Thorax, Heart and Lungs Flashcards
What muscles assist in inspiration?
Diaphragm
Mainly external intercostals–> expand ribs outwards
Assisted by SCM and scalenes
What law allows respiration?
Boyle’s law
What is FRC?
Amount of air left in lungs at end of passive exhalation
Opposing elastic recoil forces of lungs and chest at equilibrium
What does the thoracic wall consist of?
Skin, fascia, nerves, vessels, muscles, cartilages and bones
What are the functions of the thoracic wall?
- Protects thoracic and abdominal organs
- resists negative internal pressure generated by elastic recoil of lungs and inspiratory movmeent
- Provides attachment for and supports weight of upper limb, neck, abdomen, and back, muscles of respiration
What composes the superior thoracic aperture?
- Allows communication b/w the thoracic cavity and neck and uper limbs
- Bounded
- poteriorly by T1
- Laterally by first pair of ribs and their costal cartialges
- anteriorly by superior border of the manubrium
What composes the inferior thoracic aperture?
- Allows communication between thoracic cavity and abdomen
- Bounded
- posteriorly by the T12 vertebrae
- Posterolaterally by 11-12th pair of rib
- Anterolaterally by joined costal cartilages of 7-10 ribs
- Anteriorly by xiphisternal join
- diaphragm closes this space almost completely, separting the two cavities
What composes the thoracic skeleton?
- 12 pairs of ribs and costal cartilages
- 12 thoracic vertebrae and intervertebral disc
- Sternum
What composes the 12 ribs and costal cartilages?
- True ribs (vertebrosternal ribs) 1-7th ribs
- cartilage attached to sternum
- False ribs (vertebrochondral ribs) 8-10th ribs
- share cartilage
- Floating (free) ribs 11 & 12th ribs
- Protecting for kidney
- Costal cartialges prolong ribs anteriorly and add elasticity
- Intercostal space are names in relation to rib on superior border
- subcostal space is immediately below 12th rib
What parts form the sternum?
- Manubrium
- lies T3-T4
- Clnical landmark
- Jugular (suprasternal) notch
- Sternal angle (of louis)
- oppositie 2nd pair costal cartilages
- level of T4-T5
- Body
- T5-T9
- Xiphoid process
- T10 level
A/I of external intercostals
Action
- forced inspiration elevates ribs
Innervation
-Intercostal Nerve
“fibers go like hands in pockets”
A/I of internal intercostals?
Action
- forced respiration, interosseous part depresses ribs; interchondral part elevates ribs
Innervation
-Intercostal nerve
“muscle fibers go like arms crossed”
A/I innermost intercostal?
Action
- Forced inspiration; interosseous part depresses ribs; interchondral part elevates ribs
Innervation
-Intercostal nerve
A/I Transversus thoracic?
Action
- weakly depresses ribs
Innervation
- Intercostal nerve
A/I subcostal muscle?
Action
- act in same manner as internal intercostal (forced respiration; interosseous part depresses ribs; interchondral part elevates ribs)
Innervation
-Intercostal nerve
How is the intercostal nuroevascular bundle arranged within muscle layers of the thorax?
“VAN” (superior –> inferior)
Vein
Artery
Nerve
NV bundle in between internal and innermost intercostals
Where do the external intercostals run?
Run from vertebral column, stops short of sternum (around costal catilages)
Where do internal intercostals run?
Run from sternum, stops short of vertebral column
Where do innermost intercostals run?
Found at the most lateral parts of intercostal spaces
Where does transversus thoracis muscles run?
anterior thoracic wall
Where do subcostal muscles run?
Posterior thoracic wall
What is the diaphragm?
- Chief muscle of inspiration
- Dome shaped with left and right domes
- right dome is slightly higher than left due to presense of liver
What are the diaphragmatic apertures?
- Caval opening
- Esophageal hiatus
- Aortic hiatus
What is the caval opening?
