Position and size of massa intermedia in Serbian brains

Massa intermedia, a midline bar-shaped structure, connects two thalami across the third ventricle in 70-80% of healthy humans. It has become clinically important since its absence was comprehended as a midline malformation of the brain and brought in connection with schizophrenia indicating that some symptoms could be a consequence of disturbed neuron chains underlying the mechanisms of attention and processing of information. The aim of the investigation was to find out the incidence, position, and size of massa intermedia in the brains of the Serbian population.

Our investigation was performed on 41 brains of adult Serbian cadavers using a macro dissection method.

Massa intermedia was present in 80.49% of cases, in 1 case it was double. In most of the cases it was located in the superior quadrants of the lateral wall of the third ventricle, the larger part being in the anterosuperior one. Some other combinations were also present. The horizontal diameter of the cross-section was larger than vertical and was not in correlation with the length of the third ventricle. The average cross-sectional area was 29.58 mm2, significantly larger in females.

Massa intermedia is present in most of the investigated brains, usually connecting the anterior-superior quadrants of the lateral walls of the third ventricle. Different in shape and size its cross-section is a horizontal ellipse, significantly larger in females. The cross-sectional area and the size of the third ventricle are not in correlation.