A new segment of the trochlear nerve: cadaveric study with application to skull base surgery.
Objectives The trochlear nerve is important to preserve during approaches to the skull base. Traditionally, this nerve has been divided into cisternal, cavernous, and orbital segments. However, the authors anecdotally observed an additional segment during routine cadaveric dissections. Therefore, they performed this study to better elucidate this anatomy. Design Twenty latex-injected cadaveric sides (10 adult cadavers) were dissected with the aid of an operating microscope. Standard microdissection techniques were used to examine the course of the distal cisternal and precavernous segments of the trochlear nerve. Setting Cadaver laboratory. Main Outcome Measures Measurements were made using a microcaliper. Digital images were made of the dissections. Results The authors identified a previously undescribed segment of the trochlear nerve in all specimens. This part of the nerve coursed between the entrance of the trochlear nerve into the posterior corner of the oculomotor trigone to the posterior wall of the cavernous sinus. This segment of trochlear nerve was, on average, 4 mm in length. Conclusions The authors have identified a new segment of the trochlear nerve not previously described. They propose that this be referred to as the trigonal segment. Knowledge of the microanatomy of the trochlear nerve is useful to skull base surgeons.
Department of Pediatric Neurosurgery, Children's Hospital, University of Alabama, Birmingham, Alabama, United States ; Department of Anatomical Sciences, School of Medicine, St. George's University, Grenada.
R Shane
RS
Tubbs
Department of Anatomical Sciences, School of Medicine, St. George's University, Grenada.
Philip
P
Veith
Department of Pediatric Neurosurgery, Children's Hospital, University of Alabama, Birmingham, Alabama, United States.
Christoph J
CJ
Griessenauer
Department of Anatomical Sciences, School of Medicine, St. George's University, Grenada.
Marios
M
Loukas
Goodman Campbell Brain and Spine, Department of Neurological Surgery, Indiana University School of Medicine, Indianapolis, Indiana, United States.
Aaron A
AA
Cohen-Gadol
cranial nerves; microanatomy; neurosurgery; trochlear nerve