Complex sentence: To achieve clear vision, signals from the semicircular canals are sent as directly as possible to the eye muscles: the connection involves only three neurons, and is correspondingly called the "three neuron arc".
Split into simpler sentences: To achieve clear vision, signals from the semicircular canals are sent as directly as possible to the eye muscles. For instance, the connection involves only three neurons, and is correspondingly called "Three-neuron-arc".