Anatomy and pathology of the sinus node

The aim of this study is to review the key features of anatomy of the sinus node of the human sinus node and its pathological variations as reported in the literature and supplemented with our observations. The sinus node is located adjacent to important structures such as the right phrenic nerve and the nodal artery. Although intimately related to its matrix of fibrous tissue, the nodal cells are in contact with atrial myocardium through nodal extensions. Nodal cell numbers decrease with age as part of the normal aging process. Pathological changes include diminished size of node and nodal cell replacement with fibro-fatty tissues. The location of the normal sinus node is well recognised. There is variation in the relationship of the node and its arterial supply to the terminal crest and the cavo-atrial junction.