Anatomy Topic 2 Case 3 Flashcards
What is the mediastinum?
- Broad central partition
- That separates the two laterally placed pleural cavities
What are the anterior, posterior, superior and inferior boundaries of the mediastinum?
- Anterior: Sternum
- Posterior: Vertebrae
- Superior: Superior Thoracic Aperture
- Inferior: Diaphragm
What is the name of the plane that divides the mediastinum into the superior and inferior mediastinum and where is this plane located?
- Transverse Thoracic Plane
- Between sternum and intervertebral disc of T4 and T5
What are the anterior, posterior, superior and inferior boundaries of the superior mediastinum?
- Anterior: Manubrium of Sternum
- Posterior: T1 - T4
- Superior: Superior Thoracic Aperture
- Inferior: Transverse Thoracic Plane
Identify 10 structures located within the superior mediastinum
- Arch of the Aorta
- Superior Vena Cava
- Brachiocephalic Veins
- Left superior Intercostal Vein
- Vagus Nerve
- Left Recurrent Branch of Vagus Nerve
- Phrenic Nerve
- Thymus
- Trachea
- Oesophagus
Identify the anterior, posterior, superior and inferior boundaries of the anterior mediastinum
- Anterior: Body of Sternum
- Posterior: Pericardial Sac
- Superior: Transverse Thoracic Plane
- Inferior: Diaphragm
Identify 5 structures located within the anterior mediastinum
- Mediastinal branch of internal thoracic arteries
- Lymph Nodes
- A portion of the Thymus
- Fat and Connective Tissue
- Sternopericardial Ligament
Identify the anterior, posterior, superior and inferior boundaries of the posterior mediastinum
- Anterior: Bodies of lower thoracic vertebrae
- Posterior: Pericardial Sac
- Superior: Transverse Thoracic Plane
- Inferior: Diaphragm
Identify 6 structures located within the posterior mediastinum
- Thoracic Aorta
- Azygos System
- Thoracic Duct and its associated lymph nodes
- Oesophagus and its associated nerve plexus
- Sympathetic Trunks
- Thoracic Splanchnic Nerves
Identify the anterior, posterior, superior and inferior boundaries of the posterior mediastinum
- Anterior: Anterior Mediastinum
- Posterior: Posterior Mediastinum
- Superior: Transverse Thoracic Plane
- Inferior: Diaphragm
Identify 3 structures located within the middle mediastinum
- Heart
- Origins of Great Vessels
- Various nerves and smaller vessels
Identify the two parts of the aorta
- Arch of the aorta
- Descending aorta
Identify the pathway taken by the arch of the aorta
- Emerges from pericardial sac
- Courses upward, backward and to the left
- Through superior mediastinum
- Ending on left side of vertebra T4-T5
Identify the first branch of the arch of the aorta
- Brachiocephalic Trunk
Identify the position and pathway of the first branch of the arch of the aorta
- Anterior to the other branches
- Ascends posteriorly and to the right
Identify the two branches of the first branch of the arch of the aorta and what they supply
- Right common carotid artery, supplies right side of head
- Right subclavian artery, supplies right side of neck
Identify the second branch of the arch of the aorta and what does it supply?
- Left common carotid artery
- Left side of the head and neck
Identify the position and pathway of the second branch of the arch of the aorta
- Left and posterior to the brachiocephalic trunk
- Ascends along the left side of the trachea
Identify the third branch of the arch of the aorta and what does it supply?
- Left subclavian artery
- Left upper limb
Identify the position and pathway of the third branch of the arch of the aorta
- Left and posterior to the left carotid artery
- Ascends along the left side of the trachea
What vertebral levels does the thoracic aorta descend between?
Where does it penetrate the diaphragm?
- T4 and T12
- Aortic Hiatus
Identify the 9 branches of the thoracic aorta?
- Pericardial Branches
- Bronchial Branches
- Oesophageal Branches
- Mediastinal Branches
- Posterior Intercostal Arteries (9 pairs in total supplying lower 9 intercostal spaces)
- Superior Phrenic Arteries (dividing into musculophrenic and pericardiacophrenic arteries)
- Subcostal arteries
Where are the brachiocephalic veins located?
- Middle mediastinum
- Posterior to thymus
- Between the internal jugular and subclavian veins
The left brachiocephalic vein crosses the midline to join with the right to form what structure?
- Superior vena cava
Identify 5 veins that the left superior intercostal vein receives
- Second, third and fourth intercostal veins
- Left bronchial vein
- Left pericardiacophrenic vein
Describe the pathway taken by the left superior intercostal vein
- Passes over left side of thoracic arch
- Lateral to vagus nerve and medial to phrenic nerve
- Before entering the left brachiocephalic vein
Where does the azygos vein arise?
- Opposite L1 or L2
- Between right ascending lumbar vein and right subcostal vein
Where does the azygos vein enter the thorax?
- Aortic Hiatus
- To the right of the Thoracic Duct
At what level does the azygos vein join the superior vena cava?
- T4
Where does the hemiazygos vein arise?
- Between the left ascending lumbar vein and left subcostal vein
Where does the hemiazygos vein enter the thorax and at what vertebral level does it cross the vertebral column?
- Left Crus
- Through posterior mediastinum to approximately T9
Where does the accessory hemiazygos vein descend?
- On left side of superior portion of middle mediastinum
- To approximately T8
- Where it crosses the vertebral column
Which divisions of the mediastinum do the vagus nerves pass through?
- Superior and posterior
What is the function of the vagus nerves?
- To provide parasympathetic innervation to the thoracic viscera
- To carry afferents from the thoracic viscera
Describe the pathway taken by the right vagus nerve from the superior mediastinum
- Enters superior mediastinum between right brachiocephalic vein and brachiocephalic trunk
- Descends in a posterior direction towards the trachea
- Passes posteriorly to the root of the right lung to reach the oesophagus
Describe the pathway taken by the left vagus nerve from the superior mediastinum
- Enters superior mediastinum and passes the left side of the aortic arch
- Descends in a posterior direction to the root of the right lung to reach the oesophagus
The left vagus nerve gives rise to which nerve?
- Left recurrent laryngeal nerve
- Which passes inferiomedially to the arch of the aorta
- And terminates superiorly in the larynx
What is the function of the phrenic nerve?
Somatic innervation to the:
- Mediastinal pleura
- Fibrous pericardium
- Parietal layer of serous pericardium
How do the phrenic nerves leave the thorax?
- Right phrenic nerve passes through with the inferior vena cava
- Left phrenic nerve pierces the diaphragm near the apex of the heart
Where does the thoracic duct begin?
- Lymphatic trunks in the abdomen at L2
- Referred to as the cisterna chyli
How does the thoracic duct enter the thorax?
- Through the aortic hiatus
- Posterior to the aorta
- Into the posterior mediastinum
What occurs at the thoracic level T5
- Moves to the midline
The thoracic duct is joined by which veins
- Left jugular trunk
- Left subclavian trunk
Describe the structure of the sympathetic trunks
- Two parallel cords
- Superiorly they run anterior to the vertebral bodies
- Inferiorly the run medial in position
- Punctuated by 11 or 12 ganglia
- Connected to adjacent spinal nerves by white and grey rami communicantes
Identify the two types of branches given off by the ganglia
- Upper five ganglia = postganglionic sympathetic fibres
- Lower seven ganglia = preganglionic sympathetic fibres
Where does the pulmonary trunk arise from?
- Conus arteriosus of the right ventricle
At which level does the pulmonary trunk divide into left and right pulmonary arteries?
- T5 and T6
