Indmedica Home | About Indmedica | Medical Jobs | Advertise On Indmedica
Search Indmedica Web
Indmedica - India's premier medical portal

Journal of the Anatomical Society of India

A Study On Principal Branches of Coronary Arteries In Humans

Author(s): Kalpana, R.

Vol. 52, No. 2 (2003-07 - 2003-12)

Department of Anatomy, Thanjavur Medical College, Thanjavur, INDIA


Coronary artery disease is one of the major causes of death in developing countries. The increasing use of diagnostic and therapeutic interventional procedures necessitates that a sound, basic knowledge of the coronary artery pattern is essential. With this aim, the normal patterns of coronary arteries is studied, with reference to the predominance, branching patterns and variations. A hundred specimens were collected from the Forensic Medicine and Anatomy Departments and studied. Of the various methods available, manual dissection of coronary arteries was followed.

90% of the ostia of Right coronary and 80% of the ostia of Left coronary arteries were below the Sino-tubular Junction (STJ). Both the proximal and distal segments of Right coronary artery were present in 89%. The Third coronary artery was present in 24%. Left coronary artery showed Bifurcation in 47%, Trifurcation in 40%, Quadrifurcation in 11%, Pentafurcation in 1% and only one branch in 1%. In one specimen, apart from the Right coronary artery, an anomalous artery arose by a separate ostium from the Right aortic sinus and passed towards the left in the course of circumflex branch. There was a Right Dominance in 89% and left Dominance in 11% of the specimens studied. An intimate knowledge of the anatomy of coronary arteries, the 'Crown' of the heart, is a self evident prerequisite for a complete understanding of the coronary artery disease or for more intelligent planning of surgery. Harvey realised it earlier than any anatomist that, “Structure is a real guide to function. No physiological theory can be true unless it gives a complete and final explanation of all points of structure.” The present study on the principal branches of coronary arteries and their variations whould be of use to the cardiologists and interventional radiologists to predefine the abnormalities by invasive or non-invasive studies.

Key words: Right coronary Artery (RCA), Left coronary artery (LCA), Third coronary artery, AV nodal Artery (AVNA), SA nodal artery (SANA), Left circumflex artery, Left anterior Descending Artery (LAD), Sino Tubular Junction (STJ), Posterior Interventricular Artery (PIVA).


More progress has been made in the last few decades than in all foregoing medical history in the management of cardio-vascular diseases. One incorrectable lesion after another has nowadays beome amenable to correction, as more and more newer surgical and interventional techniques are being introduced.

Knowledge of the normal and variant anatomy and anomalies of coronary circulation is an increasingly vital component in the management of congenital and acquired heart diseases. Congential, inflammatory, metabolic and degenerative diseases may involve the coronary circulation and increasingly complex cardiac surgical repairs demand enhanced understanding of the basic anatomy to improve the operative outcomes.

The incidence of congential coronary artery anomalies is 5-6% (Mongiardo, 1991). By definition, the term anomalous or abnormal is used to define any variant form observed in less than 1% of the general population (Bekedam & Vligen, 1999). The recent introduction of selective coronary arteriography that provides an accurate localisation of the anatomical variations and underlying pathology, the advances made in coronary arterial bypass surgeries and modern methods of mycocardial revascularisation makes it imperative that a thorough, sound and complete knowledge of the normal and variant anatomy of coronary artery and circulation is required, which led to this study.

Materials and Methods:

The 100 specimens for this study were obtained from the Anatomy and Forensic Medicine departments. The specimens were collected without any age, sex, socio-economic status, religion, educational or pathological basis. The specimens thus collected were serially numbered 1 to 100. These were fixed in 10% Formalin solution. The visceral pericardium was removed to expose the coronary arteries. The Right and Left coronary arteries were dissected out, noting down their branching pattern and variations if any, at the subepicardial level.


