Anatomy - Posterior Mediastinum Flashcards
Boundaries of posterior mediastinum?
- Superiorly: sternal angle2. Inferiorly: diaphragm3. Laterally: mediastinal pleura4. Anteriorly: pericardial sac
6 major structures of the posterior mediastinum?
- Esophagus with its plexus (right and left)2. Thoracic aorta with its branches3. Azygos system of veins4. Thoracic duct and associated lymph nodes5. Sympathetic trunks6. Thoracic splanchnic nerves
Vertebral borders of esophagus?
C6 to T11
What is the esophagus?
Muscular tube
Pathway of esophagus in posterior mediastinum?
Anterior aspect of vertebrae in midline => anterior and to the left to be anterior to the thoracic aorta to enter the diaphragm
Vertebral level of esophagus passing through esophageal hiatus to enter diaphragm?
T10
Esophagus 2 attachments?
- Pharynx2. Diaphragm
What is the right side of the esophagus covered by?
Mediastinal pleura
Position of thoracic duct in regards to esophagus in posterior mediastinum?
- Inferior portion: right side - Superior portion: left side
Position of aorta in regards to esophagus in posterior mediastinum?
Left
Position of right pulmonary artery and left main bronchus in regards to esophagus in posterior mediastinum?
Anterior
4 structures that are posterior to the esophagus at some point in the posterior mediastinum?
- Thoracic duct2. Hemiazygos veins3. Right posterior intercostal vessels4. Thoracic aorta (near diaphragm)
At what 4 locations can the esophagus be compresses/narrowed? What is at higher risk at these locations?
- Junction of esophagus and pharynx in the neck2. Aortic arch crossing over the esophagus in superior mediastinum3. Left main bronchus crossing over the esophagus in posterior mediastinum4. At esophageal hiatus in posterior mediastinum Higher risk of swallowed objects getting lodged at these locations and if the object is corrosive it would cause more damage at these locations
What arteries do esophageal arteries arise from?
- Thoracic aorta2. Bronchial arteries3. Ascending branches of left gastric artery in abdomen 4. Inferior thyroid artery
What veins do esophageal veins drain into?
- Azygos vein2. Hemiazygos vein3. Left gastric vein in abdomen
Lymphatic drainage of esophagus in posterior mediastinum?
- Posterior mediastinal lymph nodes2. Left gastric lymph nodes (inferior 1/3rd)
Innervation of esophagus?
Branches from vagus nerves and sympathetic trunks
Innervation of striated muscle in superior portion of the esophagus?
Branchial efferents from vagus nerves
Innervation of smooth muscle fibers in inferior portion of the esophagus?
Preganglionic fibers that are parasympathetic visceral efferents and synapse in the myenteric and submucosal plexuses of the enteric NS in the esophageal wall
Sensory innervation of esophagus? Which ones are responsible for transmitting pain information to the CNS?
Visceral afferents in :1. Vagus nerves2. Sympathetic trunks3. Splanchnic nerves
Are the visceral afferents from the vagus nerves involved in the relay of pain recognition?
NOPE
What are the 2 trunks formed by the esophageal plexus?
Trunks formed by the esophageal plexus just above the diaphragm:1. Anterior vagal trunk on anterior surface of esophagus mainly from fibers from left vagus nerve2. Posterior vagal trunk on posterior surface of esophagus mainly from fibers from right vagus nerveThese continue through the diaphragm
To which lymph nodes does esophageal cancer spread?
- Lymph nodes in neck2. Lymph nodes around celiac artery
Technique to assess site of esophageal cancer?
Endoscopy or barium swallow
Survival rate of esophageal rupture caught early? Untreated?
Caught early: 65%Untreated: 0%
Where do esophageal ruptures occur typically? Treatment?
Lower third of esophagus on the left Treatment: urgent surgical repair
Consequences of esophageal rupture?
- Sudden rise in intraluminal esophageal pressure produced by vomiting2. Uncoordination and failure of cricopharyngeus muscle to relax3. Large left pleural effusion that contains the gastric contents 4. Subcutaneous emphysema (air gets into tissues under the skin)
Which lung is in contact with the esophagus?
Right lung
Vertebral levels of thoracic aorta?
T4 to T12
Pathway of thoracic aorta?
Left of midline => approaches midline and directly anterior to vertebrae inferiorly => aortic hiatus through diaphragm
7 branches of the thoracic aorta?
- Pericardial2. Bronchial3. Esophageal4. Mediastinal5. Posterior intercostal6. Superior phrenic7. Subcostal
What is the azygos system of veins?
Series of longitudinal vessels on each side of the body that drain blood from the body wall and move it superiorly to drain into SVC (but blood from viscera may also enter them)
Where are anastomoses found with the azygos system of veins?
With abdominal veins
Are the azygos veins connected from side to side?
YUP
What happens if the IVC is blocked?
Azygos system of veins will serve as an anastomotic pathway capable of returning blood from lower part of body to the heart
3 major veins of azygos system of veins?
- Azygos vein on right2. Hemiazygos vein on left3. Accessory hemiazygos vein on left
Pathway of azygos vein?
Arises in abdomen opposite L1 or L2 at junction between right ascending lumbar vein and right subcostal vein OR from IVC => aortic hiatus => posterior mediastinum to the right of the thoracic duct => arches anteriorly at T4 over root of right lung and right vagus nerve to drain into IVC before it enters pericardial sac
8 tributaries to azygos vein?
- Right superior intercostal vein2. 5th to 11th right posterior intercostal veins 3. Hemiazygos vein4. Accessory hemiazygos vein5. Esophageal veins6. Mediastinal veins7. Pericardial veins8. Right bronchial veins
What is the superior intercostal vein formed by?
Junction of 2nd, 3rd, and 4th intercostal veins
Other name for hemiazygos vein?
Inferior hemiazygos vein