Thorax, Heart, and Lungs Flashcards
What makes up the thoracic wall?
- skin
- fascia
- nerves
- vessels
- muscles
- cartilages
- bones
What are the functions of the thoracic wall?
- Protects thoracic and abdominal organs
- resists the negative internal pressures caused by the elastic recoil of the lungs and inspiratory movements
- provides attachment for and supports the weight of the upper limbs, neck, abdomen, back, and muscles of respiration
Superior thoracic aperture
What does it do?
Where is it located?
- allows communication between the thoracic cavity and the neck and upper limbs
- Bounded:
- posteriorly by T1
- Laterally by the first pair of ribs and their costal cartilages
- anteriorly by the superior border of the madubrium
Inferior thoracic aperture
What does it do?
What is it bounded by?
- allows communication between the thoracic cavity and the abdomen
- Bounded:
- posteriorly by the T12 vertebra
- posterolaterally by the 11-12th pair of ribs
- anterolaterally by the joined costal cartilages of 7-10 ribs
- Anteriorly by the xiphisternal joint
- ***Diaphragm closes this space almost completely separating the two cavities
What makes up the Thoracic skeleton?
12 pairs of ribs and costal cartilages
Which ribs are the true ribs?
Vertebrosternal ribs- 1st-7th
Which ribs are the false ribs?
Vertebrochondral ribs
8th-10th ribs
Which ribs are the floating ribs?
Free ribs
11-12th ribs
What do the costal cartilages do?
prolong the ribs anteriorly and add elasticity
How are the intercostal spaces named?
In relation to the rib on the superior border
**subcostal space is immediately below the 12th rib
Sternum
and its clinical landmarks
- Manubrium- T3-T4
- Clinical landmarks:
- Jugular (suprasternal) notch
- Sternal angle (of Louis)
- Opposite 2nd pair of costal cartilages
- Level of T4-T5
- Clinical landmarks:
- Body
- T5-T9
- Xyphoid process
- T-10
What are the muscles of respiration and what nerve innervates them?
(5)
- Muscles:
- External intercostal
- internal intercostal
- Innermost intercostal
- transversus thoracis
- subcostal
- All innervated by the intercostal nerve
External intercostal
innervation
action
- Intercostal nerve
- elevates ribs on forced inspiration
Internal intercostal
Innervation
action
- intercostal nerve
- On forced inspiration, the interosseous part depresses ribs and the interchondral part elevates ribs
Innermost intercostal
innervation
action
- intercostal nerve
- on forced inspiration: interosseous part depresses ribs; interchondral part elevates ribs
Transversus thoracis
innervation
action
- intercostal nerve
- weakly depresses ribs
Subcostal
innervation
action
- intercostal nerve
- On forced inspiration: interosseous part depresses ribs; interchondral part elevates ribs
Between which muscles does the intercostal neurovascular bundle lie?
Internal intercostal and innermost intercostal
What are the diaphragmatic apertures?
(3)
- Caval opening
- esophageal hiatus
- Aortic hiatus
Caval opening
location
function
- located in central tendon
- Allows IVC and terminal branches of phrenic nerve to pass into abdominal cavity
- During inspiration, diaphragm contracts causing this opening to widen which allows for dilation of the IVC and increased blood return to the heart
Esophageal hiatus
location
function
- In the lumbar part of diaphragm
- Diaphragm acts as a muscular sphincter for the esophagus that constricts when diaphragm contracts
- transmits the vagus nerve to abdominal cavity
Aortic Hiatus
location
function
- Opening posterior to the diaphragm therefore blood flow is not affected by respiration
- Transmits the descending aorta, azygos vein and thoracic duct to abdominal cavity
What is unique about the 1st and 2nd intercostal nerves compared to the others?
- Intercostal nerves 1 and 2 pass on the internal surfaces of the 1st and 2nd ribs
- All others run along the inferior margin of the costal grooves
Which intercostal nerves continue to supply abdominal skin and muscles?
7th-11th
Which arteries to the throacic wall come off the subclavian artery?
supreme intercostal arteries
internal thoracic arteries
Which arteries come off the thoracic aorta?
Intercostal and subcostal branches
Where do the anterior intercostal veins empty?
