mediastinum LOs

Question 1

ID external features of the right and left lungs

Answer 1

• right
  
  • 3 lobes: superior lobe, middle lobe, inferior lobe
  • 2 fissures: oblique fissue (inferior), horizontal fissure (superior and middle)
• left:
  
  • 2 lobes: superior lobe, inferior lobe
  • 1 fissure: oblique fissure
  • also lingula

Question 2

explain pattern of branching and structural anatomy of bronchial tree

Answer 2

• trachea: rings, carina
  
  • carina is internal bifurcation
• bronchi:
  
  • primary (right and left main)
    
    • right primary is larger and more vertical, more likely to take aspirated food particles
  • secondary: lobar
  • tertiary: segmental

Question 3

medial surfaces of lungs

Answer 3

• right
  
  • superior vena cava, esophagus, azygos vein, heart
  • pulmonary artery anterior to primary bronchus
• left
  
  • aortic arch, thoracic aorta, heart, esophagus, lungula
  • pulmonary artery superior to primary bronchus

Question 4

pleural coverings of lungs including regions and recesses

Answer 4

• parietal pleura
  
  • around wall
  • parts: cervical, costal (most extensive), diaphragmatic, mediastinal
  • recesses: sites of fluid accumulation
    
    • costomediastinal (costal to mediastinal): anteromedial
    • costodiaphragmatic (costal to diaphragmatic): anteroinferior
• visceral pleura
  
  • around organ

Question 5

layers of pericardium superficial to deep

Answer 5

• fibrous pericardium
• parietal pericardium
• visceral pericardium/epicardium
• myocardium
• endocardium
• fibrous pericardium + parietal pericardium: bonded together
• parietal pericardium + visceral pericardium: serous pericardium
• visceral pericardium + myocardium + endocardium: heart

Question 6

ID surfaces features of heart

Answer 6

• anterior
  
  • right auricle on right atrium
    
    • coronary sulcus between right atrium and right ventricle
  • anterior interventricular sulcus between left and right ventricles
  • ligamentum arteriosum connection ascending aorta/arch and pulmonary trunk
• posterior
  
  • arch, pulmonary arteries
  • pulmonary veins on left atrium
  • coronary sinus between left atrium and left ventricle

Question 7

internal features of right atrium

Answer 7

• interatrial septum: wall between right and left atria
• fossa ovalis: remnant of fetal circulation
• pectinate muscle: rough, anterior wall
• crista terminalis: where pectinate muscle and interatrial septum meet
• valved orifice of inferior vena cava
• valved orifice of coronary sinus (drains heart surface)
• right atrioventricular orifice with AV valve

Question 8

internal features of right ventricle

Answer 8

• conus arteriousus
• supraventricular crest
• right AV valve (tricuspid)
• chordae tendineae
• papillary muscles: anterior, posterior, septal
• septomarginal trabeculae (near apex, septum to lateral wall)
• trabeculae carneae (rugated)
• interventricular septum (wall between ventricles)
• valve of pulmonary trunk
• pulmonary trunk

Question 9

internal features of left atrium

Answer 9

• left superior pulmonary valve
• valve of foramen ovale (like fossa ovalis)
• interatrial septum
• pectinate muscle: anterior, posterior

Question 10

internal features of left ventricle

Answer 10

• left atrioventricular valve (mitral)
• chordae tendineae
• papillary muscles
• trabeculae carneae of IV septum

Question 11

arrangement of chordae tendineae and the valves of heart

Answer 11

• valves open: blood flowing from high pressure to low pressure (atria to ventricles)
  
  • tendinous cores/valve cusp: loose
• valves closed: preventing backflow of blood from ventricles (ghigh pressure) to atria (low pressure)
  
  • chordae tendineae keep flaps from opening into atria

Question 12

cardiac auscultation sites

Answer 12

• sites located superficial to vector blood flows as it passes through each chamber/vessel
• aortic semilunar: right second intercostal space
• pulmonary semilunar: left second intercostal space
• right AV/tricuspid: left fifth intercostal space
• left AV/mitral: medial left fifth intercostal space

Question 13

blood flow through heart, including chambers and valve

Answer 13

• SVC/IVC > RA > tricuspid/right AV > RV > pulmonary valve > pulmonary trunk > pulmonary arteries > lung
• pulmonary veins > LA > mitral/left AV > LV > aortic valve >. ascending aorta > aortic arch

Question 14

conduction system of heart

Answer 14

• sinoatrial (SA) node: at apex of crista terminalis (RA)
• atrioventricular (AV) node: between RA and RV
• atrioventricular bundle (of His): between right and left AV valve
  
  • left bundle of branche (LV), right bundle of branch (RV)
  • moderator band (septomarginal trabeculae): in RV, rapid access for ventricular contraction timing

Question 15

underlying anatomy of (cardiac) referred pain

Answer 15

• pain receptors in myocardium have visceral afferent sympathetic axons to cell bodies in DRG
  
  • DRG shared with general somatic axons
• brain interprets pain from skin (left pectoral, shoulder, medial UE)

Question 16

remnants of fetal circulation

Answer 16

• ductus arteriosus (ligamentum arteriosum): pulmonary trunk to arch of aorta
• foramen ovale (fossa ovalis): right to left atrium
• lungs aren’t functional, pulmonary circulation bypassed