Thorax 10: Superior, Anterior, Posterior Mediastinum

Question 1

Superior mediastinum

Answer 1

The top section of the mediastinum, running from the superior thoracic inlet to the transverse thoracic plane

Question 2

Transverse thoracic plane

Answer 2

The plane at the sternal angle

Question 3

What are the structures found in the superior mediastinum?

Answer 3

Thymus, trachea, esophagus, brachiocephalic veins, SVC, aortic arch, brachiocephalic trunk, left subclavian and common carotid arteries; vagus nerve, phrenic nerve, cardiac plexus, left recurrent laryngeal nerve, thoracic duct, left superior intercostal vein

Question 4

Thymus

Answer 4

A fat lymphoid organ of loosely organized collection of interconnected lymphoid lobules found in the anterior and superior mediastinum that mostly involutes in adults. It is the site of T-cell maturation

Question 5

How are T-cells activated inside the thymus?

Answer 5

Thymic interdigitating cells present normal self components to maturing T-cells, which may activate some T-cells

Question 6

Clonal deletion

Answer 6

The apoptosis of self-activating T-cells (T-cells that activate to self-antigens in the thymus)

Question 7

How are T-cells activated outside the thymus?

Answer 7

They are exposed to antigens by antigen presenting cells

Question 8

How does the thymus develop?

Answer 8

Pocketing of epithelium cells of the 3rd pharyngeal arches. Neural crest cells are involved

Question 9

What is the role of the epithelium in thymus development?

Answer 9

They make the blood-thymus barrier and help T-cells develop

Question 10

Thymus cortex

Answer 10

The outer layer of the thymus, formed by T-lymphocytes, thymic epithelial cells, and thymic dendritic cells

Question 11

Thymus medula

Answer 11

The inner layer of the thymus

Question 12

Hassal’s corpuscles

Answer 12

Onion-like structures in the thymus that are mostly degenerative

Question 13

Thymus capsule

Answer 13

The layer on the outside of the thymus cortex

Question 14

Why is the blood-thymus barrier important?

Answer 14

It keeps antigens out until T-cells are mature

Question 15

Lymphatics in the thymus

Answer 15

There are none

Question 16

Septae

Answer 16

Insertions into the thymus cortex where arteries enter the thymus

Question 17

What type of cells form the blood-thymus barrier?

Answer 17

Epithelio-reticular cells

Question 18

What nerves are found in the superior mediastinum?

Answer 18

Phrenic nerves, left vagus nerve, left recurrent laryngeal, right vagus nerve

Question 19

Where is the left vagus nerve located?

Answer 19

Lateral to aortic arch

Question 20

Where is the right vagus nerve located?

Answer 20

Dorsal to the aortic arch, on trachea and esophagus

Question 21

Where is the left recurrent laryngeal nerve located?

Answer 21

Medial to aortic arch

Question 22

What is found in the anterior mediastinum?

Answer 22

Thymus, sternopericardial ligaments, branches of internal thoracic vessels, lymph nodes

Question 23

What is found in the posterior mediastinum?

Answer 23

Thoracic aorta and its branches, azygous system, sympathetic trunk, thoracic splanchnic nerves, vagus nerves, esophagus, thoracic duct, lymph nodes

Question 24

With regards to the spinal cord, where does the esophagus run?

Answer 24

C6 - T11

Question 25

Where does the esophagus enter the thoracic cavity?

Answer 25

Superior thoracic aperture

Question 26

Where does the esophagus leave the thoracic cavity?

Answer 26

Esophogeal hiatus of the diaphragm (at T10)

Question 27

What innervates the esophagus

Answer 27

Esophageal plexus

Question 28

What supplies blood to the esophagus?

Answer 28

Esophageal branches of the aorta

Question 29

What is the venous drainage of the esophagus?

Answer 29

Azygous veings; left gastric vein in the abdomen

Question 30

From top to bottom, what are the four impressions on the esophagus?

