Direct Laryngoscopy · Tip-to-Wrist Lever
The laryngoscope is a rigid L. The lift load lives at the blade tip; your wrist has to resist its torque. The closer your hand sits to the vertex, the shorter the tip-to-wrist radius and the more your forearm lines up with the blade.
The laryngoscope is a rigid L: the blade runs from the vertex into the airway, the handle runs up from the same vertex. The lift load lives at the blade tip — roughly 38 N at the clinical peak. Your wrist has to hold the torque that load makes about the wrist joint, and that torque is the tip force times the tip-to-wrist radius.
Grip right at the base (the vertex) and your hand sits as close to the tip as the geometry allows: the radius is just the blade length, and your forearm lines up with the blade so the pull runs straight back to the shoulder. Slide your hand up the handle and that radius stretches into the long diagonal across the L — same tip load, bigger lever, more wrist torque.
Length isn't the whole story. At the base the tip sits on the forearm's line, so the load is an almost pure axial pull — the wrist's strong direction. Up the handle, the grip is offset from that line; the load now twists the wrist in its weak plane, which both adds to the lever and shaves the wrist's effective torque capacity.
Push the force slider toward the peak with the grip mid-handle and the budget gauge blows past 100%. That's the regime where people stop lifting and start levering on the teeth instead — the exact failure the geometry predicts.
This lines up with the "hold close to the blade" teaching: closest to the blade is the base/vertex, which is precisely where the lever and the off-axis offset are both smallest.