BRS

Chapter 13 Diencephalon: Thalamus and Hypothalamus

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Anterior limb

Caudate nucleus

Genu

Globus pallidus

Corticobulbar fibers

Putamen

Posterior limb

Corticospinal fibers

Thalamus

Auditory radiation (sublenticular part of internal capsule) to superior temporal gyrus (areas 41 and 42)

Sensory radiations from VP nucleus to areas 3, 1, 2

Medial geniculate body (audition)

Lateral geniculate body (vision)

Visual radiation (retrolenticular portion of internal capsule) to striate cortex of occipital lobe (area 17)

FIGURE 13.3. Horizontal section of the right internal capsule showing the major fiber projections. Lesions of the internal capsule result in contralateral hemiparesis and contralateral hemianopia. VP, ventral posterior. (Modified with permission from Fix JD. High-Yield Neuroanatomy . 3rd ed. Lippincott Williams & Wilkins; 2005:118.)

C. Posterior limb ■ located between the thalamus and the lentiform nucleus. ■ contains the sensory radiations (pain, temperature, and touch). ■ contains the corticospinal fibers. ■ includes the retrolenticular (visual) and sublenticular (auditory) radiations.

VI. BLOOD SUPPLY OF THE INTERNAL CAPSULE (See Figure 3.6)

A. Anterior limb ■ irrigated by the medial striate branches of the anterior cerebral artery and by the lateral striate branches (lenticulostriate) of the middle cerebral artery. B. Genu ■ perfused either by direct branches from the internal carotid artery or by pallidal branches of the anterior choroidal artery. C. Posterior limb ■ supplied by branches of the anterior choroidal artery and lenticulostriate branches of the mid dle cerebral arteries.

VII. CLINICAL CONSIDERATIONS

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A. Infarction of the internal capsule ■ most frequently results from occlusion of the lenticulostriate branches of the middle cerebral artery and results in the following contralateral conditions: