Mediastinal Spaces Flashcards
A cavity formed by the lungs on either side. Lungs are a boundary, not a content
Mediastinum
Where does Superior transition to Inferior?
Begins at the first rib, at the Sternal Angle of Louis. Runs across and ends at the intervertebral disc between T4 and T5.
-A content of the Superior Mediastinum
-Degenerates into fat during the teenage years.
-The most superficial structure you see when removing the anterior chest wall
Thymic Remnant
What are the contents of the Superior Mediastinum? (14)
-Thymic Remnant
-Brachiocephalic Veins & Superior Vena Cava
-Aortic Arch and its branches (Brachiocephalic Trunk, LCC, Subclavian artery)
-Trachea (Thoracic Portion)
-Upper thoracic portion of the esophagus
-Termination of the Thoracic Duct & Right Lymphatic Duct
-Vagus Nerves & Phrenic Nerves, Recurrent Laryngeal Nerve
Carries most of the lymphatic drainage for your body. Lymph is left over after gas exchange occurs.
-Begins in the Cisterna Chyli (right by Right Diaphragmatic Crus)
-Passes through Aortic Hiatus!!, runs up to about C7, then turns and runs behind L IJ, and terminates at the point where the Left Subclavian Vein and the L IJ make the L Brachiocephalic Vein
Thoracic Duct
A dilated sac that holds lymph. Lies right by the Right Diaphragmatic Crus.
-Becomes the Thoracic Duct
Cisterna Chyli
Drains lymph for the Right upper extremity, right trunk, right neck/head.
-Drains at the point where the Right IJ and Right Subclavian Veins join to make the Right Brachiocephalic Vein.
Right Lymphatic Duct
The Left Recurrent Laryngeal Nerve curves around the ________.
Aortic Arch
The Right Recurrent Laryngeal Nerve curves around the ________.
Right Subclavian Artery
Contents of the Anterior Compartment of the Inferior Mediastinum (3)
-Lower portion of the Thymus (base - most of it is in superior)
-Internal Thoracic Vessels (run on either side of the sternum)
-Lymph Nodes
Branch of the Subclavian Artery, courses down the side of the sternum until the Costal Margin. Then, bifurcates into Musculophrenic Branch (follows costal margin laterally) and the Superior Epigastric Artery (goes straight down to Abdomen)
Internal Thoracic Artery
What artery is an example of Vena Communicantes: 2 veins with 1 Artery
Interal Thoracic Artery
Muscle with branches coming off going to the ribs
-Not really part of mediastinal space, usually wrapped up in peritoneum
Transverse Thoracis Muscle
Contents of the Middle Compartment of the Inferior Mediastinum (5)
-Heart, Coronary Vessels, and the Pericardium
-Branches of the Great Vessels (Ascend Aorta, Pulm Trunk, SVC/IVC, and termination of the Pulmonary Veins) where they begin/terminate in the heart.
-Bifurcation of the Trachea into Mainstem Bronchi
-Arch (and termination in the SVC) of the Azygos Vein
-Phrenic Nerves within the pericardium
Acts as a bridge to the Left Mainstem Bronchus, Left Pulmonary Artery and Veins. Run underneath this.
Aortic Arch
Acts as a bridge to the Right Mainstem Bronchus, Right Pulmonary Artery, and Right Pulmonary Veins (usually 2)
Arch of the Azygos Vein
Entwine themselves with the pericardial sac.
-Runs with the Pericardiocophrenic Arteries (branch of the Internal Thoracic Artery) that supplies the diaphragm with blood
Phrenic Nerves (Pericardial portion)
Contents of the Posterior Compartment of the Inferior Mediastinum (7)
-Thoracic Aorta (Arch to Aortic Hiatus)
-Esophagus
-Vagus Nerves (Esophageal Plexus after Recurrent Laryngeal branches off)
-Thoracic Duct (runs with the Azygos and Esophagus)
-Azygos Vein (right) and Hemiazygos/Accessory Hemiazygos Veins (left)
-Origination of the Greater (T5-T9), Lesser (T10-T11), and Least (T12) Splanchnic Nerves
-Posterior Mediastinal Lymph Nodes
Offer alternative pathways for blood to lighten the load on the IVC.
Azygos, Hemiazygos, and Accessory Hemiazygos Veins
After the recurrent laryngeal nerve branches off, these continue on with the esophagus. Forms this after passing the Mainstem bronchi. Covers the Esophagus.
-Before you hit the Diaphragm, reforms into nerves called the Anterior and Posterior Vagal Trunks (provide sensory input to the esophagus)
Esophageal Plexus
Left Vagus Nerve forms the _________ Vagal Trunk
Anterior Vagal Trunk
Right Vagus Nerve forms the _________ Vagal Trunk
Posterior Vagal Trunk
The Vagus runs all the way to about __________, then it runs out and parasympathetic nerves take over.
L Colic Flexure
Like the Transverse thoracis muscle, these are covered with peritoneum, so are not counted as a content of the mediastinal space (but are found in the Posterior Compartment of the Inferior Mediastinum)
Sympathetic Chains (2)
Begins below the diaphragm (as the Right Ascending Lumbar Vein), passes through the Aortic Hiatus, and continues up to terminate via its arch in the SVC.
-Helps the IVC get all the blood back to the heart.
Azygos Vein
Formed from the Left Ascending Lumbar Vein passing above the Diaphragm.
-Anastomoses with the Accessory Hemiazygos (from above) Veins to give off a Communicating Vein that runs behind the aorta/esophagus to join the Azygos Vein on the other side
-Blood flows from Left to Right.
-Hemiazygos + Accessory → Communicating Vein → Azygos → SVC
Hemiazygos Vein
Supplies preganglionic SNS innervation to the upper 1/3rd of Abdominal Viscera
-Projects to the Celiac Ganglion & Adrenal Medulla
-T5-T9
Greater Splanchnic Nerve
-Hides below the diaphragm, goes into the Costodiaphragmatic Recess
Supplies preganglionic SNS innervation to the middle 1/3rd of Abdominal Viscera.
-Projects to the Superior Mesenteric Ganglion
-T10-T11
Lesser Splanchnic Nerve
-Hides below the diaphragm, goes into the Costodiaphragmatic Recess
Supplies preganglionic SNS innervation to the lower 1/3rd of Abdominal Viscera.
-Projects to the Inferior Mesenteric Ganglion
-T12
Least Splanchnic Nerve
Which structures are found in the Superior AND Posterior Compartments of the Mediastinum?
-Thoracic Duct
-Esophagus
-Vagus Nerve
Which structures are found in the Superior AND Middle Compartment of the Mediastinum?
-Phrenic Nerve
-Trachea
Which structure is found in the Superior AND Anterior Compartment of the Mediastinum?
Thymus Gland
Which structure is found in the Superior, Middle, AND Posterior Compartment of the Mediastinum?
Aorta
-Ascending: Middle portion of Inferior
-Arch: Superior
-Descending: Posterior portion of Inferior
