Spiral arms are parts of galaxies - both the galaxies and their spiral arms are huge, by our everyday standards. Spiral arms basically contain most of what the galaxies contain - including stars, dust, gas.
Look in the discussion for answers. Choose one!
The spiral arms
In spiral arms of spiral galaxies
A spiral galaxy or barred spiral.
Spiral arms come in different "flavors": 10% grand-design (two well-defined spiral arms) 60% multiple-arm, 30% flocculent spirals (no well-defined arms at all). Spiral arms seem to be trailing arms, but this is very hard to determine. In some rare cases, spiral arms may lead.
An ordinary spiral galaxy has spiral arms coming out of the core. In a barred galaxy, the central area consists of a bar of stars and the spiral arms are attached to the ends of the bar.
within or on the edges of the spiral arms.
It has no spiral arms.
Arms of spiral galaxies.
Our galaxy, the Milky Way, is a spiral galaxy (actually a bared spiral) and new stars are being born in the spiral arms.
arms
Arms
Stars form in the great clouds of gas and dust in the spiral arms of a galaxy.