The tegmentum (from Latin for "covering) is a general area within the brainstem. It is located between the ventricular system and distinctive basal or ventral structures at each level. It forms the floor of the midbrain.
It is a multisynaptic network of neurons that is involved in many unconscious homeostatic and reflexive pathways.
the tegmentum is the anterior half of the neural tube
. However, for fetuses
to adults, tegmentum only refers to the parts of the brain that remains relatively unchanged after development is complete, i.e. at the brain stem
. Other parts, on the other hand, develop further, through folding and thickening, and have different names. Still, it is considered a continuous central region through all levels of the brainstem.
Structures that develop to grow ventral or lateral outside this primitive tube as add-ons (e.g. the crus cerebri in the anterior of the midbrain) are not considered part of the 'tegmentum' as they are not part of the primitive neural tube but grow as projections from the cerebral cortex. Whereas, parts that were inside the primitive neural tube and remained an integral part of it after complete development (e.g. the red nucleus) are considered part of the tegmentum.
The tegmentum forms distinguished divisions in the midbrain
The midbrain tegmentum
is the part of the midbrain
extending from the substantia nigra
to the cerebral aqueduct
in a horizontal section of the midbrain.
Lateral tegmental field
The lateral tegmental field (LTF) is the source of several neurons of the noradrenaline system
of the brain
Other pertinent areas of the tegmentum are: