Pars orbitalis
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View Callum Smith's current disclosuresAt the time the article was last revised Craig Hacking had no recorded disclosures.
View Craig Hacking's current disclosures- Brodmann's area 47/12
The pars orbitalis refers to the most rostral portion of the inferior frontal gyrus in the frontal lobe of the brain. It is one of three parts that make up the inferior frontal gyrus along with the pars triangularis and pars opercularis 4-6. It plays a role in the language processing network of the brain.
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Gross anatomy
Relations
The pars orbitalis lies ventral to the anterior horizontal ramus (a.k.a. anterior ramus) of the lateral sulcus (a.k.a. Sylvian fissure). It extends along the ventral most part of the lateral surface of the frontal lobe as far as the caudal segment of the lateral orbital sulcus 4-6.
Blood supply
It is supplied by the frontal branches of the middle cerebral artery.
Radiographic features
Radiographically the pars orbitalis can be identified as the most rostral portion of the inferior frontal gyrus which takes on a characteristic “M” configuration. This is also referred to as the M sign when identifying the inferior frontal gyrus 3.
Function
Although the pars orbitalis is not defined by cytoarchitecture, it is closely affiliated to Brodmann’s areas 47/12 1. Traditionally not considered to be a core language area, new studies suggest in the dominant hemisphere it plays a more significant role in language processing with its involvement in semantic processing, phonological processing and syntax 1. The function of the same cortical region in the non-dominant hemisphere is not as well documented but has been shown to be involved in behavioural and motor inhibition and deductive reasoning 2.
References
- 1. De Carli D, Garreffa G, Colonnese C, Giulietti G, Labruna L, Briselli E, Ken S, Macrì MA, Maraviglia B. Identification of activated regions during a language task. Magnetic resonance imaging. 25 (6): 933-8. doi:10.1016/j.mri.2007.03.031 - Pubmed
- 2. Wildgruber D, Riecker A, Hertrich I, Erb M, Grodd W, Ethofer T, Ackermann H. Identification of emotional intonation evaluated by fMRI. NeuroImage. 24 (4): 1233-41. doi:10.1016/j.neuroimage.2004.10.034 - Pubmed
- 3. M. Wagner, A. Jurcoane, E. Hattingen. The U Sign: Tenth Landmark to the Central Region on Brain Surface Reformatted MR Imaging. American Journal of Neuroradiology. 34 (2): 323. doi:10.3174/ajnr.A3205 - Pubmed
- 4. Michael Petrides. Neuroanatomy of Language Regions of the Human Brain.(2014) ISBN: 9780124059313
- 5. Juergen K. Mai, George Paxinos. The Human Nervous System.(2012) ISBN: 9780080921303
- 6. Stephan Ulmer, Olav Jansen. fMRI. ISBN: 9783642343421
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