Ten Triangles around Cavernous Sinus for Surgical Approach, Described by Schematic Diagram and Three Dimensional Models with the Sectioned Images

Abstract

For the surgical approach to lesions around the cavernous sinus (CS), triangular spaces around CS have been devised. However, educational materials for learning the triangles were insufficient. The purpose of this study is to present educational materials about the triangles, consisting of a schematic diagram and 3-dimensional (3D) models with sectioned images. To achieve the purposes, other studies were analyzed to establish new definitions and names of the triangular spaces. Learning materials including schematic diagrams and 3D models with cadaver's sectioned images were manufactured. Our new definition was attested by observing the sectioned images and 3D models. The triangles and the four representative surgical approaches were stereoscopically indicated on the 3D models. All materials of this study were put into Portable Document Format file and were distributed freely at our homepage (anatomy.dongguk.ac.kr/triangles). By using our schematic diagram and the 3D models with sectioned images, ten triangles and the related structures could be understood and observed accurately. We expect that our data will contribute to anatomy education, surgery training, and radiologic understanding of the triangles and related structures.

Keywords: Cavernous Sinus; Cross Sectional Anatomy; Internal Carotid Artery; Microsurgery; Neuroanatomy; Three-dimensional Imaging.

Fig. 1

Schematic diagram and three dimensional (3D) models of reorganized triangles around the cavernous sinus (superior view of right side). In a schematic diagram, ten triangles are easily comprehended (A) and, in the 3D models, each structure related to the triangles is shown accurately (B). 1 = superoposterior triangle; 2 = superior triangle; 3 = middle triangle; 4 = inferior triangle; 5 = anteromedial triangle; 6 = anterolateral triangle; 7 = posterolateral triangle; 8 = posteromedial triangle; 9 = lateral triangle; 10 = medial triangle; II = optic nerve; III = oculomotor nerve; IV = abducens nerve; V1 = ophthalmic nerve; V2 = maxillary nerve; V3 = mandibular nerve; VI = abducens nerve; TG = trigeminal ganglion.

Fig. 2

Three dimensional models (A) embedding the coronal sectioned images of each triangle. At coronal +30 mm, the superior triangle (2) is located between the optic (II) and oculomotor (III) nerves (B). At coronal +14 mm, the superoposterior (1), superior, middle (3), and inferior (4) triangles can be identified with the optic, oculomotor, trochlear (IV), and ophthalmic (V1) nerves (C). At coronal +10 mm, the anteromedial (5) and anterolateral (6) triangles are found between the ophthalmic, maxillary (V2), and mandibular (V3) nerves, while posterior (Post.) clinoid process which is the vertex of the superoposterior triangle is visible (D). At coronal +4 mm, the medial triangle (10) is located between the dural entries of trochlear and abducens (VI) nerves, while the inferior and medial triangles are observed around the dural entry of trochlear nerve (E). At coronal 0 mm, the posterolateral (7) and lateral (9) triangles are partly observed (F). At coronal -6 mm, the posteromedial triangle (8) is identified between the apex of petrous part of temporal bone and the greater petrosal nerve (G). When setting the positions of the images, the anterior and posterior commissures were regarded as the reference points (25). The 1 = superoposterior triangle; 2 = superior triangle; 3 = middle triangle; 4 = inferior triangle; 5 = anteromedial triangle; 6 = anterolateral triangle; 7 = posterolateral triangle; 8 = posteromedial triangle; 9 = lateral triangle; 10 = medial triangle; II = optic nerve; III = oculomotor nerve; IV = abducens nerve; V1 = ophthalmic nerve; V2 = maxillary nerve; V3 = mandibular nerve; TG = trigeminal ganglion.

Fig. 3

In the PDF file, windows showing each 3D model and bookmarks of clinical trials. Images from left column are derived from references: B (22), D (18), F (20), and H (21). In the model tree, bookmark, and surface models windows of the PDF file, user can select 3D models of each structure, sectioned images, and clinical trial (A). Regarding clinical approaches, textbook figures (B, D, F, H) and correspondence with 3D models of this study (C, E, G, I) are shown. Interhemispheric approach through the superoposterior and superior triangles (B, C), pterional approach through the middle, inferior, anteromedial, and anterolateral triangles (D, E), middle cranial fossa approach through the posterolateral and posteromedial triangles (F, G), and retromastoid suboccipital approach through the lateral and medial triangles (E) can be operated virtually.

Fig. 4

The relationship of each triangle and each part of the internal carotid artery at lateral view of the right side for clinical approaches. On schematic drawing, each part of the internal carotid artery can be identified through the triangles except lateral and medial triangles of the posterior group (A). On the three dimensional models, interhemispheric approach, pterional approach, middle cranial fossa approach, and retromastoid suboccipital approach are demonstrated to access the internal carotid artery (B). 1 = superoposterior triangle; 2 = superior triangle; 3 = middle triangle; 4 = inferior triangle; 5 = anteromedial triangle; 6 = anterolateral triangle; 7 = posterolateral triangle; 8 = posteromedial triangle; 9 = lateral triangle; 10 = medial triangle; II = optic nerve; III = oculomotor nerve; IV = abducens nerve; V1 = ophthalmic nerve; V2 = maxillary nerve; V3 = mandibular nerve; VI = abducens nerve; VII = facial nerve; TG = trigeminal ganglion.