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The four names identify distinct pathways: chorda tympani, the sensory buccal nerve, the radial nerve formerly called musculospiral, and the obturator nerve. Origin must include the parent nerve or nerve plexus, while the function must follow the actual fibre supply rather than the name of a structure crossed.

Chorda tympani. This branch leaves the facial nerve in its descending facial canal before the stylomastoid foramen. It enters the tympanic cavity from behind, passes forwards between the malleus and incus close to the inner surface of the tympanic membrane, and leaves through the petrotympanic fissure. In the infratemporal fossa it joins the lingual nerve, a branch of the mandibular division of the trigeminal nerve. It then travels with that carrier towards the tongue and submandibular ganglion.

The chorda tympani carries taste from the anterior two thirds of the tongue, with sensory cell bodies in the geniculate ganglion and central connections to the nucleus of the solitary tract. It also carries preganglionic parasympathetic fibres from the superior salivatory nucleus towards the submandibular ganglion; postganglionic fibres supply the submandibular gland and sublingual gland. It does not provide the general touch supply of that part of the tongue; that travels through the lingual nerve's trigeminal nerve pathway. Taste and tactile testing can consequently distinguish two functions that briefly share one peripheral trunk.^[ref]

Buccal nerve. In the usual anatomical meaning intended by this list, this is the long buccal nerve from the anterior division of the mandibular trigeminal nerve. It commonly emerges between the heads of the lateral pterygoid muscle, descends near the anterior border of the mandibular ramus and the temporalis muscle insertion, and passes towards the cheek. Its branches reach cheek skin, the buccal mucosa, and the buccal gingiva beside the lower molars. It is principally sensory. The motor supply of the buccinator muscle comes from the facial nerve, whose buccal branches are a different set of nerves. Thus the ability to hold the cheek against the teeth and sensation in the cheek are not tests of the same efferent pathway.^[ref]

Radial nerve, historically musculospiral. This is the major continuation of the posterior cord of the brachial plexus, usually containing fibres from C5–T1. It passes from the axilla into the posterior arm, accompanying the profunda brachii artery in the radial groove of the humerus. It pierces the lateral intermuscular septum and reaches the anterior compartment between brachialis and brachioradialis. Near the lateral elbow it divides into a superficial sensory branch and a deep motor branch. The latter passes through the supinator muscle and continues as the posterior interosseous nerve.

The radial nerve supplies triceps brachii and anconeus, then brachioradialis, the radial wrist extensors and, through its deep continuation, the principal finger and thumb extensors and associated posterior forearm muscles. Its sensory branches supply posterior arm and forearm regions and part of the dorsolateral hand. A lesion's level matters: an arm lesion can impair wrist and finger extension, while an isolated superficial branch lesion is sensory and does not itself cause a wrist drop. Conversely, a posterior interosseous nerve lesion chiefly affects motor function. The fingertip pads are not the characteristic autonomous sensory territory of the superficial radial nerve.^[ref]

Obturator nerve. It arises from the anterior divisions of the anterior rami of L2–L4 in the lumbar plexus. It emerges from the medial border of psoas major, crosses the pelvic side wall and leaves through the obturator canal with the obturator vessels. Its anterior and posterior divisions characteristically run on opposite sides of adductor brevis, although the level of division varies. The anterior division supplies adductor longus, gracilis and commonly adductor brevis; the posterior division supplies obturator externus and the adductor portion of adductor magnus, with variable additional contributions. The hamstring portion of adductor magnus has a different supply. Cutaneous supply to a variable medial-thigh patch and articular branches to the hip and knee supplement its principal motor role in thigh adduction. Obturator internus is supplied by its own sacral-plexus nerve, not by the obturator nerve merely because the names resemble one another.^[ref][ref]

The two pneumogastric nerves are the right and left vagus nerves, the tenth cranial nerves: mixed sensory, branchial motor and parasympathetic pathways from the medulla oblongata to the neck, thorax and abdomen. A useful description separates their apparent origin at the surface of the brain from the origins and terminations of their component fibres.

Rootlets emerge in the groove behind the inferior olive, between the glossopharyngeal nerve above and the accessory rootlets below. Branchial motor fibres arise chiefly in the nucleus ambiguus; preganglionic parasympathetic fibres arise in the dorsal motor nucleus of the vagus and, particularly for cardiac control, the nucleus ambiguus. Visceral sensory fibres have their cell bodies chiefly in the inferior vagal ganglion and terminate centrally in the nucleus of the solitary tract; somatic sensory fibres associated with the superior vagal ganglion project to the spinal trigeminal nucleus. Consequently a sensory fibre is not accurately described as originating in a motor nucleus simply because its peripheral nerve emerges nearby.^[ref]

Each vagus nerve leaves the skull through the jugular foramen, with the glossopharyngeal nerve and accessory nerve. It bears the small superior vagal ganglion at the foramen and the larger inferior vagal ganglion below it. Connections include communications with adjacent cranial nerves and the cervical sympathetic nervous system. Traditional descriptions assign fibres joining the vagus nerve from the cranial part of the accessory nerve to the latter peripheral nerve; their modern classification is more nuanced and does not change the peripheral branches being described. In the neck the vagus nerve descends in the carotid sheath, behind and between the internal jugular vein and the internal, then common, carotid artery.

Its meningeal and auricular branches supply small sensory territories of the cranial covering and external ear. Pharyngeal branches contribute to the pharyngeal plexus, supplying much of the soft palate and pharynx; the stylopharyngeus muscle belongs to the glossopharyngeal nerve and the tensor veli palatini muscle to the mandibular division of the trigeminal nerve. The internal branch of the superior laryngeal nerve supplies sensation above the vocal folds; its external branch supplies the cricothyroid muscle. The recurrent laryngeal nerve supplies the other intrinsic laryngeal muscles and sensation below the vocal folds. The right recurrent laryngeal nerve loops beneath the right subclavian artery; the left loops under the aortic arch beside the ligamentum arteriosum. Both return towards the larynx near the groove between trachea and oesophagus.^[ref]

In the thorax, both vagus nerves pass behind the roots of the lungs, contrasting with the anterior course of the phrenic nerves. Cardiac branches join the cardiac plexus; pulmonary branches join the pulmonary plexus. The trunks break up into the oesophageal plexus, then collect principally as an anterior trunk derived from the left vagus nerve and a posterior trunk derived from the right. Through the oesophageal hiatus they reach the stomach; hepatic and coeliac branches distribute to abdominal viscera. Their parasympathetic territory includes foregut and midgut derivatives, extending into the proximal colon, rather than every abdominal and pelvic organ.^[ref] This extensive distribution explains why the level of experimental section is indispensable information.

The main consequences of section can be organized by the interrupted functions:

A discriminating historical experiment would record respiratory movements and heart rate before and after section, distinguish unilateral from bilateral section, and compare an intact airway with an airway bypass. A tracheal cannula can separate obstruction at the glottis from changes in the respiratory rhythm, while the central-versus-peripheral stimulation comparison separates incoming reflex traffic from outgoing motor effects. Later separate-lung recordings confirmed that a change following unilateral section could affect both lungs, supporting a central reflex interpretation rather than simple local paralysis.^[ref] The gastric distinction is also borne out by measurements of persistent acidity after surgical vagotomy, despite major reductions in stimulated gastric acid secretion.^[ref]