1.2.1 Mediastinum Flashcards
Describe the subdivisions of the medistinum.
Superior: sits above the sternal angle of louis
Inferior: subdivided into anterior, middle, and posterior
Middle: includes heart and pericardium
In what region of the mediastinum is the thymus located?
Anterior part of the superior mediastinum
From which arteries does the thymus recieve its arterial supply?
inferior thyroid and anterior intercostals
Thymoma, tumors of the thymus, can grow and affect what structures in the surrounding area of the body?
SVC, trachea, and occasionally other mediastinal structures
Which two veins come together, occurs bilaterally, to form the brachiocephalic vein?
Internal jugular vein and subclavian vein
Decribe the branching of the SVC as it travels distally from the heart?
Bifurcates into the R/L brachiocephalic, branch of internal jugular, branch of external jugular, called the subclavian vein, called the axillary vein, called the brachial vein
What are the 3 parts of the thoracic aorta?
Ascending - begins in pericardial sac and ascends behind sternal angle
Arch - lies behind manubrium in front of trachea
Descending - begins at sternal angle and descends just anterior to vertebral bodies
Describe the spatial relationship of the SVC, Aorta, R/L pulmonary arteries, trachea, and esophagus.
What are the first three branches off of the aorta?
Just remember your ABCS!
A - Arch of Aorta
B - Brachiocephalic
C - Left Common carotid
S - Subclavian
Describe the spatial relationship b/t the trachea and esophagus.
Trachea just anterior to esophagus
Where does the trachea typically branch into the primary/main bronchi (the carina of the trachea)?
The sternal angle or ~T4-T5
If a foreign object is inhaled, which main bronchi is typically occluded? Why?
The right main bronchus b/c it has a larger diameter and runs slightly more vertical
When the esophagus enters the superior mediastinum it is sandwiched b/t which two structures?
Trachea and vertebral column
What is the 8-10-12 rule?
The 8-10-12 rule refers to the vertebral position in which the three tubes pass through the diaphragm.
IVC passes through at the level of T8
Esophagus passes through at the level of T10
Aorta passes through at the level of T12
The phrenic nerve arises from which ventral rami?
C3, C4, C5
The phrenic nerve runs external to the fibrous pericardium on its way to innervating what structure?
The diaphragm
Identify the three structures.
What are the three different locations that pain originating from the diaphragm can be felt?
T7-10 anteriorly,
T11-12 posteriorly
reffered to cervial levels C3-5 due to phrenic innervation
What parasympathic nerve is responsible for supplying all thoracic organs and upper 2/3 of abdominal organs?
Vagus (CN X)
The right vagus stays posterior to the root of the lungs and descends along the posterior of what structure? Where does the left vagus run?
Right: posterior of the esophagus
Left: posterior to root of lungs, descends along the left lateral surface of the arch of the aorta and descends along anterior of esophagus
Where do the R/L recurrent larygeal nerves come off of the vagus? and, their position relative to the aorta and its branches?
Identify this nerve
What are the threee thoracic splanchnic nerves that innervate abdominal organs and their position relative to the vertebrae?
Greater splanchnic: T5-9
Lesser splanchnic: T10-11
Least splanchnic: T12
Where does the thoracic duct begin in the abdomen?
Cisterna chyli (level L1-L2)
The thoracic duct empties into the junction of which 2 veins?
Left subclavian and left internal jugular vein
Indentify these important structures
What is chylothorax?
Lymph in a pleural cavity (more than 50% of malignant etiologies)
Where does the azygous vein run? What are its two possible branches?
Runs cranially/caudally along the right side of the vertebral bodies
Hemizygos (inferior aspects along left side of the thoracic vertebrae) and accessory hemizygous (superior aspect of the left side of the thoracic vertebrae)
What are these three veins?
The arch of the azygous vein joins the SVC just superior to what structure?
The hilar region of the right lung
What is pancoast syndrome?
An apical brochogenic carcinoma (superior sulcus tumor) that can impinge on adjacent anatomical structures. This can lead to Horner’s syndrome– interruption of sympathetic innervation to head and neck resulting in ptosis (drooping of upper eye lid), myosis (constriction of pupil), and anhydrosis (reduced sweating) unilaterally). Pt may also present w/ neurovascular compromise for the arm with wasting, pain, or paraesthesia of the arm.
