At a summer party, one of your friends throws a water balloon at your head. Which motor pathway carries the stimulus that lets you reflexively move your head and neck so you don't get hit?

Tectospinal pathway

Explanation:

The tectospinal pathway is one of the indirect motor pathways and extends from any of the motor centers of the brainstem and extends into the spinal cord. The Tectospinal motor pathway sends the nerve impulses from superior colliculus to contralateral skeletal muscles which in turn cause reflex movement of head, eyes, and trunk. Here, the stimuli may be visual or auditory.

The superior colliculus obtains the visual input from the eyes (here, seeing a thrown balloon) and auditory input from the ears. These sudden stimuli trigger the superior colliculus to produces action potentials along the tectospinal tract. The arrival of neural signals from the tectospinal tract activates skeletal muscles in the head and trunk. These muscles reflexively move the head, eyes, and trunk.