The Right coronary ostium was present in all the specimens in the Right anterior aortic sinus. The ostium was below sino tubular junction (STJ) in 90%, at STJ in 9% and above STJ in 1% of specimens. The RCA was divided by the crux into proximal and distal segments. Both the segments were present in 89%. The proximal segment was further subdivided into First segment (origin to inferior border) and Second segment (inferior border to crux) (Williams et al, 1995).

The SA nodal arterty (SANA) was found originating in 56% of specimens from RCA, in 35% from LCA, and in 8% from both. In one specimen, SANA arose directly from the aorta, by a separate ostium, near the ostium of RCA and coursed the routine descriptive route.

The Right conus artery and the Marginal artery were present in all the specimens. The Right conus artery arising separately from the anterior aortic sinus is the Third coronary artery (Schlesinger & Zoll, 1949). The Third coronary artery was present in 24% of the specimens studied. The A.V. Nodal arterty (AVNA) arises commonly from the inverted loop said to characterise the RCA at the crux where the Posterior Interventricular artery (PIVA) arises. The AVNA arose from the RCA in 82% and from LCA in 18% of the specimens.

The PIVA arose from RCA in 89% and from LCA in 11% of the specimens. Parallel branches to PIVA were noted in 6% of the specimens. (Table 1).

Table-1 Termination of Posterior Interventricular Artery:

NO. (%) NO. (%)
Provided By
I Right coronary Artery:
¼ Way down PIVS 2 (2) 9 (9)
½ Way down PIVS 27 (25) 46 (46)
¾ Way down PIVS 39 (37) 26 (26)
At Apex 28 (26) 8 (8)
Total 96 (90) 89 (89)
II Left coronary Artery:
¼ Way down PIVS - - - -
½ Way down PIVS 5 (5) 7 (7)
¾ Way down PIVS 3 (3) 4 (4)
At Apex 2 (2) - -
Total 10 (10) 11 (11)
Grand Total 106 (100) 100 (100)

Ab: PIVS -Posterior interventricular Septum.

Table-1 describes the point of termination of the PIVA, provided by both the RCA and LCA and compares our study with that of James, 1961.

The RCA terminated at 1-3 cms beyond crux in 76%, reached upto the left border in 8%, terminated at the crux in 6%, at right margin in 7% and between right marigin and crux in 3% of the specimens.

The ostium for LCA was found in the left posterior aortic sinus in all the specimens. The ostium was below the level of STJ in 80% and at STJ level in 20%. The length of the main trunk of LCA was ranging from a minimum of 2mm to a maximum of 20mm with 88% of the specimens having a length between 6 and 15mms.

The main trunk of LCA bifurcated in 47%, trifurcated in 40% and quadrifurcated in 11% of specimens. One specimen showed Pentafurcation. (Fig.1) In another specimen, the main trunk of LCA did not divide, but continued as LAD and the circumflex branch had an anomalous origin from Right anterior aortic sinus.

The LAD branch crossed over the apex to reach upto 2-5 cms up the posterior inter-ventricular sulcus in 80%, upto the anterior apex in 8% and upto the posterior apex in 12% of the specimens.

The circumflex branch terminated between the obtuse margin and the crux in 67%, before obtuse margin in 3%, at obtuse margin in 13%, at crux in 6% and beyond crux in 11%. Of these, in one specimen, the circumflex branch was anomalous and found to be arising from the right anterior aortic sinus apart from the RCA and passed towards the left between aorta and left atrium and terminated between the obtuse margin and the crux. In this specimen, however, the LCA arose from the left posterior aortic sinus, the left conus artery was absent and the left anterior descending branch was a direct continuation of the main trunk & passed through the anterior inter-ventricular sulcus and terminated 2-5cms up the PIVS (Fig-2)

The Right coronary artery was the dominant artery in 89% and the Left in 11% of the specimens. (Fig.3)


Branches of coronary arteries may vary in origin, distribution, number and size. The name and nature of a coronary artery or a branch is defined by that vessel's distal vascularization pattern or territory, rather than by its origin.

