Illustrated Encyclopedia of Human Anatomic Variation: Opus III: Nervous System: Brain: Fissures and Sulci
Ronald A. Bergman, PhD
Adel K. Afifi, MD, MS
Ryosuke Miyauchi, MD
Peer Review Status: Internally Peer Reviewed
Triradiate termination of the sylvian fissure has been reported.
According to Cunningham, the anterior rami of the sylvian fissure may assume different configurations: they may be Y-shaped where the two rami, enclosing the triangular frontal gyrus, join the sylvian fissure by a common stem (32% of hemispheres); the two rami may join the sylvian fissure separately, and they may be V- or U-shaped (37% of hemispheres); or a single ramus may join the fissure (30% of hemispheres). Less frequently, there are more than two rami, or the two rami are reduced to one (taking the position of either one of them) or are intermediate in position.
In one study, two rami were observed in 85% of Brains, one ramus in 12%, and three rami in 3%.
The length of the anterior ascending ramus varies from 10 to 30 mm, and of the anterior horizontal, from 10 to 25mm.
The sylvian fissure is frequently longer on the left hemisphere than on the right.
References
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Connolly, C.J. (1941) The fissural pattern in the brain of Negroes and Whites. The frontal lobe. Am. J. Physiol. Anthrop. 28:133-165.
Connolly, C.J. (1942) The fissural pattern in the brain of Negroes and Whites. The parietal and temporal lobes. Am. J. Physiol. Anthrop. 29:225-265.
Cunningham, D.J. (1890) The fissure of Rolando. J. Anat. Physiol. 25:1-23.
Debierre, C. (1891) Sur les anomalies des circonvolutions du cervéau de l'homme. Duplicilé de la sissure de Rolando, absence de la scissure de Rolando. Soc. Biol. Comptes Rendus Hebdomadaires des Séances et Mémoires. 43:369-372.
Gerlach, E.J. and H. Weber. (1929) über ein menschliches Gehirn mit beiderseitger Verdoppelung der Zentralfurche. Anat. Anz. 67:440-452.
Leggiardi-Laura, C. (1901) Sur la signification de la "duplicité de la scissure de Rolando" et sur un rapport constant de la scissure post-rolandique. Arch. Ital. Biol. 36:355.
Linell, E.A. and B.M. Koster. (1924) A developmental anomaly of the cerebral cortex. Arch. Neurol. Psychiatry 12:167-172.
Sergi, S. (1911) Variations de developpement du lobe frontal chez l'homme. Arch. Ital. Biol. 55:138-139.
Sperino, G. (1901) Decrizione morfologica dell'encefalo del Prof. Carlo Giacomini. Int. Monatsschrift. Anatomie and Physiology 18:313-386.
Thompson, R.B. (1911-12) Complete unilateral interruption of the fissure of Rolando. J. Anat. Physiol. 45:433-437.
Tricomi, G. (1902) Deux cas de duplicité du sulcus Rolandi. Arch. Ital. Biol. 37:490.
Waterson, D. (1907) Complete bilateral interruption of the fissure of Rolando. J. Anat. Physiol. 41:143-146.
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