Anatomy of the Vessels and Nerves of the Trunk (Angioneurology) - Chornokulskyi S. T. 2011

Autonomic (Vegetative) Nervous System
Peripheral Division of the Autonomic Nervous System
Efferent Pathways of the Autonomic (Vegetative) Nervous System

Efferent autonomic pathways, as noted above, vary in complexity depending on the level at which they synapse into the efferent limb of the reflex arc. The most complex efferent autonomic pathway originates in the Cerebral Cortex.

The Cell bodies of the first (efferent) Neurons are located in the cortex of the frontal, temporal, and parietal lobes. The axons of these neurons reach the supraoptic and paraventricular nuclei, as well as the nuclei of the infundibulum and mammillary bodies (the cell bodies of the second neurons). This segment of the pathway is referred to as the frontotemporal-parieto-hypothalamic fibers (fibrae fronto-temporo-parieto-hypothalamicae).

The axons of these second neurons converge, forming the dorsal longitudinal fasciculus, or Schütz's bundle, at the border of the Midbrain and Diencephalon. This bundle descends through the Brainstem, synapsing on neurons across all autonomic nuclei of cranial nerve pairs III, VII, IX, and X.

The fibers of the dorsal longitudinal fasciculus continue into the Spinal Cord, where they lie anterior to the lateral corticospinal tract and synapse on neurons of the lateral intermediate substance at C₈—L₂, as well as the sacral parasympathetic nuclei S2—S4*.

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Fig. 64. Diagram of the parasympathetic innervation of Organs and Tissues:

1 — ciliary ganglion;

2 — postganglionic parasympathetic (secretory) fibers to the submandibular and sublingual Salivary Glands;

3 — submandibular ganglion;

4 — postganglionic parasympathetic (secretory) fibers to the lacrimal gland;

5 — pterygopalatine ganglion;

6 — postganglionic parasympathetic (secretory) fibers to the nasal mucosa;

7 — postganglionic parasympathetic (secretory) fibers to the parotid gland.

8 — otic ganglion;

9 — Branches of the Vagus nerve to thoracic organs;

10 — intramural ganglia in the walls of abdominal viscera;

11 — intramural ganglia in the walls of abdominal viscera;

12 — preganglionic parasympathetic fibers within the vagus nerve supplying the viscera;

13 — vagus nerve;

14 — accessory (parasympathetic) Nucleus (Edinger-Westphal nucleus);

15 — superior salivatory and lacrimal nuclei;

16 — inferior salivatory nucleus;

17 — posterior (dorsal) parasympathetic Nucleus of the vagus nerve;

18 — sacral parasympathetic nuclei;

19 — preganglionic parasympathetic fibers within the pelvic splanchnic nerves;

20, 21 — intramural ganglia of the pelvic organs (third-order)

The indicated brainstem and spinal cord neurons serve as the cell bodies of third-order neurons that give rise to nerves and white rami communicantes (preganglionic fibers of the efferent peripheral pathway). Preganglionic fibers travel to autonomic ganglia, which house the cell bodies of fourth-order (effector) neurons. The axons of these fourth-order neurons reach the target organs.

* It is believed that this portion of the bundle axons down to S2-S4 separates into the subependymal fasciculus and courses anterior to the central canal.