- 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 dilation of IVC and increased blood return to heart
What is esophageal hiatus?
- Diaphragm acts as muscular sphincter for esophagus that constricts when diaphragm contracts
- transmits vagus nerve to abominal cavity
What is the aortic hiatus?
- Opening posterior to the diaphragm, therefore blood flow is not affected by respiration
- Transmits
- descending aorta,
- azygos vein and
- thoracic duct to abdominal cavity
What innervates thoracic wall?
- Thoracic segment of spinal cord supplies 12 pairs thoracic nerve
- anterior and posterior rami
- anterior rami T1-T11 form intercostal nerves’ T12 subcostal nerves
- posterior rami supply deep muscle and skin of back
- Intercostal nerves 1 and 2 pass on internal surfaces of 1st and 2nd ribs, all other along the inferior margin of costal grooves
- VAN-NAV
- Intercostal nerves 7-11 continue to supply abdominal skin and muscle
- Lateral and anterior cutaneous branches
- rami communication with sympathetic trunk to reach blood vessels, sweat glands and smooth muscles
What are the dermatomes we need to know?
T4- nipple
T6- xyphoid
T8-last rib
T10- umbilicus
What is arterial supply to thoracic wall?
- Thoracic aorta
- intercostal and subcostal branches
- Subclavian artery
- supreme intercostal arteries
- internal thoracic arteries
What composes the thoracic wall venous system?
- Anterior intercostal veins –> internal thoracic veins –> brachiocephalic veins
- Posterior intercostal veins–> azygos, hemizygos, accessory hemiazygos veins–> vena vava
- hemiazygos and accessory hemi-azygos empty into azygos vein
What is venous pathway on right side thorax?
Azygos–> SVC
What is venous pathway on left side thorax?
Hemizaygos/accessory azygous–> azygous–> SVC
What is the thoracic duct?
- Where lymph of body is transmitted
- Orginates from cisterna chyli
- Beaded appearance due to valves
- Empties into venous system near left internal jugular and left brachiocephalic vein or left subclavian vein region
What forms pleurae of lungs?
- Visceral pleura
- adherent to all surfaces of the lungs
- Parietal pleura
- lines the wall of the thoracic cavity, the mediatsinum and the diaphragm
- Continuous with each other
- pleural sac
- pleural fluid, lubricates the pleural surfaces to allow layers to slide smoothly with respiration
- Root of lung enclosed within the area of continuity
- pleural sac
- Lungs to not completely occupy the pleural cavities
- costodiaphragmatic and costomediatsinal recessess
What comprises the lungs?
Surfaces?
Borders?
- Organ of respiration
- Fissures- lobes
- Apex
- above level of first rib into root of neck
- Three surfaces
- costal surface
- mediastinal surgace
- diaphragmatic surface
- Three borders
- anterior border
- inferior border
- posterior border
Features of right side of lung?
- Horizontal and oblique fissues
- 3 lobes
- superior, middle and inferior lobe
- Larger and heavier, but shorter and wider than left lung, due to right dome of diaphragm being higher
What is the arrangement of root of right lung?
- Hilum- joins lung to heart and trachea
- pulmonary artery (deoxygenated) anterior, superior
- 2 pulmonary veins (oxygenated)- inferior
- Bronchus/bronchi- superior posterior
Characteristics of left lung?
- Oblique fissure
- 2 lobes
- superior and inferior
- Cardiac notch and cardiac impression
- lingula
What is organization of root of left lung?
- Hilum - joins lung to heart and trachea
- Pulmonary artery (deoxygenated)= most superior
- 2 pulmonary veins- anterior inferior
- Bronchus/bronchi- posterior
Where is the carina?
T4
Organization of mainstem bronchi?
- Right mainstem is 2.5 cm long with angle 25 degree and wider than left
- Left mainstem is 5 cm long with angle of 45 degrees
Organization of bronchial tree?
