cannula
- n a small flexible tube inserted into a body cavity for draining off fluid or introducing medication
- Before the skull emerges, he 'collapses' it by inserting a three-millimeter instrument known as a cannula and extracting its fluid.
- The bur holes permit passage of a leucotome, or lobotomy cannula, a hollow needle through which a loop of wire can be slipped.
- But to make sure that his cannula is on target, he conducts a simple test.