Sympathetic division and the emergency response

Usage was not settled in 1915. Bayliss insisted that the autonomic system includes the sympathetic.⁵ He noted that some writers abroad used the name for all the visceral nervous system other than the sympathetic, and he called this practice confusing and unjustified by the facts.⁵ He still granted that the sympathetic has peculiarities not shared by the rest of the autonomic system, which he promised to describe in a later chapter.⁵ He wanted one name for the whole visceral system, set against the somatic system.⁵ Sherrington (1906) had written of the sympathetic system with Langley's term "autonomic" in brackets beside it, treating the two names together.¹

In The Integrative Action of the Nervous System (1906), Sherrington wrote that the afferent nerve-fibres in the sympathetic system, as judged by their number in the white rami, are comparatively few. He cited recent observations by Warrington as conclusive.¹ He also pointed to trunks. In the nervous system serving the outer environment, wholly afferent trunks are common. In the sympathetic system none was known, while wholly efferent trunks exist, such as the cervical sympathetic trunk.¹ He read this as a sign of poor afferent paths from the interoceptive field.¹ Bayliss's bibliography lists de Boer (1913), who stated that striated muscles receive their tonic innervation through connecting branches of the sympathetic.⁶

Cannon's Bodily Changes in Pain, Hunger, Fear and Rage (1915) set out the link between nerve and gland. The adrenal gland lies in front of each kidney and has a cortex and a medulla. From the medulla can be extracted a substance called suprarenin, adrenin, epinephrine or adrenalin, which in very small amounts affects structures innervated by the sympathetic division.² Cannon placed rage and intense excitement in the activity of this division. He listed pupil dilation, inhibited digestion, pallor and a faster heart as typical results.³ He added that the sympathetic neurones can readily overwhelm conditions set by the cranial division, as shown by their dominance over digestion.⁴ Crile's 1926 bibliography lists Cannon's 1914 paper on the emergency function of the adrenal medulla in pain and the major emotions.⁷

The autonomic system appears in recent work as a domain that can be brought under control. Fields and Levin (2022) described yoga and biofeedback as ways for a system to forge new links between higher and lower levels. They compared gaining control over formerly autonomic functions to finding new axes in physiological spaces for which the higher-level self had no actuators.⁸ They said such processes depend on interoception.⁸