Answer 30

Aortic arch, left main bronchus, left atrium, diaphragm

Question 31

Of the vagus nerves, which one is posterior to the esophagus and which one is anterior?

Answer 31

Left is anterior and right is prosterior

Question 32

What sympathetic nervs go to the esophagus?

Answer 32

Sympathetic nerves starting at T1-T5

Question 33

What are the main branches of the thoracic aorta?

Answer 33

Pericardial, bronchial, esophageal, prosterior intercostal, subcostal , superior phrenic

Question 34

Artery of Adamkiewicz

Answer 34

Largest anterior medullary feeder artery to the anterior spinal artery; it is the most important supply to the lower thoracic spinal cord

Question 35

Azygous vein

Answer 35

A vein that originates in the abdomen on the right side and drains to the vena cava by arching over the root of the right lung

Question 36

Hemiazygous vein

Answer 36

A vein on the lower left side of the thoracic cavity that originates in the abodem. It drains into the azygous vein at T9

Question 37

Accessory hemiazygous vein

Answer 37

A vein on the upper left side of the thoracic cavity that drains into the azygous vein at intercostal spaces 5-8

Question 38

What is the order of tumor spread from the lungs to other organs?

Answer 38

Segmental bronchi -> lobar bronchi -> interlobal bronchi -> hilar bronchi -> mediastinal nodes -> supraclavicular and sternal notch nodes

Question 39

Where is the cardiac plexus located?

Answer 39

Anterior to the bifurcation of the trachea, posterior to the aortic arch, superior to the pulomary trunk

Question 40

Where is the pulmonary plexus located?

Answer 40

Anterior and posterior to the roots of the lungs

Question 41

What types of nerve innervate the lungs?

Answer 41

Visceral motor and nonsensory visceral afferents

Question 42

From outer to inner, what are the layers between the outside of the pericardium and the heart?

Answer 42

Parietal layer of serous pericardium -> fibrous pericardium -> pericardial cavity -> visceral layer of serous pericardium -> subepicardial fat -> myocardium -> endocardium

Question 43

How do we count ribs?

Answer 43

We can't palpate the first rib because it's under the clavicle, so we start counting from the second rib

Question 44

What is the surface projection of the apex of the heart?

Answer 44

5th intercostal space to the left at the midclavicular line

Question 45

What is the surface projection of the the right atrium of the heart?

Answer 45

3rd costal cartilage, one finger to the right of the sternum

Question 46

What is the surface projection of the left atrium of the heart?

Answer 46

2nd intercostal space on the left, midway to the midclavicular line

Question 47

What is the surface projection of the right ventricle of the heart?

Answer 47

The junction of the 6th costal cartilage and the sternum

Question 48

Where can we best hear the tricupsid valve?

Answer 48

Just to the left of the lower part of the sternum near the fifth intercostal space

Question 49

Where can we best hear the mytrial valve?

Answer 49

Just over the apex of the heart; at the 5th intercostal space to the left at the midclavicular line

Question 50

Where can we best hear the pulmonary valve?

Answer 50

Over the medial end of the left second intercostal space

Question 51

Where can we best hear the aortic valve?

Answer 51

Over the medial end of the right second intercostal space

Question 52

What is the surface projection of the apex of the pleural sac?

Answer 52

Just above the median third of the clavicle

Question 53

Where does the pleural sac end on the midclavicular line?

Answer 53

Rib 8

Question 54

Where does the pleural sac end on the midaxillary line?

Answer 54

Rib 10

Question 55

Where does the pleural sac end on the spine?

Answer 55

Rib 12

Question 56

Where does the lung end during quiet respiration on the midclavicular line?

Answer 56

Rib 6

Question 57

Where does the lung end during quiet respiration on the midaxillary line?

Answer 57

Rib 8

Question 58

Where does the lung end during quiet respiration on the spine?

Answer 58

Rib 10