Resumen de Morphological and biometric characteristics of the pectinate muscles and the taenia sagittalis of the right atrium in the human heart

Ana Barriga, Jorge Henriquez, Enrique Olave

• The crista terminalis (CT) is a well-defined fibro-muscular crest formed by the union of the venous sinus and the primitive right auricle, which extends along the posterolateral face of the right atrial wall. The pectinate muscles (PM) are muscular crests which extend anterolaterally from the CT to the auricle and may present in a series of variable shapes and sizes. The biggest and most promi-nent PM is called the taenia sagittalis (TS). PM with highly trabeculated muscle fibres predispose patients to the occurrence of arrhythmias. The pre-sent article is a descriptive study of the anatomical and biometric characteristics of the right atrium. We studied 30 hearts of adult Chilean individuals, aged between 18 and 84 years, of both sexes, with no apparent cardiac pathology, belonging to the Normal Human Anatomy Unit of the Basic Scienc-es Department of Universidad de La Frontera. The samples were washed with distilled water and im-mediately placed in formalin at 10%. The atria were first separated from the ventricles, then opened perpendicularly through the intercaval zone to give access to the interior. The distribution of pectinate muscles found, according to the clas-sification of Loukas et al. (2008) and Siddiqui et al. (2013), was as follows: Type I, 20%; Type II, 23.3%; Type III, 23.3%; Type IV, 6.7%; Type V, 6.7%; Type VI, 20%. TS was found to be presentin 46.6% of the hearts examined, two or more TS in 29.8% and no TS in 23.6%. The length of the pectinate muscles is variable; the shortest are lo-cated on the medial wall. Six types of pectinate muscle patterns were observed.