0 a Latin word meaning "three-sided," used in medical names and descriptions: --
the os trigonum
Fibers enter the trigonum habenul from the stalk of the pineal gland, and the habenular commissure.
It is continuous behind with a flattened triangular area, the trigonum collaterale, situated between the posterior and inferior cornua.
The trigonum habenul also contains groups of nerve cells termed the ganglion habenul.
Exceptionally, the lateral of these tubercles forms an independent bone called "os trigonum" or accessory talus.
They are often situated at the level of the trigonum.
