Thorax, Pleural Cavity, Lungs Flashcards
What does the thorax protect?
Heart, lungs, liver on the right, spleen on the left, among other organs
What is the thoracic inlet?
The hole by which the thoracic cavity communicates with the front of the neck. Bounded by TV1, the first pair of ribs, and the upper margin of the manubrium
What is the thoracic outlet? What encloses it?
The means by which the thoracic cavity communicates with the abdomen.
Enclosed by diaphragm, TV12, ribs 12, and the edge of the lower 6 ribs + xiphisternal joint
What forms the costal margin?
The costal cartilages of 7-10. Ribs 8-10 are false ribs, 11-12 are floating ribs
What are the two joints formed by the body of the sternum?
- Manubriosternal - fibrocartilaginous joint between manubrium and sternum
- Xiphisternal - cartilaginous joint between xiphoid process and sternum
What are the two notches of the manubrium which are important?
- Suprasternal notch
2. Clavicular notch - site of sternoclavicular joint
What forms the body of the sternum?
Four fused sternebrae
What is the sternal angle?
Also called the angle of louis, it is the angle between the manubrium and sternum which is a palpable landmark for the second costal cartilage. Ribs and intercostal spaces are counted from here
How is the heart accessed for a heart surgery?
Via a median sternotomy - allows access to heart
What are the structures on a typical rib?
Head articulates with vertebral body of thoracic vertebrae.
Tubercle is a posterior projection at the junction of the neck and shaft, articulates with transverse costal facets
Subcostal groove on shaft which contains neurovascular bundle
Angle is where rib turns sharply anteriorly, right before shaft
What type of joint is the costovertebral joint and what does it articulate with?
Synovial - head of rib articulates with bodies of two adjacent vertebrae and the intervertebral disc, The tubercle articulates with transverse process of corresponding vertebrae
What are the sternocostal joints?
Synovial joints between costal cartilages 2-7 and lateral margin of sternum
What are costochondral joints?
Hyaline cartilage joints between ends of bony rib and costal cartilage
What are interchondral joints?
Synovial joints between cartilages of 7-10 at costal margin (to hold onto false ribs)
What is the function of the joints at the sternum + the costal cartilage?
Allow for respiration, add resilience to protect the sternum and ribs from more frequent fracture. With age, they may ossify with age
What is flail chest?
At least 2 fractures per rib and at least 2 ribs, making a section of chest wall no longer contribute to inspiration.
What are the external intercostal muscles and their function?
Muscles with fibers running downward and forward, from the superior rib to the rib below. They elevate during the ribs during inspiration.
They end anteriorly as the external intercostal membrane near the sternal articulation
What are the internal intercostal muscles and their function?
Muscles with fibers running upward, from the rib inferiorly to the rib superiorly. They are active in expiration
They end posteriorly as the internal intercostal membrane near the vertebral articulation
What are the innermost intercostal muscles and their function? What innervates all of these muscles?
Muscles with the same orientation as the internal intercostals, active in expiration.
Intercostal nerves innervates them all
What are the transverse thoracis muscles?
Muscles extending from posterior aspect of xiphoid process and lower sternum to costal cartilages 4-8, depressing costal cartilages
Where is the neurovascular bundle of the ribs located? Where should a needle be inserted during thoracentesis?
Between the inner and innermost intercostal muscles. The vein, artery, and nerve (VAN superior to inferior) are protected by the subcostal groove of the rib. Thus, inserting a needle above the upper border of the rib will prevent injury to vessels and nerve
What do the ventral rami of the thoracic spinal nerves become? Where do they travel?
The intercostal nerves. They are both sensory and motor, and they course around the chest wall in the neurovascular plane (subcostal groove)
What nerves supply the skin? The parietal pleura?
The anterior and lateral cutaneous branches, which are branches of the intercostal nerves. This supplies the costal and diaphragmatic parietal pleura.
What nerves supply the anterior abdominal wall including the skin, muscle, and parietal peritoneum?
Thoracic nerves 7-11 supply this area (the intercostal nerves).
What do the dorsal rami of the thoracic nerves supply?
Skin and muscle of the back
What intercostal nerves supply the skin at the level of the umbilicus? At the suprapublic level?
T10 - umbilicus
T12 - suprapubic
Where do the anterior intercostal arteries arise from?
Internal thoracic artery, off the first part of the subclavian
Where do the posterior intercostal arteries arise from? How about the first two specifically?
Thoracic aorta.
However, the first 2 PIAs arise from the supreme intercostal artery which is a branch of the costocervical trunk of subclavian
What is the fate of the internal thoracic artery?
Branches from 1st part of subclavian, descends lateral to sternal margin behind the upper 6 costal cartilages (gives off first 6 posterior intercostal arteries), before dividing into the musculophrenic and superior epigastric arteries
What is the pericardiophrenic artery?
An early branch of the internal thoracic artery, accompanying the phrenic nerve
What artery supplies the sternum, thymus gland, and overlying skin of chest wall?
Internal thoracic artery
Where do the posterior intercostal veins drain on the right and left?
Right: Azygos vein
Left: Hemiazygos vein
Where do the anterior intercostal veins drain?
Internal thoracic veins / musclophrenic veins