lenticular fasciculus projects from the internal
segment of the globus pallidus through Fields H2,
H, and H1 to enter the thalamus.
■ Where the ansa lenticularis and the lenticular
fasciculus run together in Field H1, they are
collectively called the thalamic fasciculus.
■ Th e subthalamic fasciculus refers to projections
between the globus pallidus and subthalamic
nucleus.