Anatomy Of The Heart – At A Glance

Heart is roughly conical shaped organ which is situated obliquely in the middle mediastinum
Base is directed upwards, backwards and to the right
Apex is directed downwards, forwards and to the left

Anatomy Of Heart
Fig : The Heart
Heart has….
  • Three borders
  • Three surfaces
Borders 
  1. Right border      : Right atrium with SVC and IVC
  2. Left border        : Left ventricle, auricle of left atrium
  3. Inferior border  : Right ventricle, apex of the left ventricle
Surfaces
  1. Anterior   : Mainly right atrium, auricle of left atrium, right ventricle (2/3rd), left ventricle (1/3rd)
  2. Posterior  : Posterior part of right atrium, left atrium with four pulmonary veins 
  3. Inferior    : Both ventricles, mainly left ventricle (2/3rd)
 
Base of the heart

 

Base of the heart



Chambers Of The Heart 

  1. Right atrium
  2. Right ventricle
  3. Left atrium
  4. Left ventricle



Right Atrium

  • Receives blood from….
    • SVC – Upper posterior part
    • IVC & coronary sinus – Lower part
    • Anterior cardiac vein – Anteriorly
  • Crista terminalis is a muscular ridge that separates the smooth walled posterior part from the rough walled anterior portion 
    • Smooth walled posterior part is derived from sinus venosus
    • Rough walled anterior part is derived from true fetal atrium 
      • Roughness is due to the presence of trabeculations produced by pectinate muscles
  • Crista terminalis is represented on the outer surface by sulcus terminalis as a shallow groove
  • Oval shaped depression in the interatrial septum is called as fossa ovalis
    • Site of fetal foramen ovale
  • IVC and coronary sinus is guarded by rudimentary valves 
 
Right atrium of the heart



Right Ventricle

  • Communicates right atrium through tricuspid valve
  • Communicates with the pulmonary trunk through pulmonary valve
  • Supraventricular crest is a muscular ridge that separates the inflow and outflow of the ventricles
  • Inflow tract is rough due to presence of trabecular carneae
  • Tricuspid valve has three cusps
    • Anterior, posterior, septal 
    • Atrial surface of the valve is smooth
    • Ventricular surface is attached to chordae tendinae which is attached to papillary muscles of the ventricular wall 
    • This arrangement prevent the eversion of the cusps during ventricular contraction 
  • Outflow tract is smooth walled and directed upwards towards the right guarded by pulmonary valve
  • Pulmonary valve has three semilunar cusps
  • Moderator band is a fibrous band which extends from the interventricular septum to the anterior wall of the hear 
    • Prevent overdistension of the ventricle 
    • Conveys the right branch of AV bundle 
 
Right ventricle of the heart

 

 
Left Atrium 
  • Smaller than the right atrium
  • Thick walled
  • Consist of left atrium proper and left auricle
  • Smooth walled except in the auricle where ridges are present due to underlying pectinate muscles 
  • Upper posterior part has four openings for the four pulmonary veins 
  • Shallow depression on the septal surface corresponds with fossa ovalis of right atrium
 
Left atrium of heart

 

 
Left Ventricle
  • Longer, more conical, thicker (x3)
  • Communicates with the left atrium through mitral valve 
  • Communicates with the aorta through the aortic valve
  • Mitral valve has two cusps 
    • Large anterior 
    • Small posterior 
  • Aortic valve has three semilunar cusps
    • Anterior
    • Right
    • Left posterior 
  • Above the aortic valve lies the aortic sinus
  • Mouths of the right and left coronary arteries are seen opening to the right and left posterior aortic sinus respectively  
 
Left ventricle of heart


Conduction System Of The Heart
 
It consist of….
  • SA node
  • AV node
  • Bundle of His
  • Bundle branches 
  • Purkinje fibers 
 
conduction-system-of-the-heart
Fig : Conduction System Of The Heart
 
 

Sinuatrial node is situated in the upper end of crista terminalis just right to the opening of SVC
From SA node, cardiac impulses spread throughout the atrial musculature and then reach the AV nodes
AV node lies in the interatrial septum just above the opening of the coronary sinus
Cardiac impulses are conducted to the ventricles through the AV bundle
AV bundle divides into right and left AV bundle at the junction between membranous and muscular part of interventricular septum
Right and left bundle runs under the endocardium



Blood Supply Of The Heart

Supplied by….

  1. Right coronary artery
  2. Left coronary artery
 
Arterial supply of the heart
Fig : Arterial Blood Supply Of The Heart
 
 
Right coronary artery
  • Arises from the anterior aortic sinus
  • Passes forward between pulmonary trunk and right auricle
  • Descends along the atrioventricular groove 
  • At the inferior border, it continues in the atrioventricular groove posteriorly and anastomose with the left coronary artery at the posterior interventricular groove
  • Branches of RCA
    • Marginal branch 
      • Along the lower border of the heart
    • Posterior interventricular branch
      • Runs along the inferior interventricular groove
      • Anastomose near the apex with a branch of LCA
 
Left Coronary Artery 
  • Larger than RCA
  • Arises from the left posterior aortic sinus
  • Passes behind and to the left of the pulmonary trunk 
  • Then passes along the left atrioventricular groove
  • First part of LCA is covered by the left auricle and when it reappears it is divided into two branches
  • Branches of LCA
    • Anterior interventricular branch
      • Runs along the anterior interventricular groove towards the apex
      • Anastomose with the posterior interventricular branch of RCA 
      • Supplies both the ventricles
    • Circumflex artery
      • Runs along the atrioventricular groove on the left side of the heart 
      • Anastomose with the terminal branches of RCA
 
 
Venous Drainage Of The Heart
 
Coronary sinus
  • Lies in the posterior atrioventricular groove
  • Opens in the right atrium, just left to the mouth of IVC
  • Tributaries
    • Great cardiac vein
    • Middle cardiac vein
    • Small cardiac vein 
 

Anterior cardiac veins

  • Opens directly into the right atrium
  • Up to 3 – 4 in number
  • Drains the anterior surface of the heart  
 
Venae cordis minimae
  • Small veins that drain directly into the chambers of the heart
 
Venous drainage of the heart
Fig : Venous Drainage Of The Heart
 
 
Nerve Supply Of The Heart
  • Vagus (parasympathetic cardio-inhibitor)
  • Sympathetic (cardio-accelerator) 
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Unknown
1 year ago

Simplistic.
Although you didn't talk about the vessels of the heart. The major arteries, major veins and all that.
Thank you for making this topic less broad.

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1 year ago

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