- Carina
- mainstem bronchi
- lobar bronchi (secondary)
- Right has 3
- Left has 2
- segmental bronchi (tertiary)
- 20-25 generation of branches that end in terminal bronchioles
- respiratory bronchioles (beginning of gas exchange)
- alveolar ducts
- alveolar sacs (basic unit of gas exchange)
What composes the pulmonary trunk?
- Pulmonary artery (1 to each lung)
- Deoxygenated blood
- Enters hilum
- Lobar and segmental arteries
- •Pulmonary veins (2 to each lung)
- Oxygenated blood
- Empty into left atrium
What provides the vasculature of the lungs?
- Bronchial arteries
- Blood to structures comprising the roots of the lungs, supporting tissues of the lungs and visceral pleura
- Branch of the aorta; run posterior to main bronchi
- Blood to main bronchi to respiratory bronchioles
- Bronchial veins
- Drain only part of the blood supplied by bronchial arteries
- Right drains into the azygos vein and left into accessory hemi-azygos vein
- Remainder of blood is drained by pulmonary veins (oxygenated blood) into left atrium
- Physiologic shunt
What is the pulmonary plexus?
- Pulmonary plexus
- Anterior and posterior to roots of the lung
- Parasympathetic fibers
- Vagus (CN X)
- Sympathetic fibers
- Sympathetic trunks
What is the SNS/PSNS innervation of tracheobronchial tree?
- Parasympathetic- CN X (main body of vagus provides innervation carina to alveoli. above carina is recurrent laryngeal nerve)
- Motor to smooth muscle- bronchoconstrictor
- Inhibitory to pulmonary vessels- vasodilator
- Secretory to glands bronchial tree- secretomotor
- Sympathetic- paravertebral sympathetic ganglia
- Inhibitory to bronchial smooth muscle- bronchodilator
- Motor to pulmonary vessels- vasoconstrictor
- Inhibitory to alveolar glands of bronchial tree
What composes the mediastinum?
- Occupied by the viscera between the pulmonary cavities
- Contains all of the thoracic viscera, except the lungs
- Superior mediastinum
- Inferior mediastinum
- Anterior mediastinum
- Lymph nodes, fat and connective tissue
- Middle mediastinum
- Posterior mediastinum
- Anterior mediastinum
What is located in superior mediatsinum?
Runs from angle of lewis, up in chest cavity
- Thymus
- Great vessels (brachiocephalic, sup part SVC, pulmonary trunk, roots PA, arch of aorta with branches)
- Ligamentum arteriosum
- Vagus nerves
- Relation to ligamentum arteriosum
- Phrenic nerves
- Cardiac plexus of nerves
- Trachea
- Esophagus
- Thoracic duct
What are the great vessels contained in the superior mediastinum?
- Brachiocephalic veins- receives lymph from the body, left twice as long as right
- Central lines! possible to cross left–> right
- Superior part superior vena cava
- Bifurcation of the pulmonary trunk
- Roots of the pulmonary arteries
- Arch of the aorta and major branches
- Brachiocephalic trunk
- Left common carotid
- Left subclavian artery
What composes the posterior mediastinum?
- Thoracic duct
- Posterior mediastinal lymph nodes
- Azygos, hemi-azygos, and accessory hemi-azygos veins
- Thoracic sympathetic trunks
- Thoracic splanchnic nerves
- Thoracic aorta
- Surrounded by thoracic aortic sympathetic plexus
- Esophagus
- Esophageal plexus
- Vagus nerve
What is located inside the middle mediastinum?
- Pericardium
- Heart
- Ascending aorta
- Pulmonary trunk
- Superior vena cava
- Arch of the azygos vein
- Main bronchi
What is the pericardium?
- Double-walled membrane
- Encloses the heart and roots of the great vessels
- Outermost layer is the parietal layer
- Reflected onto the heart and great vessels
- Innermost layer is the visceral layer
- Comprises the epicardium (external layer of the heart wall)
- Pericardial cavity
- Contains serous fluid
- Frictionless movement of the heart
What is vasculature to pericardium?
