ISSN 0016-5840 - Gegenbaurs morphol. Jahrb.· Leipzig- 133 (1987) 1, S. 175-184 From the Institute of Anatomy, Faculty of Medicine, Beograd (Yugoslavia) (Head: t». D. Mrvaljevic) Size and Position of the Human Adhaesio interthalamica By Siobodan Malobabic, Laslo Puskas and Milena Blagotic With 4 Figures Received April 1, 1986 Abstract In 50 human brains, we investigated the size of the ad haesio inter thalamica, length of CA-CP line, position of the centre of adhaesio interthalamica, and the distance between the corpus cal- losum and adhaesio interthalamica. Interthalamic adhesion was absent in 11 brains (22 %) and was duplicated in 1 brain. In all 50 brains, length of the intercommissuralline (CA-CP) had a mean value of 2,56 em, in brains with the interthalamic adhesion 2,48 ern, and 2,56 cm in brains without it. t-test for this difference showed no significant result for a probability of 0,05 (t = 1,95). Midsagittal section area of ad haesio interthalamica had a mean value of 13,1 mrn? (min = 1,5 mrn": max = 34 mm-). There is no correlation between the length of CA-CP line and the size of the midsagittal section area of ad haesio interthalamica (the correlation coefficient was 0,06). The centre of ad- haesio intert.halarnica was most often situated above the CA-CP line and around the perpendicular line through its middle portion. The distance between the corpus callosum and intert.halarnio ad- hesion, measured in standardized system of CA-CP line, had a mean value 1,4 cm (min = 0,7 crn , ma,x = 2,3 cm). OUt" results eonf'irm the opinions that the presence or size of the intert.halarnic adhaesion depends not directly on the size of the correspond ing brain (diencephalon). Introduction Adhaesio interthalamica [PNA; massa inter media (BNA); commissura rnollis] , well developed in mammals, contains several nuclei. In man it is smaller, contains only the nucleus reuniens and a part of nucleus rhomboideus (CARPENTER1976, PEELE 1977, l=tABI1958), and in about 20% of cases it is even absent. Human ad- haesio interthalamica except decussating, contains commissural fiber systems con- necting some thalamic nuclei (ZAWISCH1952). The significance and eventual mani- festations of its presence or absence is not known in humans. Knowledge of the mor- phology, size, and position of interthalamic adhaesion is important in neurosurgery as well as in neuroradiology and neuroanatomy. It is especially important becuse of its great variability in the human brain.