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Mnemonic: "A Cute Male Prefers Small Parties"
A → Artery to SA node
C → Conus branch
M → Marginal branch (Right marginal)
P → Posterior interventricular (descending) artery
S → Septal branches
P → Posterior ventricular branches
(Helps recall all major branches in their anatomical order.)
Mnemonic: "Lefties Can Aim Straight"
L → Left coronary artery
C → Circumflex artery
A → Anterior interventricular artery (LAD)
S → Septal and diagonal branches
Mnemonic: "Endo, Myo, Epic — three coats thick!"
Endocardium → Inner endothelial lining
Myocardium → Muscular middle layer
Epicardium → Outer serous covering
(Easy to recall histological arrangement of heart wall.)
Mnemonic: "SIVC Cans"
S → Superior vena cava
I → Inferior vena cava
V → Coronary sinus
C → Cardiac veins (anterior)
A → Atrioventricular orifice
N → Nodal (SA node region)
S → Sinus venarum (smooth part)
Mnemonic: "MI-TRI / AORT-PUL"
First sound (S₁): Closure of Mitral and Tricuspid valves
Second sound (S₂): Closure of Aortic and Pulmonary valves
Mnemonic: "Oval Ducks Venously Turn Medial"
Oval → Foramen ovale → Fossa ovalis
Ducks → Ductus arteriosus → Ligamentum arteriosum
Venously → Ductus venosus → Ligamentum venosum
Turn → Umbilical vein → Ligamentum teres hepatis
Medial → Umbilical arteries → Medial umbilical ligaments
Mnemonic: "SAAV His Right Purkinje"
S → SA node
A → Atrial musculature
A → AV node
V → AV bundle (Bundle of His)
His → His bundle branches
Right Purkinje → Right and left Purkinje fibers
(Recalls sequence of conduction in the heart.)
Mnemonic: "PROVe it!"
P → Pulmonary stenosis
R → Right ventricular hypertrophy
O → Overriding of aorta
V → Ventricular septal defect
Mnemonic: "Skin Fascia Muscle Cartilage Pleura Pericardium"
Skin
Superficial fascia
Pectoralis major
Costal cartilage (5th or 6th intercostal space)
Internal intercostal muscle
Parietal pleura (small portion)
Fibrous pericardium
Parietal layer of serous pericardium
Mnemonic: "Trunk Bulges, Vents and Atriums Split"
Truncus arteriosus → Aorta and pulmonary trunk
Bulbus cordis → Right ventricle and outflow tracts
Primitive ventricle → Left ventricle
Primitive atrium → Rough parts of both atria
Sinus venosus → Smooth part of right atrium and coronary sinus
The heart is a hollow, muscular organ about the size of a closed fist, weighing around 300 g in males and 250 g in females.
It lies within the middle mediastinum, enclosed by the pericardium, and is slightly tilted to the left.
The apex of the heart lies in the 5th left intercostal space, 9 cm from the midline.
The base of the heart is formed mainly by the left atrium, while the apex is formed entirely by the left ventricle.
The right border of the heart is formed by the right atrium, and the inferior border by the right ventricle.
The fibrous pericardium is continuous above with the adventitia of great vessels and below with the central tendon of diaphragm.
The transverse pericardial sinus separates the aorta and pulmonary trunk (in front) from the superior vena cava and left atrium (behind) — important in cardiac surgery for clamping vessels during bypass.
The oblique sinus is a blind recess behind the left atrium, between the pulmonary veins.
The pericardium receives blood supply from the pericardiophrenic artery (branch of internal thoracic artery) and is innervated by the phrenic nerve (C3–C5).
The right and left coronary arteries arise from the anterior and left posterior aortic sinuses, respectively.
Coronary dominance is determined by which artery gives rise to the posterior interventricular artery:
Right dominance: 70%
Left dominance: 10%
Co-dominance: 20%
The left anterior descending (LAD) artery is the most commonly occluded vessel in coronary artery disease.
Coronary veins drain mainly into the coronary sinus, which opens into the right atrium.
Right atrium: Contains fossa ovalis, crista terminalis, and openings of SVC, IVC, and coronary sinus.
Right ventricle: Has trabeculae carneae, moderator band, and tricuspid valve guarding the atrioventricular orifice.
Left atrium: Receives four pulmonary veins; smooth inside except for auricular pectinate muscles.
Left ventricle: Thickest chamber, contains bicuspid (mitral) valve, aortic vestibule, and aortic valve.
Atrioventricular valves: Tricuspid (right), Mitral (left).
Semilunar valves: Aortic and Pulmonary.
The aortic valve lies behind the left margin of the sternum at the level of the 3rd intercostal space, while the pulmonary valve lies higher.
Valves open and close passively due to pressure differences, not muscular control.
Papillary muscles and chordae tendineae prevent valve prolapse during ventricular contraction.
SA node (pacemaker): Upper end of crista terminalis near SVC opening.
AV node: Lower part of interatrial septum near coronary sinus opening.
AV bundle (Bundle of His): Only electrical link between atria and ventricles.
Purkinje fibers: Subendocardial conducting fibers ensuring synchronized contraction.
Normal heart rate: 70–75 beats/min (sinus rhythm).
Oxygenated blood from placenta enters via umbilical vein.
Ductus venosus → bypasses liver to join IVC.
Foramen ovale → directs blood from right to left atrium.
Ductus arteriosus → connects pulmonary trunk to aorta.
Umbilical arteries → return deoxygenated blood to placenta.
At birth, the lungs expand, pressure in left atrium rises → foramen ovale closes.
All fetal shunts close functionally within hours and anatomically within weeks after birth.
| Foetal Structure | Adult Derivative |
|---|---|
| Foramen ovale | Fossa ovalis |
| Ductus arteriosus | Ligamentum arteriosum |
| Ductus venosus | Ligamentum venosum |
| Umbilical vein | Ligamentum teres hepatis |
| Umbilical arteries | Medial umbilical ligaments |
Pericardial effusion → fluid accumulation compresses heart (cardiac tamponade).
Atrial septal defect (ASD): Failure of foramen ovale closure.
Ventricular septal defect (VSD): Failure of membranous septum formation; most common congenital heart defect.
Tetralogy of Fallot: Cyanotic congenital defect (PROV mnemonic).
Patent ductus arteriosus (PDA): Ductus arteriosus remains open → left-to-right shunt.
Angina pectoris: Transient myocardial ischemia without necrosis; relieved by nitrates.
Myocardial infarction (MI): Irreversible necrosis of cardiac muscle due to coronary blockage.
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