Bulb of occipital horn

The bulb of the occipital horn (a.k.a. the bulb of the corpus callosum), is a smooth prominence on the medial wall of the atrium and occipital horn of the lateral ventricle.

It is produced by the underlying forceps major, the fibres of the splenium of the corpus callosum that curve posteriorly into the occipital lobes. In the medial ventricular wall, the bulb lies superior to the calcar avis, which is produced by the inward impression of the calcarine sulcus. Figure 2 on page 3 of the referenced paper illustrates the bulb (OB), calcar avis (CA), and collateral trigone (T) in the atrium.

Key concept

Splenium → forceps major → bulb of the occipital horn, whereas calcarine sulcus → calcar avis.