The gray matter of the two halves of the thalamus is divided by a vertical sheet of white matter called the 23:42 The Brain and Cranial Nerves The gray matter of the two halves of the thalamus is divided by a vertical sheet of white matter called the A) intermediate mass B) internal capsule C) internal medullary lamina D) internal peduncle Answer: C Learn More : Share this Share on FacebookTweet on TwitterPlus on Google+