Overview of the Thoracic Cavity Flashcards
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?
No
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.
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
Pleural cavities house what?
Lungs
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…
Anterior
As the great vessels go off to the left of the aorta, they come off…
Posteriorly
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.
Contents of the posterior mediastinum
(1) Descending aorta
(2) Azygos and hemiasygos v.
(3) Esophagus
(4) Vagus n.
(5) Thoracic Splanchnic n.
(6) Thoracic Duct
