page_title: Interthalamic adhesion
hierarchical_section_title: Interthalamic adhesion
context_page_description: The interthalamic adhesion is a flattened band of tissue that connects both parts of the thalamus at their medial surfaces. The medial surfaces form the upper part of the lateral wall to the third ventricle.
  In humans it is only about one centimeter long, though in females it is larger by about 50%. Sometimes it is in two parts and 20% of the time it is absent. In other mammals it is larger.
  In 1889, a Portuguese anatomist by the name of Macedo examined 215 brains, showing that male humans are approximately twice as likely to lack an interthalamic adhesion as are female humans. He also reported its absence, still reported today at about 20 per cent. Its absence is seen to be of no consequence.
  The interthalamic adhesion contains nerve cells and nerve fibers; a few of the latter may cross the middle line, but most of them pass toward the middle line and then curve laterally on the same side. It is still uncertain whether the interthalamic adhesion contains fibers that cross the mid-line and for this reason it is inappropriate to call it a commissure.
  The interthalamic adhesion is notably enlarged in patients with the type II Arnold–Chiari malformation.
context_section_description: The interthalamic adhesion (also known as the intermediate mass or middle commissure) is a flattened band of tissue that connects both parts of the thalamus at their medial surfaces. The medial surfaces form the upper part of the lateral wall to the third ventricle.
  In humans it is only about one centimeter long, though in females it is larger by about 50%. Sometimes it is in two parts and 20% of the time it is absent. In other mammals it is larger.
  In 1889, a Portuguese anatomist by the name of Macedo examined 215 brains, showing that male humans are approximately twice as likely to lack an interthalamic adhesion as are female humans. He also reported its absence, still reported today at about 20 per cent. Its absence is seen to be of no consequence.
  The interthalamic adhesion contains nerve cells and nerve fibers; a few of the latter may cross the middle line, but most of them pass toward the middle line and then curve laterally on the same side. It is still uncertain whether the interthalamic adhesion contains fibers that cross the mid-line and for this reason it is inappropriate to call it a commissure.
  The interthalamic adhesion is notably enlarged in patients with the type II Arnold–Chiari malformation.
caption: Dissection showing the ventricles of the brain. (Interthalamic adhesion labeled as Massa Intermedia at center right.)
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