The road branches from the Arras-Sangatte road near Therouanne capital of the Morini Tarouanna civitas Morinorum (celt. root tarvos "bull" + suffix enna or anna). Other early forms are Tarvenna in the Antonine Itinerary and Tervanna in the Peutinger Table).

Therouanne was a major junction with other roads leading off to Cassel (Castellum Menapiorum) and to Hesdin in the valley of the Canche. The Boulogne branch leaves the Arras road at a typical fork about one kilometre north of Therouanne. Names are listed from Therouanne to Boulogne.

summary
1 Clety Celti|acum, Gallo Roman personal name Celtus with acum
2 Ouve-Wirquin
3 Ouve
4 Drioville
5 le Mesnil-Boutry
6 Senlecques Sanilius|acum, lat. masculine name with ger. phonetic development of acum
7 Les Coutteaux
8 Wirwignes
9 Bertenlaire
10 Baincthun Old English, Bag|ingas|tun, farm of Bago's followers
11 Mont Lambert
12 Brequerecque suffix acum with Germanic phonetic development
13 Boulogne Bononia celt. "low place" as opposed to Gesoriacum gal. gaesum "spear" with acum "place", the citadel on its rocky spur