Lecture 19

Question 1

In the superior mediastinum subdivision of the mediastinum, describe the contents of the retrosternal area and the pervertebral area

Answer 1

Retrosternal area: Great vessels (and their branches) and Thymus

Prevertebral area: Trachea, Esophagus, Thoracic duct, Sympathetic trunks, and Vagus nerves

Question 2

Describe the boundaries that create the 2 subdivisions of the mediastinum

Answer 2

Superior mediastinum: above the “horizontal line” (IV disc between T4 and T5 to sternal angle)

Inferior mediastinum: below the “horizontal line” (IV disc between T4 and T5 to sternal angle)

Question 3

In the Inferior mediastinum, state the subdivsion that the following belongs in.

Pericardium, Phrenic nerves, Pericardiacophrenic artery, Heart, and great vessels

Answer 3

Middle subdivision of the inferior mediastinum

Question 4

In the Inferior mediastinum, state the subdivsion that the following belongs in.

thymus, Fat, and lymph nodes

Answer 4

Anterior subdivision of the inferior mediastinum

Question 5

In the Inferior mediastinum, state the subdivsion that the following belongs in.

Esophagus, Thoracic duct, Aorta (and branches), Vagus Nerves, Sympathetic trunks, and the Azygos system of veins

Answer 5

Posterior subdivision of the inferior medistinum

Question 6

Describe the blood supply and innervation of the thymus.

Answer 6

It’s blood supply comes from the thoracic artery (it’s anterior mediastinal arteries that branch off of it)

Parasympathetic innervation comes from the vagus nerves, while the Sympathetic innervation comes from the cardiac sympathetic plexus

Question 7

What does the pericardium enclose, and what is is it composed of?

Answer 7

The pericardium encloses the heart

It is composed of an arterial mesocardium and a venous mesocardium

Question 8

State the blood and nerve supply of the pericardium (3 each)

Answer 8

Blood supply:
Pericardial arteries

Pericardiacophrenic arteries

Musculophrenic arteries

Nerve supply:
CN X

Phrenic Nerve

Sympathetic trunk

Question 9

State the 3 ligaments (4 if you get specific with one of them) that are attached to the pericardium

Answer 9

Ligaments:
The fibrous portion of the pericardium is fused with the central tendon of the diaphragm

The pericardiacophrenic ligament is fused with the sternum

superior/inferior sternopericardial ligaments

Question 10

Describe the route of the esophagus (Include it’s relation to the trachea, aorta, and spinal level that it pierces the diaphragm)

Answer 10

From the base of the neck it runs left of the midline, midline at the level of the aortic arch, and then continues to run left of the midline again

Runs behind the trachea

Runs to the right of the aorta

Passes through diaphragm at T10 level

Question 11

Describe the blood supply and innervation (include the voluntary and involuntary portions of it) of the esophagus

Answer 11

Blood Supply:
Bronchial artery, Thoracic aorta, left gastric artery, and left inferior phrenic artery

Innervated by the esophageal plexus (continuation of the posterior pulmonary plexus that is formed by the right and left vagus nerves
Upper 3rd is voluntary muscle and the lower 2 3rds are involuntary

Question 12

Describe the pathway of the thoracic aorta and related landmarks

Answer 12

It begins a the T4 level, and runs down left of the midline until it pierces the diaphragm at T12 level (abdominal aorta after that)

Question 13

In the thoracic cavity, the following are all branches of what vessel?

(pericardial, bronchial, esophageal, intercostal, subcostal, and superior phrenic areteries)

Answer 13

The thoracic aorta

Question 14

Describe the origin, pathway, and termination of the azygos vein

Answer 14

Azygos Vein: formed by the union of the right ascending lumbar vein and the right subcostal vein, which occurs below the diaphragm

Ascends along the right side of the thoracic vertebral column and arches over the root of the right lung and enters the superior vena cava

Question 15

Describe the origin, pathway, and termination of the hemiazygos vein

Answer 15

Hemiazygos vein: formed by the union of the left ascending lumbar vein and the left subcostal vein, below the diaphragm

Pierces the diaphragm and ascend along the left side of the vertebral bodies to the level of T9

