Introduction: Advancing in neuroimaging and clinical studies have showed that the frontal lobe, previously known as a silent lobe in surgery, plays an important role in cognition, behaviour, learning and speech processing. Damage to the fiber tract in frontal lobe may result in more severe irreversible deficits. For this reason, the fiber tracts are an essential consideration in determining resection limits. We examined the ‘frontal aslant tract’ in frontal lobe, which is considered as involved in motor learning, initiation and fluency of speech, in MRI tractography and postmortem human brain specimens.

Methods: 10 formalin-fixed human brain were examined by fiber dissection technique. Our findings were supported with MRI tractography in healty volunteers. We examined the relationship of the frontal aslant tract with other fiber tracts and cortex in the frontal lobe. Our anatomical findings were also briefly compared with functional data from clinical-radiological analysis and intraoperative stimulation of fiber tracts.

Results: The frontal aslant tract extending from supplemantary motor area to pars opercularis in vertical plane is an association fiber tract. It is situated averaged 2.7± 0.5 cm deep from the premotor cortex, and between the superior longitudinal fasciculus II and corona radiata fibers. It is considered as involved in initiation and fluency of speech.

Conclusions: The frontal aslant tract should be take into account in frontal lobe surgery in order to avoid, in particular,postoperative speech deficits.

Patient Care: Frontal Aslant Track is a white matter pathway extended between supplementary motor area and Broca region. There are neurostimulation studies on Frontal Aslant Track which has a role on speech initiation and fluency. Especially in cases of glioma , for frontal region surgery, we believe having good knowledge of fiber anatomy and evaluating with preoperative imaging techniques will improve the surgical success. Also we believe supplementary motor area and Frontal Aslant Track fiber bundles should be protected in classical frontal lobectomy surgery.

Learning Objectives: To examine the microsurgical and radiological features of the frontal aslant tract for more accurate and safe surgery in frontal lesions.

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