Course relations and distribution of both vagii in thorax

The vagus nerves, also known as the tenth cranial nerves, are a pair of important nerves that play a crucial role in the autonomic nervous system. In the thorax, the vagus nerves course through and provide innervation to various structures. Here’s a description of the course, relations, and distribution of both vagus nerves in the thorax:

Course of Vagus Nerves in Thorax:

1. Origin:
   • The vagus nerves, right and left, originate from the medulla oblongata in the brainstem.
2. Passage Through Jugular Foramen:
   • After originating in the brainstem, the vagus nerves exit the skull through the jugular foramen.
3. Descend in the Neck:
   • The vagus nerves descend through the neck, running posterior to the carotid arteries.
4. Penetrate the Thoracic Cavity:
   • As the vagus nerves reach the superior mediastinum, they enter the thoracic cavity.
5. Course in the Thorax:
   • Within the thorax, each vagus nerve follows a somewhat parallel course on either side of the body.
6. Anterior to the Subclavian Artery:
   • The right vagus nerve descends anterior to the subclavian artery on the right side.
7. Posterior to the Subclavian Artery:
   • The left vagus nerve descends posterior to the arch of the aorta and the left subclavian artery.
8. Pulmonary Plexus:
   • As the vagus nerves continue downward, they contribute fibers to the pulmonary plexus, which is involved in the innervation of the lungs.
9. Esophageal Plexus:
   • The vagus nerves give off branches to form the esophageal plexus, providing innervation to the esophagus.
10. Cardiac Plexus:
    • Both vagus nerves contribute fibers to the cardiac plexus, which plays a role in regulating the heart rate.
11. Anterior to the Root of the Lung:
    • The right vagus nerve passes anterior to the root of the right lung, while the left vagus nerve passes anterior to the root of the left lung.
12. Anterior to the Esophagus:
    • Both vagus nerves continue downward, anterior to the esophagus.
13. Pierces the Diaphragm:
    • Each vagus nerve pierces the diaphragm and enters the abdominal cavity.

Relations in the Thorax:

• Right Vagus Nerve:
  • In the thorax, the right vagus nerve is closely related to the subclavian artery and the right brachiocephalic vein.
• Left Vagus Nerve:
  • In the thorax, the left vagus nerve is closely related to the arch of the aorta and the left subclavian artery.

Distribution:

1. Heart:
   • Both vagus nerves contribute to the cardiac plexus, regulating heart rate and cardiac function.
2. Lungs:
   • The pulmonary plexus, formed by the vagus nerves, provides innervation to the bronchial tree and blood vessels in the lungs.
3. Esophagus:
   • The esophageal plexus, formed by branches of the vagus nerves, innervates the esophagus.
4. Abdominal Organs:
   • In the abdominal cavity, the vagus nerves continue to innervate various organs, forming the anterior and posterior vagal trunks.

Understanding the course, relations, and distribution of the vagus nerves in the thorax is crucial for comprehending their functional roles in regulating autonomic functions, including cardiovascular and respiratory activities. Dysfunction or injury to the vagus nerves can lead to various clinical manifestations, emphasizing the importance of their anatomical knowledge in clinical practice.