Ascends through the aortic hiatus in the diaphragm
Lies anterior to the bodies of T6-12 vertebral bodies, between the thoracic aorta and the azygos vein
Conveys lymph from the limbs, pelvic and abdominal cavities, left side of the thorax, left upper limb and left side of the head and neck
Empties into the venous system at the junction of the left internal jugular and left subclavian veins
i. Azygos venous system
Drains blood from the back and thoracoabdominal walls
Is highly variable
Is composed of an unpaired azygos vein and its main tributary, the hemiazygos vein.
Offers an alternate route for blood to reach the heart if the inferior vena cava is blocked
Azygos vein
arises from ascending lumbar and/or renal veins and subcostal veins
ascends on the right side of the bodies of T5-T12 vertebrae
arches over the root of the right lung to join the superior vena cava
receives blood from
hemiazygos vein
posterior intercostals veins
esophageal veins
bronchial veins
communications with the vertebral venous plexus
Hemiazygos vein
arises from the left subcostal and ascending lumbar veins
ascends on the left side of the vertebral column from T12-T9
crosses the T9 vertebrae posterior to the aorta, esophagus and thoracic duct to empty into the azygos vein
receives blood from
inferior three posterior intercostals
inferior esophageal veins
accessory hemiazygos (occasionally)
Accessory hemiazygos vein
begins at the 4th or 5th intercostal space on the left
descends on the left side of vertebrae T5-T8
crosses over T7 or T8 vertebrae to join the azygos
sometimes joins the hemiazygos
receives blood from
posterior intercostal veins from the 4th through 8th intercostal spaces
left superior intercostal vein (occasionally)
j. Vagus nerves and recurrent laryngeal nerves
The right vagus nerve
enters the thorax anterior to the right subclavian artery and immediately gives rise to the right recurrent laryngeal nerve, which
loops around the right subclavian artery and ascends into the neck
descends on the right side of the trachea
passes posterior to the right brachiocephalic vein, superior vena cava and root of the right lung
gives rise to branches of the right pulmonary plexus
continues to the esophagus, where it contributes to the esophageal nerve plexus and continues as the anterior vagal trunk
into the abdomen
The left vagus nerve
enters the mediastinum between the left common carotid and left subclavian arteries
descends with the left phrenic nerve to the aortic arch
gives off the left recurrent laryngeal nerve just below the arch, which loops around the arch and ascends into the neck
passes posterior to the root of the left lung where it contributes to the left pulmonary plexus
continues as a single nerve to the esophagus where it contributes to the esophageal nerve plexus and continues as the
posterior vagal trunk into the abdomen
k. Phrenic nerves
Supply motor and sensory fibers to the diaphragm
Enter the superior mediastinum between the subclavian artery and brachiocephalic vein on either side
Pass anterior to the roots of the lungs, unlike the vagus nerve
The right phrenic nerve descends on the right side of the inferior vena cava to the diaphragm
The left phrenic nerve
crosses the arch of the aorta
descends anterior to the root of the left lung and along the pericardium over the left atrium and ventricle
pierces the diaphragm to the left of the pericardium
- Thoracic sympathetic trunks
Are continuous with the cervical and lumbar sympathetic trunks
Shift medially as they descend, crossing from the heads of the ribs to the costovertebral joints to the sides of the vertebral bodies
Give off the paired thoracic splanchnic nerves
greater splanchnic: from T5-T9 vertebral levels
lesser splanchnic: from T10-T11 vertebral levels
least splanchnic: from T12 vertebral level
