B4 - Pericardium, the heart’s own vessels, impulse generating and conducting systems

Question 1

Pericardium

Answer 1

• Surrounds the:
  
  • Heart
  • Initial portions of the aorta
  • Truncus pulmonalis
  • Terminal segment of the vv. cavae and vv. pulmonales
• Liquor pericardi moistens the opposing surfaces of the heart and pericardium
  
  • ​Thin film of serous fluid
• In mediastinum
• Consists of 3 layers:
  
  • Pleura pericardia (covers)
  • Pericardium fibrosum (outer fibrous part)
  • Pericardium serosum
    
    • ​Lamina parietalis
    • Lamina visceralis
• Dorsally the pericardium fibrosum continues onto the tunica externa of the blood vessels. Thus connected to the fascia endothoracica, which forms suspension of heart to vertebral column
• Ca, sus: Lig. phrenicopericardium (pericardium fibrosum → diaphragma)
• Eq: Lig. sternopericardium (pericardium fibrosum → sternum)
• Sinus transversus pericardii (Pericardial space between aorta, pulmonary trunk and atrial wall)
• Sinus obliquus pericardii (Pouch between left and right pulmonary veins and left atrium)​

Question 2

Own vessels of the heart

Answer 2

• A. coronarius sinistrus
  
  • ​Arises from aorta
  • Reaches sulcus coronarius by passing between left auricle and pulmonary trunk
  • R. paraconalis (left branch, follows sulcus paraconalis)
  • R. circumflexus (right branch, follows sulcus coronarius)
    
    • ​R. interventricularis subsinosus
• A. coronarius dextrus
  
  • Arises from aorta
  • Ca, ru: (left type of coronary distribution)
    
    • R. circumflexus → coronary groove to atrial surface → does not go down to subsinosal groove
  • ​Eq, sus: (right type of coronary distribution)
    
    • R. circumflexus → coronary groove to atrial surface → go down to subsinosal groove as r. interventricularis subsinosus
• Blood is returned into the heart mainly by v. cardiaca major that opens into right atrium via coronary sinus
• V. cordis
  
  • ​Blood from the heart empties into the right atrium vis sinus coronarius
  • V. cordia magna (left surface → sinus coronarius)
  • V. obliqua atrii sinistra
  • V. cordis media (right surface → sinus coronarius)
  • Vv. cordis parvae (near the coronary groove of right ventricle)
  • Vv. cordis minimae

Question 3

Impulse generation system of the heart

Answer 3

• Nodus sinuatrialis (sulcus terminalis of right atrium and opening of v. cava cranialis)
• Nodus atrioventricularis (atrial septum)
• Bundle of His
• Tr. fasciculi
• Crus dexter
• Crus sinister
• Purkinje fibers
• Trabecula septomarginalis??