Internal thoracic vein to brachiocephalic veins
Where do the posterior intercostal veins empty?
hemi-azygos (lower part) or accessory hemi-azygos (upper part) veins to the azygos vein which brings blood to the vena cava
Lymphatic thoracic duct
Origination
where does it empty?
- originates from the cisterna chyli
- empties into the venous system near the left internal jugular and left brachiocephalic vein
Visceral pleura vs Parietal pleura
- Visceral pleura adheres to all surfaces of the lungs
- Parietal pleura lines the wall of the thoracic cavity, the mediastinum, and the diaphragm
- **pleural fluid lubricates the pleural surfaces to allow the layers to slide smoothly with respiration
What are the names of the pleural cavities without lung in them?
Costodiaphragmatic and costomediastinal recesses
Lungs
Apex
three surfaces
thress borders
- Apex- goes above the level of the first rib and into the root of the neck
- three surfaces
- costal surface
- mediastinal surface
- diaphragmatic surface
- Three borders
- anterior border
- inferior border
- posterior border
What is associated with the Right lung?
- Hilum
- Pulmonary artery
- 2 pulmonary veins
- bronchus/bronchi
- vena cava
- azygos vein
- esophagus
What is associated with the Left lung?
- Root of the lung
- hilum
- pulmonary artery
- 2 pulmonary veins
- bronchus/bronchi
- aorta
- esophagus
- Lingula
- cardiac notch
Level of Carina
T4
Mainstem bronchi
- Right mainstem bronchi is 2.5 cm long with 25 degree angle
- Left mainstem bronchi is 5 cm long and 45 degree angle
Lobar bronchi Left Vs right
Left has 2
Right has 3
How many generations of branches?
20-25
Where does gas exchange begin?
Respiratory bronchioles
What innervates the tracheobronchial tree?
- Pulmonary plexus
- anterior and posterior to roots of the lung
- Parasympathetic fibers- CN X
- Sympathetic fibers- sympathetic trunks
Parasympathetic innervation of the tracheobronchiole tree does what?
- motor to smooth muscle- bronchoconstrictor
- inhibitory to pulmonary vessels- vasodilator
- secretor to glands bronchial tree- secretomotor
Sympathetic innervation of tracheobronchiole tree does what?
- from paravertebral sympathetic ganglia
- inhibitory to bronchial smooth muscle- bronchodilator
- Motor to pulmonary vessels- vasoconstrictor
- inhibitory to alveolar glands of bronchial tree
What is in the Mediastinum and what are the different parts?
- contains all of the thoracic viscera, except the lungs
- parts
- superior mediastinum
- inferior mediastinum
- anterior- lymph nodes, fat, and connective tissue
- middle
- posterior
What is in the superior mediastinum?
(8)
- thymus
- great vessels
- brachiocephalic veins (L twice as long as R)
- Superior part of SVC
- Bifurcation of pulmonary trunk
- roots of pulm arteries
- arch of the aorta and major branches
- Ligamentum arteriosum- remnant of fetal ductus arteriosus
- vagus and phrenic nerves
- Cardiac plexus
- trachea
- esophagus
- thoracic duct
What is in the posterior mediastinum?
(8)
- thoracic duct
- posterior mediastinal lymph nodes
- azygos, hemi-azygos, and accessory hemi azygos veins
- thoracic sumpathetic trunks
- thoracic splenchnic nerves
- thoracic aorta/thoracic aortic sympathetic plexus
- esophagus/esophageal plexus
- vagus nerve
What is in the middle mediastinum?
(7)
- pericardium
- heart
- ascending aorta
- pulmonary trunk
- superior vena cava
- arch of the azygos vein
- main bronchi
Pericardium
arery
vein
innervation
- pericardiacophrenic artery (branch of internal thoracic artery)
- pericardiocophrenic veins
- Phrenic nerve for sensory
- sympathetic trunks- vasomotor
Where is pericardium sensory from the phrenic nerve referred to?
C3-C5 dermatomes
What are the three layers of the heart?
- epicardium
- thin external layer formed by the visceral layer of the pericardium
- myocardium
- think middle layer composed of cardiac muscles
- endocardium
- thin internal layer that lines the heart and covers the valves
Location of Apex and Base of heart
Apex: 5th intercostal space, 9 cm from median plane
Base: T6-T9
