The headwaters of the Rein da Medel flow through the Val Cadlimo, a small west–east valley south of the main Alpine ridge in the municipality of
Quinto in the canton of Ticino. This is officially Italian-speaking territory; the Italian name of the creek is . There are three almost equally strong source streams: • The southern spring trickle flows through the
Lago Scuro ( and thereafter becomes a creek, between
Punta Negra and
Bassa del Lago Scuro (a pass). • The central spring trickle rises on the
Bocchetta di Cadlimo (a pass at ) and shortly thereafter flows through the
Lago di Dentro (). • The northern spring trickles rise beneath the
Pizzo Curnera (). The northern spring trickles are about 640 meters long. The southern and western spring creeks are about 1,000 meters from their start to the confluence before the ''Lago dell'Isra'' (). . About four kilometers to the east after the Lago dell'Isra at the end of its first valley, the Val Cadlimo, the Reno di Medel forms a steep little
gorge that virtually "crosses" the
Gotthard Base Tunnel about above it and marks the transition from the Val Cadlimo to the
Val Medel. Just below, the gorge opens out, a tributary flows in from the south which comes down from the Passo dell'Uomo via the Val Termine. In this area, the Reno di Medel form the boundary between the municipalities of
Quinto and
Blenio. A few meters north of the inflow into the
Lai da Sontga Maria reservoir (), the boundary between Ticino and Graubünden is a straight line between
Lukmanier Pass and Pizzo Scai, which ignores the local topography. Now in the Grisons, the creek flows through the
Sursilvan speaking part of the canton. The middle section of the river is called
Froda; the lower section is called
Rein da Medel. The name change takes place at the confluence of major tributary
Rein da Cristallina down from south-east. The middle and lower sections of the river flows through the Val Medel it created. Most of this section belongs to the municipality of
Medel, except the uppermost bit lies in Ticino and the last kilometer belongs to the municipality of
Disentis/Muster. Numerous small tributaries flow into the Reno di Medel throughout the entire Val Medel. The last two kilometers, just north and below the village
Curaglia () and after the confluence with the
Rein da Plattas (which come from a south-east valley of the same name), lead through a canyon named
Las Ruinas (), where the Reno di Medel flows into the
Anterior Rhine at about above
sea level, just east below the road bridge across the Anterior Rhine on the road to the Lukmanier Pass. == Flow lengths ==