Lungs and Ventilation Pathway - LO 6

6. Review the autonomic innervation of the thoracic viscera.

Thoracic viscera are affected by sympathetic and parasympathetic innervation. In general, all thoracic viscera derive sympathetic innervation from T1-T5/6 spinal cord levels, while parasympathetic innervation is derived from the vagus n. (CN X).

There are three main autonomic plexuses associated with thoracic viscera: cardiac, pulmonary, and esophageal. All plexuses are continuous.

Cardiac plexus: there are two parts of the cardiac plexus: superficial (located inferior to arch of aorta and sandwiched between arch and pulmonary trunk) & deep (located between arch of aorta and tracheal bifurcation).

• • Sympathetic function: dilate coronary arteries and accelerates heart rate

  • Parasympathetic function: constrict coronary arteries and slows heart rate

Pulmonary plexus: located anterior and posterior to the root of the lungs; continuous with cardiac plexus (easily observable at tracheal bifurcation) and esophageal plexus

• • Sympathetic function: bronchodilation and constriction of pulmonary vasculature

  • Parasympathetic function: maintenance of tone or bronchoconstriction of smooth muscle of bronchi and dilation of pulmonary vasculature

Esophageal plexus: surrounding the inferior 2/3rds of the esophagus (inferior to root of lungs)

• • Sympathetic function: vasoconstriction of esophageal vasculature

  • Parasympathetic function: peristalsis of smooth muscle

  • The superior 1/3rd of the esophagus is composed of skeletal muscle and is innervated by the recurrent laryngeal n. and sympathetic fibers