MCQ – 73113

Correct Answer � C Explanation

Answer C. Fornix

• The fornix is the main efferent system of the hippocampus and an important part of the limbic system.

• It is one of the commissural fibers connecting the cerebral hemispheres.

Gross anatomy

• Roughly C-shaped, the fornix extends from the hippocampus to the mammillary bodies of the hypothalamus and the anterior nuclei of the thalamus.

• It is a curvilinear bundle of white matter fibers that begins as a group of myelinated fibers called the alveus.

• The alveus joins to form the fimbria of the hippocampus.

• The fimbria of each hippocampus thickens and then splits off from the hippocampus to form the crus (leg) of the fornix.

The fornix is composed of four parts:

• crura: best seen at the splenium of the corpus callosum at the level of the superior colliculus on coronal images

• commissure: connects the crura

• body: from the merging of the crura, provides one of two major paths through which the hippocampus communicate with each other

• columns (anterior pillars): curves anteriorly and dives into the hypothalamus (mammillary bodies)