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Henry Gray (1825–1861).  Anatomy of the Human Body.  1918.
 
the cells of the thalamus form four principal groups or stalks: (a) those of the anterior stalk pass through the frontal part of the internal capsule to the frontal lobe; (b) the fibers of the posterior stalk (optic radiations) arise in the pulvinar and are conveyed through the occipital part of the internal capsule to the occipital lobe; (c) the fibers of the inferior stalk leave the under and medial surfaces of the thalamus, and pass beneath the lentiform nucleus to the temporal lobe and insula; (d) those of the parietal stalk pass from the lateral nucleus of the thalamus to the parietal lobe. Fibers also extend from the thalamus into the corpus striatum—those destined for the caudate nucleus leave the lateral surface, and those for the lentiform nucleus, the inferior surface of the thalamus.


FIG. 719– Hind- and mid-brains; postero-lateral view. (See enlarged image)

  The Metathalamus (Fig. 719) comprises the geniculate bodies, which are two in number—a medial and a lateral—on each side.
  The medial geniculate body (corpus geniculatum mediale; internal geniculate body; postgeniculatum) lies under cover of the pulvinar of the thalamus and on the lateral aspect of the corpora quadrigemina. Oval in shape, with its long axis directed forward and lateralward, it is lighter in color and smaller in size than the lateral. The inferior brachium from the inferior colliculus disappears under cover of it while from its lateral extremity a strand of fibers passes to join the optic tract. Entering it are many acoustic fibers from the lateral lemniscus. The medial geniculate bodies are connected with one another by the commissure of Gudden, which passes through the posterior part of the optic chiasma.
  The lateral geniculate body (corpus geniculatum laterale; external geniculate body; pregeniculatum) is an oval elevation on the lateral part of the posterior end of the thalamus, and is connected with the superior colliculus by the superior brachium. It is of a dark color, and presents a laminated arrangement consisting of alternate layers of gray and white substance. It receives numerous fibers from the optic tract, while other fibers of this tract pass over or through it into the pulvinar. Its cells are large and pigmented; their axons pass to the visual area in the occipital part of the cerebral cortex.

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