Interthalamic adhesion | |
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Details | |
Part of | Thalamus |
Identifiers | |
Latin | adhaesio interthalamica |
NeuroNames | 301 |
NeuroLex ID | nlx_144100 |
TA98 | A14.1.08.103 |
TA2 | 5778 |
FMA | 74869 |
Anatomical terms of neuroanatomy |
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 about 50% larger on average. [1] Sometimes, it is in two parts – and 20% of the time, it is absent. [2] 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 in about 20% of humans. Its absence is seen to be of no consequence. [2]
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 midline – 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. [3]
The thalamus is a large mass of gray matter on the lateral walls of the third ventricle forming the dorsal part of the diencephalon. Nerve fibers project out of the thalamus to the cerebral cortex in all directions, known as the thalamocortical radiations, allowing hub-like exchanges of information. It has several functions, such as the relaying of sensory and motor signals to the cerebral cortex and the regulation of consciousness, sleep, and alertness.
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This article describes anatomical terminology that is used to describe the central and peripheral nervous systems - including the brain, brainstem, spinal cord, and nerves.
This article incorporates text in the public domain from the 20th edition of Gray's Anatomy (1918)