Superior and Posterior Mediastina Flashcards
Be able to list/identify the various components of each region of the superior mediastinum.
Retrosternal region: thymus, left brachiocephalic v., superior portion of the superior vena cava; Intermediate reion: aortic arch, brachiovcephalic trunk, left common carotid artetry, left subclavian artery; Prevertebral region: trachea, esophagus, thoracic duct, left recurrent laryngeal nerve.
What is the boundary between the superior and inferior mediastina?
The sternal angle
Why is the sternal angle important clinically?
It represents the level at which the trachea bifurcates as well as the level at which the great vessels leave the heart.
Between what two vertebrae does a line drawn horizontally from the sternal angle
posteriorly pass?
T4/T5
What organ is found in the anterior mediastinum - in childhood?
The thymus
What replaces this organ it in the adult?
Fat and connective tissue
What structures are found only in the right aspect of the posterior mediastinum?
Azygous vein
What are found only in the left posterior mediastinum?
Hemiazygous and accessory hemiazygous veins, aorta.
Which structures would be found on both sides of the posterior mediastinum?
Posterior intercostal aa., intercostal nn., intercostal vv., sympathetic trunk, paravertebral ganglia, rami communicans, splancnic nn., and vagus nn.
Which specific vessels drain the intercostal spaces of the posterior thoracic wall?
Intercostal vv.
What system do they form?
The azygous system
What is the typical pattern of this system?
Broken H
How is the superior vena cava formed?
The union of the left and right brachiocephalic vv.
What vessels form the brachiocephalic vv.?
The union of the internal jugular vv. with the subclavian vv. on the left and right sides.
In which thoracic division(s) is the thoracic duct located?
The posterior (on it’s way from the abdomen) AND superior (as it termninates) mediastina.
Where does the thoracic duct begin?
At the cysterna chyli in the upper region of the abdomen.
Where does the thoracic duct terminate?
At the junction of the left internal jugular and left subclavian vv.
How does the internal thoracic aa terminate?
Musculophrenic a (lateral to diaphragm)
Superior epigastric a (medial to rictus sheath)
Esophageal plexus contributions
Left vagus –> anterior vagus
Right vagus –> posterior vagus
Phrenic n runs ____ to root of lung
Vagus n runs ____ to root of lung
Phrenic anterior
Vagus posterior
Right recurrent laryngeal branches where?
Left recurrent laryngeal branches where?
Right at subclavian artery
Left at ligamentum arteriosum