Crosses the vertebral body and empties into the azygos vein

Question 16

Describe the origin, pathway, and termination of the accessor hemiazygos vein

Answer 16

Accessory hemiazygos veins: receive blood from the superior intercostal vein and from the left intercostal veins 4-8

Runs runs in the left side of the upper thoracic vertebral bodies, crosses the vertebral body and empties into the azygos vein

Question 17

The following all have what association in common?

right intercostal veins 5-11
superior intercostal vein
hemiazygos vein
accessory hemiazygos vein

Answer 17

They are all tributaries of the azygos vein

Question 18

List the 5 major groups of thoracic lymph nodes

Answer 18

Parasternal nodes

Posterior intercostal nodes

Diaphragmatic nodes

Posterior mediastinal nodes

Brachiocephalic nodes

Question 19

Describe the location, source of lymph, and drainage pattern of the Parasternal nodes

Answer 19

The parasternal nodes lie behind the sternum (along the internal thoracic artery)

they receive lymph from the mammary gland

they drain into the parasternal lymph channel

Question 20

Describe the location, source of lymph, and drainage pattern of the posterior intercostal nodes

Answer 20

The Posterior intercostal nodes lie in the posterior intercostal space between the heads of ribs

they receive lymph from the paravertebral regions

The left and lower right portions of these nodes drain into the thoracic duct, while the upper right portion of these nodes drains into the right lymphatic duct

Question 21

Describe the location, source of lymph, and drainage pattern of the diaphragmatic nodes

Answer 21

Diaphragmatic nodes lie on the upper surface of the diaphragm

they receive lymph from the diaphragm, pericardium, and upper surface of the liver

They drain to the parasternal and posterior mediastinal nodes

Question 22

Describe the location, source of lymph, and drainage pattern of the posterior mediastinal nodes and the brachiocephalic nodes

Answer 22

Posterior mediastinal nodes lie along the esophagus and descending thoracic aorta

Brachiocephalic nodes lie along the brachiocephalic veins

Question 23

Name the major parasympathetic supply to the contents of the thoracic cavity.

Answer 23

The Vagus Nerve (CN 10)

Question 24

Trace the route of the vagus nerves and their branches (include the left and right recurrent laryngeal nerve branches)

Answer 24

Its cardiac branches, pulmonary, and esophageal branches all end at their respective plexuses

The left recurrent laryngeal nerve from the left vagus, hooks around the arc of the aorta to the left of the ligamentum arteriosum

The right recurrent laryngeal nerve from the right vagus, hooks around the subclavian artery

Question 25

Describe the origin and route of the phrenic nerves

Answer 25

Arises in the neck from the vental rami of the C3-C5 (C4 donates the major contribution) Passes anterior to the pulmonary root of each side (only nerve that does this)

Question 26

What is the only motor nerve for the diaphragm?

Answer 26

the phrenic nerve

Question 27

The phrenic nerve supplies sensory fiber to what structures? (4 of them)

Answer 27

The pericardium mediastinal pleura pleural covering of the diaphragm peritoneal coverings of the diaphragm

Question 28

Describe the type of pain that is commonly associated with phrenic nerve pain.

Answer 28

Pain from the phrenic nerves is usually felt in the base of the neck and the tip of the shoulder

Question 29

What accompanies the phrenic nerves along it's route from the neck, into the throacic cavity?

Answer 29

The phrenic nerve is accompanied by pericardiacophrenic arteries (which are branches of the internal thoracic arteries)

Question 30

Describe the attachments of the respiratory diaphragm (4 of them)

Answer 30

Ribs TV12 Distal end of the sternum Central tendon

Question 31

Describe the central tendon and its relation to the crura and the openings of the diaphragm.

Answer 31

It is a "Y shaped" tendon that attaches to lumbar vertebrae via crura It is pierced by 3 openings (caval foramen, esophageal hiatus, and aortic hiatus) The right part is the largest part and the left part is the smallest part

Question 32

List structures that pierce the diaphragm, including accompanying nerves and the vertebral levels at which they penetrate the diaphragam (3 of them)

Answer 32

At T8, the caval foramen allows the passage of the inferior vena cava, accompanied by the right phrenic nerve At T10, the esophageal hiatus allows the passage of the esophagus, acccompanied by the vagus nerves At T12, the Aortic hiatus allows the passage of the Aorta, accompanied by the greater splanchnic nerve