Brain Diagram Labeled Reticular Formation

All 11 parts on the diagram

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From the side 8

Reticular formation A net of nuclei in the core of the brainstem. It runs from the lower medulla to the upper midbrain.
Midbrain The top part of the brainstem. The reticular formation reaches up to its upper end.
Pons The middle part of the brainstem, bulging forward. The reticular formation runs through it.
Medulla oblongata The lowest part of the brainstem. The reticular formation begins at its lower end.
Thalamus The mass above the midbrain. Some paths from the reticular formation relay here on the way to the cortex.
Projections to the cerebral cortex Paths from the reticular formation up to the cortex. They help keep the brain awake and alert.
Sensory input from the spinal cord Sensory paths from the spinal cord feed the net. One is called the spinoreticular tract.
Reticulospinal tracts Paths from the reticular formation down the spinal cord. They take part in posture and walking.

Cut across 3

Median column (raphe nuclei) The column on the midline, the raphe nuclei. Cells here make serotonin.
Medial column The column beside the midline. Its nuclei are called gigantocellular.
Lateral column The outer column. Its nuclei are called parvocellular.

How this list was compiled: Every name checked on 2026-10-01 in both of these. (1) Wikipedia, English edition, Reticular formation, https://en.wikipedia.org/wiki/Reticular_formation. (2) Kenhub, Reticular formation, https://www.kenhub.com/en/library/anatomy/reticular-formation. The name spinoreticular tract and the relay in the thalamus were checked in (1) and in (3) The University of Texas Medical School at Houston, Neuroscience Online, Pain Tracts and Sources, https://nba.uth.tmc.edu/neuroscience/m/s2/chapter07.html. Detail lines are in our own words. Licence: own work

The drawing: Drawn for this site on 2026-10-01 from plain geometry; nothing traced. Licence: own work

How it works

The reticular formation is a net of nuclei in the core of the brainstem. Here is the brain labeled, reticular formation first, from the side; a second drawing cuts across the brainstem to show its three columns.

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From the side

Ring 1 is the reticular formation, the net-patterned strip. It runs through rings 2 to 4, the midbrain, the pons and the medulla oblongata. Ring 5 is the thalamus, and the arrows of ring 6 fan out from it to the cerebral cortex. Ring 7 is the arrow in from the spinal cord and ring 8 the arrow back down it.

Cut across

The cut has the back of the brainstem at the top. Ring 9 is the median column, on the midline. Ring 10, with large dots, is the medial column and ring 11, with small dots, the lateral column. Both are drawn on each side.

Median means on the midline; medial means next to it. The raphe nuclei are the median column.

Questions and answers

Where is the reticular formation located?

In the core of the brainstem. It runs from the bottom of the medulla oblongata, through the pons, to the top of the midbrain, in between the more compact nuclei and tracts.

What does the reticular formation do?

Its paths up to the cerebral cortex help keep the brain awake and alert. Its paths down the spinal cord, the reticulospinal tracts, take part in the control of posture and walking.

What are the three columns of the reticular formation?

The median column on the midline, made of the raphe nuclei; the medial column beside it, which holds the gigantocellular nuclei; and the lateral column outside that, which holds the parvocellular nuclei. Each half of the brainstem has all three.

Why is it called the reticular formation?

Reticular comes from the Latin reticulum, a net. Its nerve cells and their fibers form a loose net with no sharp edge, unlike the compact nuclei around it.