The location, level and size of the ostium is very important in the successful performance of a coronary angiogram (Engel & Torres, 1975). Difficulty in manipulating the catheter tips will be considerably higher in patients with the ostium above the level of STJ. (Taylor & Thorne, 2000). The Right and left coronary ostia were present at the anterior aortic and left posterior aortic sinus respectively in all the specimens studied and there were no variations in the location of the ostia.

The first and highest branch of the proximal segment of RCA, arises in 36% of the cases from a separate ostium (Third Coronary Artery), in the Right aortic sinus of valsalva (Williams et al 1995). In our study, the third coronary artery was present in 24% of the specimens studied.

The second branch of first segment of RCA, the SANA, according to Uemura, (1999) arises from RCA in more that 60% and from LCA in less than 44% of the specimens. The distribution of SA Nodal arteries allows to understand the possible ischaemic etiology of the Sinusal nodal syndrome and permits the surgeon, a safe approach to the cardiac diseases (Caetano & Lopes, 1995). (Table. II)

Table-II: Sino-Atrial Nodal Artery (SANA)

Source Of SANA Baroldi & Scomazzoni (1956) James (1961) Caetano & Lopes (1995) Present Study
No. (%) No. (%) No. (%) No. (%)
RCA 51 (51) 57 (54) 58 (58) 56 (56)
LCA 41 (41) 45 (42) 42 (42) 35 (35)
Both 8 (8) 4 (4) 0 (0) 8 (8)
Directly from aorta - - - - - - 1 (1)
Total 100 (100) 106 (100) 100 (100) 100 (100)

Table-II compares the source of SANA in our study with that of the studies of Baroldi and Scomazzoni, 1956; James 1961; and Caetano & Lopes, 1995.

James (1961) had noted PIVA as a terminal branch of RCA in 80% of the cases. In our study, PIVA arises from RCA in 89% of the specimens.

In about 87% of the specimens in our study, the main trunk of LCA showed either a bifurcation or trifurcation (Table. III)

Table-III: Divisions of Main Trunk of Left Coronary Artery (In percentage)

Branches Baptista,
Present study
One Branch - - 1
Bifurcation 54.7 60 47
Trifurcation 38.7 38.18 40
Quadrifurcation 6.7 - 11
Pentafurcation - - 1

Table-III compares the divisions of main trunk of LCA with the studies of Baptista, (1991) and Cavalcanti (1995).

Cavalcanti (1995), described about 1.82% of the specimens in which the circumflex and the anterior descending branches arose directly from the aorta. In the present study, in one specimen, an anomalous circumflex branch arose directly from anterior aortic sinus, as described earlier.

Beginning usually as a direct continuation of main LCA, the anterior descending branch gently curves around the base of pulmonary artery to enter the anterior interventricular sulus to reach the apex of the heart. It reaches the apex almost always terminating there in one-third of specimens, but more often turning around the apex into the posterior inter- ventricular sulcus, in which it traverses a third to half its length, to meet the twigs of the corresponding right coronary ramus. (Table-IV)

Table-IV: Termination of Left Anterior Descending Branch

Termination James 1961 Present study
NO. (%) NO. (%)
Anterior Apex 18 (17) 8 (8)
Posterior Apex 24 (23) 12 (12)
2-5 Cms up PIVS 44 (42) 80 (80)
> 5 Cms up PIVS 20 (18)    
Total 106 (100) 100 (100)

Table -IV gives a comparison of the termination of LAD, between the present study and that of James (1961).

Unlike the anterior descending branch, the left circumflex artery does not usually begin as a simple continuation of the main LCA, but most often at an angle nearly perpendicular to it.

