Superior & Posterior Mediastinum Flashcards
What are the contents of the Superior Mediastinum?
- Esophagus
- Trachea
- Aortic arch (and branches)
- Superior Vena Cava (and branches)
- Thymus gland
- Thoracic Duct
What are the contents of the Posterior Mediastinum?
- Esophagus
- Azygos Vein
- Thoracic Duct
- Thoracic Aorta
Which two veins compose the Brachiocephalic Veins?
- Internal Jugular Vein
- Subclavian Vein
Where are the Brachiocephalic Veins located?
Posterior to sternoclavicular joints
Where is the Superior Vena Cava located?
Inferior border of the 1st Right Costal Cartilage
What is the purpose of the Azygos Vein?
- Connects the Superior and Inferior Vena Cava
- Drains the posterior thorax and abdomen
Where is the Azygos Vein located?
- Right side of T5-T12
- Arches over root of Lung to join Superior Vena Cava
Where does the Azygos Vein receive blood from?
- Posterior Intercostals/Subcostals
- Vertebral Venous Plexus
- Mediastinal Vein
- Esophageal Vein
- Bronchial Veins
What is the purpose of the Hemiazygos Vein?
Junction of the Left Subcostal and Ascending Lumbar Veins
Which Intercostal Veins drain into the Hemiazygos Vein before going into the Azygos Vein system?
Left Intercostal Veins 9-12
Where is the Hemiazygos Vein located?
Left side of T9-12
Where does the Hemiazygos Vein receive blood from?
- Inferior posterior intercostal veins
- Inferior mediastinal vein
- Esophageal vein
Where is the Accessory Hemiazygos Vein located?
Left side of T5-T8
Where does the Accessory Hemiazygos Vein receive blood from?
- Middle posterior intercostal veins
- Left bronchial veins
- Left superior intercostal vein
Where does the Aortic Arch begin?
Posterior to the 2nd Right Sternocostal Joint (at the sternal angle)
What are the three usual branches of the Aortic Arch?
- Brachiocephalic Trunk
- Left Common Carotid
- Left Subclavian
What percent of the population has an Aortic Arch variation where the Left Common Carotid is a part of the Brachiocephalic Trunk?
27%
What percent of the population has an Aortic Arch variation where the Left Vertebral Artery is present?
5%
What percent of the population has an Aortic Arch variation where the patient has two Brachiocephalic Trunks?
1.2%
What percent of the population has normal Aortic Arch branches with no variation?
About 65%
What is an Aortic Coarctation?
A congenital stenosis of part of the Aorta
What is a Preductal Aortic Coarctation?
A stenosis in the Aorta proximal to the Ductus Arteriosus
-Occurs in infancy
What is a Postductal Aortic Coarctation?
A stenosis in the Aorta distal to the Ductus Arteriosus
-Occurs in adults
What are the classic signs of an Aortic Coarctation?
- Rib notching
- Classic 3 sign
Where is the descending Aorta located?
- Posterior to root of left lung, pericardium, esophagus
- Along the bodies of T5-T12
Where does the descending Aorta end?
Anterior to the inferior border of T12
What structures pass through the Aortic hiatus?
- Aorta
- Azygos Vein
- Thoracic Duct
What is the motor function of the Phrenic Nerve?
Controls Diaphragm
What is the sensory function of the Phrenic Nerve?
Sensation to:
- Diaphragm
- Pericardium
- Mediastinal pleura
At what level does the Right Phrenic Nerve enter the Diaphragm?
At T8 (through the Vena Cava Hiatus)
What nerve roots does the Phrenic Nerve arise from?
- C3
- C4
- C5
Where does the Right Vagus Nerve pass through in the Superior Mediastinum?
Between the Right Subclavian Artery and Right Brachiocephalic Vein
Where does the Right Recurrent Laryngeal Nerve loop around in the Superior Mediastinum?
- Posteriorly around Right Subclavian Artery
- Goes between Trachea and Esophagus to the Larynx
Where does the Left Recurrent Laryngeal Nerve loop around in the Superior Mediastinum?
Posteriorly around Aortic Arch lateral to Ligamentum Arteriosum
Where does Right Vagus Nerve pass through in the Posterior Mediastinum?
Posterior to the Esophagus (Posterior Vagal Trunk)
-Joins Esophageal Plexus
Where does Left Vagus Nerve pass through in the Posterior Mediastinum?
Anterior to the Esophagus (Anterior Vagal Trunk)
-Joins Esophageal Plexus
What nerve roots does the Greater Splanchnic Nerve arise from?
T5-T9
What nerve roots does the Lesser Splanchnic Nerve arise from?
- T10
- T11
What nerve roots does the Least Splanchnic Nerve arise from?
T12
Where do the presynaptic fibers of the Abdominopelvic splanchnic nerve go?
They pass behind the Diaphragm and synapse in the prevertebral ganglia in the abdomen
What is the function of the Thymus?
Production and maturation of T-cells
Where is the Thymus located?
- In the Superior-Anterior Mediastinum
- Posterior to the Manubrium
When is the Thymus the largest and most active?
During neonatal and pre-adolescent periods
-Atrophies and replaced by fat during puberty
What is DiGeorge Syndrome?
Congenital immunodeficiency caused by a deletion on Chromosome 22
-Most common congenital cause of Thymic Aplasia
What is the characterization of DiGeorge Syndrome?
CATCH-22
- Cardiac anomalies
- Abnormal facies
- Thymic Aplasia
- Cleft palate
- Hypocalcemia
- Deletion on Chromosome 22
Where does the Trachea split into the Bronchi?
At the level of T4/5
Where are the four sites of Esophageal constrictions?
- Cricopharyngeus
- Aortic arch
- Tracheal bifurcation
- Diaphragm
Where does the Thoracic Duct originate from?
Cisterna chyli
-Largest lymph channel in the body
Where does the Thoracic Duct drain lymph from?
- Left superior quadrant
- Lower body
Where does the Thoracic Duct empty into?
Left Venous Angle (where Internal Jugular Vein and Subclavian Vein meet)
Where does the Aortic Arch lie while a person is standing?
It is transected by the transverse thoracic plane
Where does the Aortic Arch lie while a person is laying down?
It is superior to the transverse thoracic plane
Where does the Tracheal Bifurcation lie while a person is standing?
It is inferior to the transverse thoracic plane
Where does the Tracheal Bifurcation lie while a person is laying down?
It is transected by the transverse thoracic plane
Where does the Central Tendon of Diaphragm lie while a person is standing?
It is at the middle of the xiphoid process and T9-T10 intervertebral discs
Where does the Central Tendon of Diaphragm lie while a person is laying down?
It lies at the level of the xiphisternal junction and vertebra
