Branche interventriculaire antérieure
[...] Elle fournit : [...]
des artères diagonales destinées à la face antérieure du ventricule gauche, qui sont au nombre de DEUX À QUATRE. La première est souvent la plus volumineuse et peut naître au niveau de la terminaison du tronc de la coronaire gauche qui est alors trifurquée, dans cette configuration, elle est parfois appelée branche diagonomarginale, ANGULAIRE ou bissectrice..
https://quizlet.com/286485044/5-vascularisation-du-coeur-vas...

DIAGONAL BRANCHES of the left anterior descending coronary artery supply blood flow to the anterior and anterolateral walls of the left ventricle. There are usually denoted as D1, D2, D3, etc.
There are termed "diagonal" due to them branching from their parent vessel at acute angles. They extend over the left ventricle in a diagonal fashion toward the acute margin and the cardiac apex. They often run parallel to one another and are variable in number (OFTEN 2 TO 9). If a ramus intermedius artery is present, the DIAGONAL ARTERIES are less prominent and arise more distally. The first diagonal (D1) branch tends to be the most prominent. When the first diagonal is large, the other diagonal vessels tend to be small and run a shorter course.
https://radiopaedia.org/articles/diagonal-branches-of-the-le...



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Note added at 19 hrs (2021-12-19 13:26:01 GMT)
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Note the "If a RAMUS INTERMEDIUS artery is present ...", suggesting that the RI is not itself a diagonal artery as defined.