Overview of the Thoracic Cavity

Question 1

3 main spaces of the thorax

Answer 1

The right and left pleural cavities and the mediastinum (the area between the right and left pleural cavities).

Question 2

How many vertebrate in the thoracic cavity? How many ribs? What

Answer 2

12 Thoracic vertebrate, 12 ribs– 7 true ribs (articulate directly with the sternum anteriorly), 3 false ribs (indirectly articulate with sternum via the costal arch), 2 floating ribs

Question 3

How do the ribs function in breathing

Answer 3

Ribs are directed inferiorly as they move back to front, so as you breath they are lifted one on another, causing the thoracic cavity to expand in volume, allowing for air to flow in.

Question 4

The 3 parts of the sternum

Answer 4

Manubrium, body, xiphoid process

Question 5

Sternal Angle

Answer 5

Articulation between the manubrium and the body. Aka the Angle of Louis.

This landmark is used as a starting point for counting ribs (second rib)

Corresponds with vertebrate T4 and T5

Question 6

Intercostal muscles

Answer 6

External, Internal, and Innermost

Question 7

Differences in the fibers of the intercostal muscles

Answer 7

• External fibers: run inferiorly/medially (putting your hands in your pocket)
• Internal fibers: run 90 degrees to the external– superiorly/ medially.
• Innermost fibers: run up and down

Question 8

Are the intercostal muscles complete all the way around the intercostal spaces?

Answer 8

No

Question 9

Describe the blood supply to the anterior thoracic wall

Answer 9

Anterior intercostal artery (branch off of the internal thoracic and musculophrenic arteries). There is also the supreme thoracic artery.

Question 10

Describe the blood supply to the posterior thoracic wall

Answer 10

Supplied by posterior intercostals which are branches of the aorta and costocervical trunk

Question 11

Venous drainage of the thoracic wall

Answer 11

Brachiocephalic and azygos veins

Question 12

Innervation of thoracic walls

Answer 12

Intercostal muscles are innervated by ventral rami of thoracic nerves (intercostal nerves) T1-T11 (there are 11 intercostal spaces)

Question 13

Where should needles and items be inserted in the intercostal space?

Answer 13

Above the rib, because the nerve runs in the grove below the rib. The neurovascular bundle is related to the inferior part of the corresponding ribs.

Question 14

Where does the first rib articulate?

Answer 14

The manubrium

Question 15

The top of the manubrium (jugular notch) intersects where? What does this mean?

Answer 15

Intersects the second thoracic vertebrate posteriorly which means that some of the lung actually projects into the neck.

Question 16

Xiphoid sternum intersects with which thoracic vertebrate?

Answer 16

The IX

Question 17

What is the range of vertebrate that the diaphragm spans?

Answer 17

T9-L2 (which means most of the abdominal structures are covered by ribs)

Question 18

4 compartments associated with the mediastinum

Answer 18

The heart is the MIDDLE MEDIASTINUM, which means the space in front of it is the ANTERIOR MEDIASTINUM, the space above it is the SUPERIOR MEDIASTINUM, and behind it is the POSTERIOR MEDIASTINUM

Question 19

Contents and location of the Superior Mediastinum

Answer 19

It is the space above the Sternal Angle.

Contains:

(1) Aortic Arch
(2) Brachiocephalic trunk
(3) Left common carotid a.
(4) Left subclavian a.
(5) Superior Vena Cava
(6) Brachiocephalic v.
(7) Thymus
(8) Trachea/Esophagus
(9) Vagus and Phrenic n.
(10) Recurrent laryngeal
(11) Thoracic Duct

Question 20

Pleural cavities house what?

Answer 20

Lungs

Question 21

Main function of cavities

Answer 21

Lubrication (via serous fluid) of structures which move a lot. (Structure is like putting fist in a balloon)

Question 22

Visceral vs. Parietal Layer

Answer 22

Visceral- closest to structure
Parietal- furthest from structure

Continuous to each other at the point of entry

Question 23

Subclavian artery and vein are separated by what?

Answer 23

Anterior scalene.

Question 24

The right internal jugular and subclavian drain into what?

Answer 24

The right brachiocephalic vein, which drains into the superior vena cava.

Question 25

What does the left brachiocephalic have to cross in order to enter the Superior Vena Cava?

Answer 25

The superior mediastinum

Question 26

Contents of the Middle Mediastinum

Answer 26

Pericardium, heart and great vessels, root of lungs, phrenic nerves

Question 27

Contents of the Anterior Mediastinum

Answer 27

Area in front of heart, behind sternum.

Areolar tissue and lymph nodes

Question 28

Compared to the arteries, the veins of the great vessels are most…

Answer 28

Anterior

Question 29

As the great vessels go off to the left of the aorta, they come off…

Answer 29

Posteriorly

Question 30

The difference between the vagus and phrenic in cross-section?

Answer 30

Phrenic is anterior to vagus.

The vagus rides nearer to the esophagus to get to the abdominal cavity so rides posteriorly.

Phrenic runs on the surface of the pericardium of the heart, and rides with the brachiocephalic.

Question 31

Contents of the posterior mediastinum

Answer 31

(1) Descending aorta
(2) Azygos and hemiasygos v.
(3) Esophagus
(4) Vagus n.
(5) Thoracic Splanchnic n.
(6) Thoracic Duct