THE NEUROVASCULAR RELATIONSHIPS AND THE BLOOD-SUPPLY OF THE TROCHLEARNERVE - SURGICAL ANATOMY OF ITS CISTERNAL SEGMENT

WE EXAMINED IN detail the cisternal segments of 15 trochlear nerves in brain stems injected with India ink and fixed in formalin. The nerves were found to emerge as singular trunks (33.3%), singular trunks with accessory rootlets (13.3%), or two or three roots with (26.7%) or wit hout accessory rootlets (26.7%). The nerves were in close relationship or in contact with the superior cerebellar artery, that is, with the main trunk of the superior cerebellar artery, its medial and lateral t erminal stems, the accessory superior cerebellar artery, and the vermi an, paravermian, collicular, and lateral hemispheric arteries as well as their small branches. Some of these vessels were connected by anast omoses in 86.7% of the cases. The anastomotic channels varied from 40 to 530 Ecm in diameter. The cisternal segment of each trochlear nerve was usually supplied by a single long artery, which most often arose f rom the vermian artery (26.7%) or the collicular artery (26.7%). The f eeding vessel ranged from 30 to 80 mu m in caliber. We discuss the pos sible clinical significance of the anatomic data observed in the prese nt study.