Limen insulae

Limen insulae

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Published in Terence R. Anthoney, Neuroanatomy and the Neurologic Exam, 2017

At the rostro-inferior angle of the roughly triangular insula, there is a break in the surrounding circular sulcus, where the insula is continuous with the temporal and frontal lobes. Authors of many recent textbooks in basic neuroanatomy label this area as the “limen insulae” (e.g., B&K, p. 217; C&S, p. 32; MarMar, p. 62, Heim, p. 73; N&F, p. 232 [Fig. 92]). Since “limen” is Latin for “threshold” or “entrance” (Simpson, 1963, p. 132), “limen insulae” may be translated as “threshold to the insula.”

Posttraumatic subgaleal herniation of an intracranial cerebral arterial segment

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Journal Information

Published in Baylor University Medical Center Proceedings, 2019

Manav Bhalla, John L. Ulmer, Andrew P. Klein, Kieran E. McAvoy, Namrata M. Bhalla

The MCA has four segments: M1 (sphenoidal: MCA origin to insular genu), M2 (insular: limen insulae to circular sulcus), M3 (opercular: circular sulcus to sylvian fissure surface), and M4 (cortical: sylvian surface to cortical branches over lateral hemisphere). Cortical branches may arise from superior, inferior, or intermediate trunks, are two to eight in number, and have a mean diameter of 0.44 to 2.47 mm.3 The diameters of M1, M2–M3, and cortical branches range from 2.5 to 4 mm, 1 to 2 mm, and 1 mm, respectively.4 Situated in the subarachnoid space, the cortical branches enter the brain by perforating the pia mater. The diagnostic utility of CTA relies on optimal image acquisition with respect to contrast bolus.5 The smallest arterial size detected on CTA and DSA is 0.7 and 0.4 mm, respectively.6 No normal caliber arteries in the subgaleal space are visible with current CTA resolution.

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Posttraumatic subgaleal herniation of an intracranial cerebral arterial segment