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Basal Nuclei and Extrapyramidal Motor System 121<br />
Fornix<br />
Corpus callosum<br />
Lateral<br />
ventricle<br />
Caudate<br />
nucleus<br />
Thalamus<br />
Putamen<br />
Globus<br />
pallidus<br />
Lentiform<br />
nucleus<br />
Internal<br />
capsule<br />
VA<br />
VL CM<br />
CM<br />
VL<br />
VA<br />
Insula<br />
Third<br />
ventricle<br />
Optic tract<br />
Substantia nigra<br />
Amygdala<br />
Mamillary<br />
body<br />
Hippocampus<br />
Subthalamic<br />
nucleus<br />
Lateral ventricle<br />
Figure 16-1 Coronal section through the midthalamus at the level of the mammillary bodies. The basal nuclei (ganglia)<br />
are all prominent at this level and include the striatum and lentiform nucleus. The subthalamic nucleus and substantia<br />
nigra are important components of the striatal motor system. CM, centromedian nucleus; VA, ventral anterior nucleus;<br />
VL, ventral lateral nucleus.<br />
3. Globus pallidus<br />
4. Subthalamic nucleus<br />
5. Substantia nigra (i.e., pars compacta and pars reticularis)<br />
6. Thalamus (ventral anterior, ventral lateral, and centromedian nuclei)<br />
B. Figure 16-5 shows the major afferent and efferent connections of the striatal system.<br />
C. Neurotransmitters are seen in Figure 16-6.<br />
III<br />
Clinical Correlation<br />
A. Parkinson Disease. This is a degenerative disease that affects the substantia nigra and its<br />
projections to the striatum.<br />
1. Results of Parkinson disease are a depletion of dopamine in the substantia nigra and striatum<br />
as well as a loss of melanin-containing dopaminergic neurons in the substantia nigra.<br />
2. Clinical signs are bradykinesia, stooped posture, shuffling gait, cogwheel rigidity, pill-rolling<br />
tremor, and masked facies. Lewy bodies are found in the melanin-containing neurons of the substantia<br />
nigra. Progressive supranuclear palsy is associated with Parkinson disease.<br />
3. Treatment has been successful with L-dopa. Surgical intervention includes pallidotomy (rigidity)<br />
and ventral thalamotomy (tremor).
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