B3 - Pericardium, own vessels of the heart, impulse generation system of the heart, development of the heart

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 septumI)
• Bundle of His
• Tr. fasciculi
• Crus dexter
• Crus sinister
• Purkinje fibers
• Trabecula septomarginalis??

Question 4

Development of the heart

Answer 4

• When the embryo is no longer able to satisfy its nutritional requirments by diffusion alone, the vasuclar system takse over

1. Initially 1 endothelial tube
2. Cranial part of the tube will form tr. arteriosus and ventricles
3. Caudal part of the tube will form atria and sinus venosus
4. The enclosed part of the heart grows faster than the pericardial space and is forced in a flexure where the apex is directed ventrocaudally