High-Yield Neuroanatomy 5e

Diencephalon 93
Ant. nuclear group
Internal medullary lamina
Mediodorsal nucleus
VA
VL
MD
L D
LP
VPL
VPM
Ventral tier nuclei
Lat. geniculate body
Medial geniculate body
Figure 11-1 Major thalamic nuclei and their connections. A. Dorsolateral aspect and major nuclei. LD, lateral dorsal
nucleus; LP, lateral posterior nucleus; MD, medial dorsal nucleus; VA, ventral anterior nucleus; VL, ventral lateral nucleus;
VPL, ventral posterior lateral nucleus; VPM, ventral posterior medial nucleus.
D. The pulvinar is the largest thalamic nucleus. It has reciprocal connections with the association cortex
of the occipital, parietal, and posterior temporal lobes. It receives input from the lateral and medial geniculate
bodies and the superior colliculus. It plays a role in the integration of visual, auditory,
and somesthetic input. Destruction of the pulvinar may result in sensory dysphasia.
E. Ventral Tier Nuclei
1. The ventral anterior nucleus receives input from the globus pallidus and substantia nigra. It
projects diffusely to the prefrontal cortex, orbital cortex, and premotor cortex (Brodmann area 6).
2. The ventral lateral nucleus receives input from the cerebellum (dentate nucleus), globus pallidus,
and substantia nigra. It projects to the motor cortex (Brodmann area 4) and the supplementary
motor cortex (Brodmann area 6).
3. The ventral posterior nucleus is the nucleus of termination of general somatic afferent (touch,
pain, and temperature) and special visceral afferent (taste) fibers. It has two subnuclei:
a. Ventral posterolateral nucleus receives the spinothalamic tracts and the medial lemniscus. It
projects to the somesthetic (sensory) cortex (Brodmann areas 3, 1, and 2);
b. Ventral posteromedial (VPM) nucleus receives the trigeminothalamic tracts and projects to
the somesthetic (sensory) cortex (Brodmann areas 3, 1, and 2). The gustatory (taste) pathway
originates in the solitary nucleus and projects via the central tegmental tract to the VPM and
thence to the gustatory cortex of the postcentral gyrus, of the frontal operculum, and of the
insular cortex. The taste pathway is ipsilateral.
4. The lateral geniculate body is a visual relay nucleus. It receives retinal input through the optic
tract and projects to the primary visual cortex (Brodmann area 17).
5. The medial geniculate body is an auditory relay nucleus. It receives auditory input through the
brachium of the inferior colliculus and projects to the primary auditory cortex (Brodmann areas 41
and 42).
F. The reticular nucleus of the thalamus surrounds the thalamus as a thin layer of γ-aminobutyric
acid (GABA)-ergic neurons. It lies between the external medullary lamina and the internal capsule.
It receives excitatory collateral input from corticothalamic and thalamocortical fibers. It projects
inhibitory fibers to thalamic nuclei, from which it receives input.