Thalamus

The thalamus is a gray cell mass about 4 cm long, lying on each side of the third ventricle, fused together with the contralateral through a thin junction, the interthalamic mass. The thalamus reaches the third ventricle caudally below and the foramen of Monro anteriorly. The posterior part is broader (pulvinar) and overhangs the quadrigeminal plate. Below the thalamus is the lateral geniculate body; infero-me-dially the medial geniculate body is separated from it by the brachium of the superior colliculus. Below the thalamus laterally is the subthalamic nucleus, and medially the red nucleus. Superiorly, the thalamus is covered by a layer of white matter and separated from the caudate nucleus by the stria terminalis and the thalamostriate vein. The lateral aspect of the superior surface forms part of the floor of the lateral ventricle, and is covered by the tela choroidea, which separates the thalamus from the fornix.

The thalamus is mainly composed of gray matter and many nuclei have been described inside it. The spatial distribution of these nuclei is rather complex, and only the gross structure is reported in this chapter. They are subdivided into three main groups: anterior nuclear group, medial nuclear group, and lateral nuclear group. The posterior part of the thalamus is the pulvinar. The three groups are separated by the internal medullary lamina, which has a "Y" shape.

Claustrum

Claustrum

Basal amygdaloid nucleus
Lateral amygdaloid nucleus

Posterior limb of internal capsule

Anterior limb of internal capsule

Putamen

Basal amygdaloid nucleus

Cortical amygdaloid nucleus

Caudate nucleus

Pulvinar

Lateral geniculate body

Anterior limb of internal capsule

Putamen

Basal amygdaloid nucleus

Cortical amygdaloid nucleus

Posterior limb of internal capsule

Caudate nucleus

Pulvinar

Lateral geniculate body

Body of caudate nucleus

Head of caudate nucleus

Ventral lateral thalamic nucleus

Globus pallidus, ,, pars medialis

Anterior commissure

Body of caudate nucleus

Head of caudate nucleus

Ventral lateral thalamic nucleus

Globus pallidus, ,, pars medialis

Anterior commissure

Lateral posterior thalamic nucleus

Pul vinar

Ventral posterolateral thalamic nucleus

Medial geniculate body

Lateral posterior thalamic nucleus

Pul vinar

Ventral posterolateral thalamic nucleus

Medial geniculate body

Head of caudate nucleus

Ventral lateral thalamic nucleus

Red nucleus

Ventral lateral thalamic nucleus

Red nucleus

Lateral dorsal thalamic nucleus

Mediodorsal thalamic nucleus

Pulvinar

Centromedian thalamic nucleus

Lateral dorsal thalamic nucleus

Head of caudate nucleus

Anterior thalamic nucleus

Crus of fornix

Mediodorsal thalamic nucleus

Pulvinar

Centromedian thalamic nucleus

Crus of fornix

Lateral dorsal thalamic nucleus

Mediodorsal thalamic nucleus

Head of caudate nucleus

Pulvinar

Anterior thalamic nucleus

Centromedian thalamic nucleus

Anterior thalamic nucleus

Mediodorsal thalamic nucleus

Anterior commissure

Fornix

Anterior thalamic nucleus

Hypothalamus

Mammiliothaiamic tract

Mammillary body [hypothalamus)

Anterior thalamic nucleus

Mediodorsal thalamic nucleus

Anterior commissure

Fornix

Anterior thalamic nucleus

Hypothalamus

Mammiliothaiamic tract

Mammillary body [hypothalamus)

Crus of fornix

Lateral dorsal thalamic nucleus

Pulvinar

Centra median thalamic nucleus

Body of fornix

Thalamus

Interthalamic mass

Anterior commissure

Mammillary body _ (hypothalamus)

Body of fornix

Thalamus

Interthalamic mass

Anterior commissure

Mammillary body _ (hypothalamus)

Habenular commissure

Posterior commissure

W- Pinea! body

Great vein of Galen

Quadrigeminal plate or tectum of midbrain or colliculi or quadrigeminal tubercles

Cauda te-lent ¡cu lar gray bridges

Third ventricle

Hypothalamus

Anterior cerebral artery

Optic nerve

Claustrum

Nucleus accumbens

Body of caudate nucleus

Anterior limb of internal capsule

Putamen

Mucleus accumbens

Middle cerebral artery (M1)

Anterior cerebral artery [A1)

Internal carotid artery

Hypophysis (pituitary gland)

Hypophysis (pituitary gland)

Body of caudate nucleus

Anterior limb of internal capsule

Putamen

Mucleus accumbens

Middle cerebral artery (M1)

Anterior cerebral artery [A1)

Internal carotid artery

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