Table- V: Termination of Left Circumflex Artery

Point of Termination James (1961) Present Study
No. (%) No. (%)
Before Obtuse Margin 1 (1) 3 (3)
At Obtuse Margin 22 (20) 13 (13)
Between Obtuse margin and crux 64 (60) 67 (67)
At Crux 9 (9) 6 (6)
Beyond Crux 9 (9) 11 (11)
Not Present 1 (1) - -
Total 106 (100) 100 (100)

Table-V gives a comparison of termination of Left circumflex artery in the present study with that of James, 1961.

The inverse relationship between the RCA and left circumflex branch is most simply expressed as right or left dominance, depending on which artery gives rise to the PIVA (James, 1961). The origin of posterior inter ventricular artery from right coronary artery is the commonest anatomy in man, and referred to as RIGHT DOMINANCE, which occurred in 89% of the hearts in our study and a LEFT DOMINANCE, was observed in 11%. The results of the present study are compared with those of caval Cavalcanti (1995) in Table VI.

Table-VI: Dominant Circulation (% age)

Dominant (PIVA) Artery Cavalcanti (1995) Present Study
Right 88.18 89
Left 11.82 11


I am deeply indebted to Dr. K. R. SRINIVASAN Professor and Head, Department of Anatomy, Thanjavur Medical College, Thanjavur for his constant guidance, encouragement and untiring technical help rendered throughout the period of this study.


  1. Baptista, C.A. (1991) : Types of division of left coronary artery and the ramus diagonalis of the human heart. Japanese Heart Journal. 32(3) : 323- 335.
  2. Baroldi, G. and Scomazzoni, G. (1956) : The collaterals of the cornonary arteries in normal and pathological hearts. Circulation Research 4 : 223-229.
  3. Bekedam, M.A. and Vligen, H.W. (1999) : Diagnosis and management of anomalous origin of right coronary artery from the left coronary sinus. International Journal of cardiologic Imaging 15 (3) : 253 - 258.
  4. Caetano, A. G and Lopes, A.C. (1995) : Critical analysis of the clinical and surgical importance of the variations in the origin of sino-artrial node artery of the human heart. Rev. Assoc Med Brass 41 (2) : 94 - 102.
  5. Cavalcanti, J.S. (1995) : Anatomic variations of the coronary arteries. Arq Bras Cardiology 65 (6) : 489-492.
  6. Engel, H.J. and Torres, C. (1975) : Major variations in anatomical origin of the coronary arteries-angiographic observations in 4,250 patients without associated congenital heart disease. Cathet. cardiovascular Diagnosis 116 ( 5) : 157-169.
  7. James, T.N. : Anatomy of the coronary arteries. 1st edition ; Hoeber Med Div, Harper & Row : New York. (1961).
  8. Mongiardo, R. (1991) : Anomalous coronary arteries - a report of 2 cases of single coronary artery. Cardiologia 36 (2) ; 143-146.
  9. Schlesigner, M.J and Zoll, P.M. (1949) : The conus artery - a third coronary artery. American Heart Journal. 38: 823.
  10. Taylor, A.M. and Thorne, S.A. (2000): Coronary artery imaging in grown up congenital heart disease complementary role of megnetic resonance and x-ray coronary angiography. Circulation 101 (14) : 1670-1678.
  11. Uemura, H. (1999) : Ventricular Morphology and coronary arterial anatomy in hearts with isometric atrial appendages. American Thoracic Surgery. 67 (5) : 1403 - 1411.
  12. Williams, P.L.; Bannister, L.H; Berry, M.M; Collins. P; Dyson, M; Dussek, J.E. Ferguson, M.W.J. Gray's Anatomy In : Circulatory system 38th Edn. Churchill Livingstone. U.S.A : pp 1505-1510. (1995).


Missing Image

Fig: 1 Quadrifurcation And Pentafurcation of LCA


Missing Image

Fig. 2 Anomalous Branch of LCA


Missing Image

Fig. 3 Right And Left Dominant Circulation

Access free medical resources from Wiley-Blackwell now!

About Indmedica - Conditions of Usage - Advertise On Indmedica - Contact Us

Copyright © 2005 Indmedica