| Objective: The purpose of this study was to describe the features about the shape, location and the adjacent relationships of the ?membranous portion of interventricular septum (abbreviated as MPIS) in adult hearts. It is very important in cardiac surgical interventions, Interventional radiology and iconographical diagnosis. Methods: This study was based on macroscopic combining the heart as an ex-situ-organ and sectional anatomy. The shape , position and adjacent sturectures of the MPIS were investigated macroscopically on 64 embalmed human hearts as an ex-si tu-organ. The features of the MPIS in-situ-dissection were observed in thoracic section . Results: 1. The shape: In these 64 cases the following shapes of the MPIS were found: irregular, 16(25.00%); triangular, 14(21. 88%) ; semi lunar, 11 (17. 91%); circular, 10(15.63%); oval, 7(10.94%); quadrangular, 3(4.68%); wedge-shaped, 3(4.68%). 2. The position and the attachment: (l)The left side of the MPIS located betweenthe adjacent part of anterior and right posterior aortic cusps and the muscular septal crest . It participates in the formation of the anteromedial wall of the outflow tract of left ventricular. In 24 cases (37.50%) the superior border of the MPIS was in direct continuity with the intercups triangle between the anterior and the right posterior aortic cusps, 19 (29. 69%)only with the right posterior aortic cusp, 4 (6. 25%)'only with the anterior aortic cusp; In 17(26.56%) the superior border of the MPIS was below the attached portion of both cusps. The inferior border of the MPIS was attached to the muscular septal crest. (2) The right side of MPIS was on the anterior point of the atrioventricular septum and the site of the anteromedial commessure. 3. Subdivisions: The septal cusp of the tricuspid valve attachment to MPIS. The line of the attachment divides the MPIS into two portions, in 42cases , 65.62%. The upper one separates the left outflow tract from the cavity of the right atrium, called the atrioventricular portion of the MPIS, the lower one separates the outflow tract of left ventricle and the right ventricle , called interventriclar porttion of MPIS. The latter is thiner and more translucent and is normally partly concealed by septal cusp of the tricuspid valve. 16 cases (25.00%) wereobserved absence of atrioventricular portion , only interventricular portion, because the right side of MPIS located totally under the line. While 6(9.38%) cases were observed only having atrioventricular portion but not interventriclar portion, because the right side of MPIS located totally above the line . 4. The orientation and The angulation: MIPS takes up the posterior 1/3 part of the interventricular septum on the thoracic transverse section through the oval fossa. On the coronary section through aorta, the MIPS lies obliquely and extends upwards and right from muscular septum to the aortic fibrous annulus to which the posterior aortic cusp is attached. The MPIS is orientated at an angle of about 45?to median plane, but the angulation varies according to the obliquity of the aortic root. Conclusion: The shape of MPIS vary. The position and adjacent relationships of the MPIS on the left side and the right side are difference. The shape, position and adjacent relationships of the MPIS could be demonstrated clearly in the transverse sections and coronary sections on the thorax. To understand and appreciate the shape, position, adjacent relationships of MPIS and its features in-situ-dissection can provide some guidance for cardiac surgical interventions and iconographical diagnosis.
|
PDF Full Text Request