What is the Taenia sagittalis?
Taenia sagittalis, or sagittal bundle, is the most prominent pectinate muscle in the Right atrium, so called because of its wormlike appearance.
What is pectinate muscles?
Pectinate muscles are muscular ridges in the atria arranged like the teeth of a comb and are more common on the right than on the left.
The pattern of Taenia sagittlais
Type 1 – Perpendicular to the crista terminalis (m/c, 40%~45% of cases)
Type 2 – Parallel to the crista terminalis (18%~20% of cases)
Type 3 – Combination of type 1 and 2 (11%~15% of cases)
Type 4 – Branching (9%~10%)
Type 5 – Interlacing trabeculations (9%~10%)
Type 6 – Prominent muscular columns (5%~8%)
The pectinate muscles develop in the primitive RA and are displaced laterally with the expansion of the RA.
They increase the surface area of the RA and allow for dilatation without wall stress.
Taenia sagittalis is usually of no clinical significance but could be the origin of atrial flutter or fibrillation.
Right atrial catheters may get stuck deep relative to prominent pectinate muscles or the taenia sagittalis, especially in complex anatomies
→ Need cardiac surgery to remove the catheter, if it is stuck between pectinate muscles
Reference)
RadioGraphics 2019 39:5, 1238-1263
