Sinuatrial nodal artery (heart, anatomy)

The sinuatrial nodal artery may arise as a branch of one or both of two larger arteries:

• the right coronary artery:
  • present in 55% of the population
  • originates proximally in the course of the right coronary artery just after it has emerged from the right coronary sinus
• the circumflex branch of the left coronary artery:
  • present in 45% of the population
  • originates just after the circumflex artery has diverged from the left coronary artery
  • passes superiorly and to the right, posterior to the aorta and superior to the upper, left pulmonary vein

Often, the artery forms an arterial ring around the structures it supplies:

• right atrium
• right auricle
• sinuatrial node

Rarely, the sinuatrial artery may arise directly from the right coronary sinus separately from the right coronary artery.