Inferior frontal gyrus, pars triangularis

Eloquence

• Speech areas of the dominant hemisphere (usually left) are classed as eloquent by Spetzler-Martin and Sawaya; the template cannot show which hemisphere is dominant in an individual. (Spetzler and Martin 1986; Sawaya et al. 1998)

What it does

• In the dominant hemisphere (usually left), the pars triangularis and pars opercularis form Broca's region, which is involved in speech production. (Amunts et al. 1999; Knecht 2000)
• Corresponds approximately to Brodmann area 45; the extent of the cytoarchitectonic area varies markedly between individuals. (Amunts et al. 1999)

Arterial supply

• Supplied by cortical branches of the middle cerebral artery. (Tatu et al. 1998; Rhoton 2002)

Venous drainage

• Drained by superficial cortical veins, largely toward the superficial sylvian veins. (Rhoton 2002)

Deficits if injured

• Lesions of Broca's region in the dominant hemisphere (usually left) are associated with impaired speech production; the location of essential language sites varies widely between individuals. (Ojemann et al. 1989; Amunts et al. 1999)

Surgical relevance

• Because language sites vary between individuals, resections near the inferior frontal gyrus of the dominant hemisphere (usually left) are commonly guided by awake stimulation mapping. (Ojemann et al. 1989; Sanai et al. 2008)

On the template

Desikan-Killiany. Values describe the fsaverage template, not an individual or a population norm.

Area: pial surface of the fsaverage average, which is smoother than individual cortex. Volume: voxel count of the fsaverage aseg segmentation at 1 mm isotropic.

References

1. Spetzler RF, Martin NA. A proposed grading system for arteriovenous malformations. Journal of Neurosurgery 1986;65(4):476-483. doi:10.3171/jns.1986.65.4.0476
2. Sawaya R, Hammoud M, Schoppa D, Hess KR, Wu SZ, Shi WM, et al.. Neurosurgical Outcomes in a Modern Series of 400 Craniotomies for Treatment of Parenchymal Tumors. Neurosurgery 1998;42(5):1044-1055. doi:10.1097/00006123-199805000-00054
3. Amunts K, Schleicher A, B�rgel U, Mohlberg H, Uylings HBM, Zilles K. Broca's region revisited: Cytoarchitecture and intersubject variability. The Journal of Comparative Neurology 1999;412(2):319-341. doi:10.1002/(SICI)1096-9861(19990920)412:2<319::AID-CNE10>3.0.CO;2-7
4. Knecht S. Handedness and hemispheric language dominance in healthy humans. Brain 2000;123(12):2512-2518. doi:10.1093/brain/123.12.2512
5. Tatu L, Moulin T, Bogousslavsky J, Duvernoy H. Arterial territories of the human brain. Neurology 1998;50(6):1699-1708. doi:10.1212/WNL.50.6.1699
6. Rhoton AL. The Supratentorial Arteries. Neurosurgery 2002;51(suppl_4):S1-53-S1-120. doi:10.1097/00006123-200210001-00003
7. Rhoton AL. The Cerebral Veins. Neurosurgery 2002;51(suppl_4):S1-159-S1-205. doi:10.1097/00006123-200210001-00005
8. Ojemann G, Ojemann J, Lettich E, Berger M. Cortical language localization in left, dominant hemisphere. Journal of Neurosurgery 1989;71(3):316-326. doi:10.3171/jns.1989.71.3.0316
9. Sanai N, Mirzadeh Z, Berger MS. Functional Outcome after Language Mapping for Glioma Resection. New England Journal of Medicine 2008;358(1):18-27. doi:10.1056/NEJMoa067819