= Right marginal branch
A \b[right marginal branch] is a branch of the <right coronary artery> running toward the right ventricular margin and contributing to supply of the <right ventricle>. More than one marginal artery can occur.<Anatomy and Physiology 2e by J. Gordon Betts and others>[Section 19.1, right-coronary marginal branches and Figure 19.15]{ref} The name concerns a branching route and territory rather than a separate main coronary origin from the <aorta>.
The distinction between parent flow and branch flow is quantitative. In an original steady model, let a proximal right-coronary segment supply a marginal branch plus all remaining represented branches. Then <conservation of mass> gives
$$
Q_{\rm right}=Q_{\rm marginal}+Q_{\rm remaining}.
$$
Chosen values $80=30+50\,\mathrm{mL\,min^{-1}}$ satisfy the balance. A measurement of the proximal $80$ would not establish that the marginal branch receives $80$.
Nor does the adjective marginal imply negligible importance. A branch's functional contribution depends on its supplied tissue and actual flow, while its name describes an anatomical location. <Coronary dominance> addresses the origin of the <posterior descending artery>, so it answers a different classification question from identifying a marginal branch.
An anatomical or angiographic observation should therefore specify the main vessel, the branch connection and the represented region. A visible route can guide the interpretation of a selective measurement, but branch patency, flow and <coronary oxygen delivery> remain distinct observables.
Back to article page