•Pericardiacophrenic artery (branch of the internal thoracic artery) and pericardiacophrenic veins
What are the 3 layes of tissue of heart?
- Epicardium
- Thin external layer formed by the visceral layer of the pericardium
- Myocardium
- Thick, middle layer composed of cardiac muscle
- Endocardium
- Thin internal layer that lines the heart and covers the valves
The heart is a ___ ___
Double pump
- Right side receives poorly oxygenated blood from the SVC/IVC and pumps blood to the lungs via pulmonary trunk
- Left side receives highly oxygenated blood from the lungs via pulmonary veins and pumps to the body via aorta
What is the heart’s orientation in the chest?
- Apex
- Anteriorly and to the left
- Inferolateral part of the left ventricle
- 5th intercostal space, 9 cm from median plane
- Base
- Posterior aspect
- Left atrium
- T6-T9
- Anterior surface
- Right ventricle
- Diaphragmatic (inferior) surface
- Left ventricle and part of right ventricle
- Left pulmonary surface
- Left ventricle, cardiac impression of left lung
- Right pulmonary surface
- Mainly by right atrium
Where is the apex of the heart? What part of heart does that consist of?
- Anteriorly and to the left
- Inferolateral part of the left ventricle
- 5th intercostal space, 9 cm from median plane
Where does base of heart sit? What does it consist of?
- Posterior aspect
- Left atrium
- T6-T9
What’s along the anterior surface ofthe heart?
Right ventricle
What’s along the diaphragmatic surface of the heart?
Left ventricle and part of RV
What’s along left pulmonary surface?
Left ventricle, cardiac impression of left lung
What rests along right pulmonary surface?
Mainly right atrium
What is the right auricle?
- Closet of heart
- muscular pouch can expand to increase capacity in right atrium
- overlaps ascending aorta
Features in RA?
- Right auricle
- coronary sinus
- sinus venarum
- crista terminalis
- perctinate muscle
- interartrial septum
What is the coronary sinus?
Receives blood from coronary veins (in right atrium)
What is the sinus venarum?
Located in right atrium
- Smooth area
- SVC level 3rd intercostal
- IVC level 5th intercostal
- coronary sinus between right AV orifice and IVC orifice
What is the crista terminalis?
Located in right atrium
- ridge of muscle connected to sinus venarum
What are the pectinate muscles?
Located in right atrium
- forms muscular wall
What is the interatrial septum?
Separates atrium
Oval fossa (fossa ovalis), remants of fetal foramen ovale
What is the tricuspid valve?
- Right atrioventricular (AV) valve
- Guards right AV orifice (4th-5th intercostal spaces)
- Three cusps (tricuspid plays TAPS)
- Anterior, septal and posterior
- Chordae tendineae attach to anterior, septal and posterior papillary muscles
- Prevent valve from prolapsing during ventricular contraction (systole)
- Papillary muscles contract slightly before ventricle to draw cusps together
- Normal valve opening: 4-6 cm2
What is the conus arteriosus?
On right ventricle
Leads to pulmonary trunk
Features of RV?
- Conus arteriosus
- trabeculae carnae
- papillary muscles
- intraventricular septum
- setpmarginal trabecula (moderator band)
What is the trabeculae carnae?
Inside right ventricle
Irregular muscular elevations (inside ventricle)
What are papillary muscles?
Connect to chordae tendinae
What is the intraventricular septum?
Separates right and left ventricle
bulges into right ventricle due to increased pressure in left
What is the septomarginal trabecula?
- (moderator band)
- Carries part of the right bundle branches of the AV bundle to the anterior papillary muscle
- Facilitates conduction time and allows for coordinated contraction of the anterior papillary muscle
Characteristics of pulmonary valve?
