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3 main spaces of the thorax

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


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

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


How do the ribs function in breathing

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.


The 3 parts of the sternum

Manubrium, body, xiphoid process


Sternal Angle

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


Intercostal muscles

External, Internal, and Innermost


Differences in the fibers of the intercostal muscles

-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


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



Describe the blood supply to the anterior thoracic wall

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


Describe the blood supply to the posterior thoracic wall

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


Venous drainage of the thoracic wall

Brachiocephalic and azygos veins


Innervation of thoracic walls

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


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

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.


Where does the first rib articulate?

The manubrium


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

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


Xiphoid sternum intersects with which thoracic vertebrate?

The IX


What is the range of vertebrate that the diaphragm spans?

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


4 compartments associated with the mediastinum

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


Contents and location of the Superior Mediastinum

It is the space above the Sternal Angle.

(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


Pleural cavities house what?



Main function of cavities

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


Visceral vs. Parietal Layer

Visceral- closest to structure
Parietal- furthest from structure

Continuous to each other at the point of entry


Subclavian artery and vein are separated by what?

Anterior scalene.


The right internal jugular and subclavian drain into what?

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


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

The superior mediastinum


Contents of the Middle Mediastinum

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


Contents of the Anterior Mediastinum

Area in front of heart, behind sternum.

Areolar tissue and lymph nodes


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



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



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

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.