Comstock–Needham system

Vein terminology

Longitudinal veins

The Comstock and Needham system attributes different names to the veins on an insect's wing. From the anterior (leading) edge of the wing towards the posterior (rear), the major longitudinal veins are named:

• costa C, meaning rib
• subcosta Sc, meaning below the rib
• radius R, in analogy with a bone in the forearm, the radius
• media M, meaning middle
• cubitus Cu, meaning elbow
• anal veins A, in reference to its posterior location

Apart from the costal and the anal veins, each vein can be branched, in which case the branches are numbered from anterior to posterior. For example, the two branches of the subcostal vein will be called Sc₁ and Sc₂.

The radius typically branches once near the base, producing anteriorly the R₁ and posteriorly the radial sector Rs. The radial sector may fork twice.

The media may also fork twice, therefore having four branches reaching the wing margin.

According to the Comstock–Needham system, the cubitus forks once, producing the cubital veins Cu₁ and Cu₂. According to some other authorities, Cu₁ may fork again, producing the Cu_1a and Cu_1b.

As there are several anal veins, they are called A1, A2, and so on. They are usually unforked.

Crossveins

Crossveins link the longitudinal veins, and are named accordingly (for example, the medio-cubital crossvein is termed m-cu). Some crossveins have their own name, like the humeral crossvein h and the sectoral crossvein s.