- Semilunar valve
- Apex of the conus arteriosus (3rd costal cartilage)
- Three cusps
- Anterior, right and left (PA go together like LR)
- Pulmonary sinus just superior to valve, start of the pulmonary trunk
- Blood prevents cusps from reopening during diastole
- Normal valve opening: 2 cm2
Characteristics of left atrium?
- Receives well oxygenated blood from pulmonary system
- Left auricle
- Overlaps pulmonary trunk
- Contains pectinate muscles
- Four valve-less pulmonary veins
- Right and left superior and inferior
- Posterior wall
- Slightly thicker wall than right atrium
- Left AV orifice
What is the left auricle?
In left atrium
- Overlaps pulmonary trunk
- Contains pectinate muscles
Characteristics of mitral valve?
- Left atrioventricular (AV) valve; Bicuspid valve
- Guards left AV orifice (4th costal cartilage)
- Two cusps
- Anterior and posterior (remember MAP)
- Chordae tendineae attach to anterior and posterior papillary muscles
- Prevent valve from prolapsing during ventricular contraction (systole)
- Papillary muscles contract slightly before ventricle to draw cusps together
- Normal valve opening: 4-6 cm2
- •
What does the left ventricle consist of?
Walls are 2-3 times thicker than right ventricle
- Trabeculae carneae
- Finer but more numerous than right ventricle
- Anterior and posterior papillary muscles
- Larger than those in right ventricle
- Aortic vestibule
- Smooth walled area leading to aortic orifice
- Aortic orifice
- Outflow to ascending aorta
- Contains aortic valve
Characteristics of aortic valve?
- Semilunar valve
- Apex of the aortic vestibule
- Three cusps
- Left, right and posterior
- Aortic sinus just superior to the cusps, start of the ascending aorta
- Right aortic sinus contains the opening of the right coronary artery
- Left aortic sinus contains the opening of the left coronary artery
- Posterior aortic sinus does not contain a coronary artery
- Normal valve opening: 2.5- 4.5 cm2
At what point do you have aortic stenosis?
<1.8 cm2 valve opening
What valves are open in diastole
- Tricuspid and mitral
What valves are open in systole
aortic and pulmonic
What composes 1st heart sound?
First heart sound, S1
- Closure of the AV valves
- Systole
- Tricuspid valve
- Near left sternal border in 5th intercostal space
- Mitral valve
- apex of heart in 5th intercostal space, midclavicular line
What composes 2nd heart sound?
- Closure of semilunar valves
- Early diastole
- Aortic valve
- 2nd intercostal space, right of sternal border
- Pulmonary valve
- 2nd intercostal space, left of sternal border
What supplies blood to heart? Where do they arise from? Go to?
- Coronary arteries
- Supply myocardium and epicardium
- endocardium supplied by blood in chambers of heart
- Embedded in fat and just deep to epicardium
- arise from right and left aortic sinuses, proximal to ascending aorta, just superior to aortic valve
What does a right dominate system mean? Left dominate?
means RCA supplies posterior interventricular branch.
Left dominate means LCA supplies blood to posterior interventricular branch.
Course of the RCA? What does it branch off to?
- Arises from right aortic sinus
- Runs along coronary sulcus
- SA nodal branch
- supplies SA node
- Right marginal branch
- right border of heart
- Av nodal branch
- crux of heart (junction of septa and walls of four chambers)
- av node
- Posterior interventricular branch
- left and right ventricles
- interventricular septum
What does RCA typically supply in right dominate system?
- RA
- Most RV
- Part LV
- Part IV septum (posterior third)
- SA node (60% people)
- AV node (80% people)
Where does LCA come off from?
What does it divide into?
- Comes off left aortic sinus
- Runs along coronary sinus
- Divdes into:
- anterior interventricular branch (LAD)
- Interventricular setpum
- anastomoses with posterior IV branch of RCA
- Circumflex branch
- left posterior ventricle
- left marginal artery
- left ventricle
What does LCA supply?
