Arterial Baroreceptor Fibers from the Aortic Region of the Dog in the Cervical Vagus Nerve

The neural pathways followed by sensory fibers from arterial baroreceptors in the aortic region of the dog were investigated with neurophysiological recording. Systemic arterial baroreceptor fibers separate from the depressor nerve were found in the left cervical vagus in each of five dogs investigated; at most two fibers were isolated from each dog due to the difficulty of the dissection. These fibers originated from or above the aortic arch region. One baroreceptor fiber had its arterial sensory ending below the fifth rib. In the right cervical vagus in six dogs, visual evidence of fiber activity from systemic arterial baroreceptors could not be produced; only subjective (auditory) evidence for the presence of systemic arterial baroreceptor fibers was obtained. The number of these arterial baroreceptor fibers, which run in the vagus nerve but are not part of the depressor nerve, appeared to be smaller than the number of arterial baroreceptor fibers in the depressor nerve.