Typically supplies
- Left atrium
- Most of the left ventricle
- Part of the right ventricle
- Most of the IV septum (anterior two-thirds)
- AV bundle of conducting tissue
- SA node in 40% of people
What makes venous drainage of heart?
- Great cardiac vein
- middle cardiac vein
- small caridac vein
- coroanry sinus
- anterior cardiac veins empty into RA (or coronary sinus)
What does the great cardiac vein follow? Empty into?
Follows LAD and circumflex
Empties into coronary sinus
What does the middle cardiac vein vollow? Empy into?
Close proximity to posterior itnerventricular branch
empty into coronary sinus
What does small cardiac vein follow?Empty into?
Follows RCA
Empty into coronary sinus
Where does coronary sinus empty into?
right atrium
What is conduction pathway through heart?
- Sinu-atrial (SA) node
- Nodal tissue that initiates and regulates heartbeat; 60-100 bpm
- Deep to epicardium, junction of SVC and right atrium
- Internodal tracts to depolarize atria
- Atrioventricular (AV) node
- Smaller collection of nodal tissue
- Directs SA nodal signal to septum and initiates and regulates heartbeat (if SA node fails); 40-60 bpm
- Interatrial septum near the opening of the coronary sinus
- Atrioventricular bundle of HIS
- Distributes signal to ventricles
- Right and left bundle branches
- Purkinje fibers (subendocardial branches)
- Nodal tissue; if SA/AV nodes fail to fire will initiate heartbeat; 20-40 bpm
What provides sympathetic innervation to heart?
- Superficial and deep cardiac plexuses
- around bifurcation carina
- Presynaptic fibers with cell bodies in the intermediolateral cell columns of the superior 5-6 thoracic segments of spinal cord
- T1-T5 typically
- Postsynaptic fibers with cell bodies in the cervical and superior thoracic paravertebral ganglia of the sympathetic trunks
- Postsynaptic fibers end in the SA and AV nodes and close to coronary arteries
- Increases heart rate and force of contraction
- Dilation of coronary arteries by inhibiting their constriction
What is parasympathetic innervation of heart?
- Superficial and deep cardiac plexuses
- Parasympathetic
- Presynaptic fibers of the vagus nerve (CN X)
- Postsynaptic cell bodies located near SA and AV nodes and along coronary arteries
- Slows heart rate and reduces force of contraction
- Constricts coronary arteries
What causes referred chest pain?
Cardiac pain is carried on sympathetic nerve fibers back to spinal cord. These travel in DRG along with sensory from T3-T6 dermatomes on arm. The brain can not differentiate where the pain is coming from, so you also experience arm pain with chest pain.
What is the bezold-jarisch reflex?
Stimulus: Profound hypovolemia of left ventricle and myocardial ischemia
Reflex result:Bradycardia, hypotension and coronary vasodilation
Bainbridge Reflex?
Stimulus: A full heart and venous congestion
Result: Increased heart rate
Chemoreceptor reflex?
Stimuli: hypoxia and hypercarbia
Reflex result: increase MV and sympathetic tone
Baroreceptor Reflex?
Stimuli: Acute decreased blood pressure (or acute increase blood pressure)
Reflex result: Increased heart rate, increased contractility and increased SVR (opposite for increased blood pressure)
What does the SA nodal branch perfuse?
SA node
What does the right maginal branch perfuse in the heart?
right border of the heart
What does the AV nodal branch of the heart perfuse?
- AV node
- crux of the heart (junction of septa and walls of the four chambers)
What does the posterior interventricular branch supply in the heart?
Left and Right ventricles
Interventricular septum
What does the anterior interventricular branch (left anterior descending) supply?
- left and right ventircles
- interventricular septum
- anastomoses with posterior IV branch of RCA
What does the circumflex branch supply?
left posterior ventricle
What does the left marginal artery supply?
left ventricle
