Embryology - 1 | Medical Science Optional Notes for UPSC PDF Download

Heart

Circle of Willis

• Circulus arteriosus 
• Interpeduncular fossa

Clinical Relevance:

• Excess or Redundancy
• Aneurysms
• Subclavian Steal Syndrome

Coronary Circulation

Coronary Dominance

• Chest Pain (Angina)
• Heart Attack (Myocardial Infarction)
• Imaging of Coronary Arteries (Coronary Angiography)
• Non-Surgical Artery Opening (Percutaneous Angioplasty)
• Coronary Artery Bypass Grafting (CABG)
• MR (Murmur) - More prevalent in Posterior Descending Artery (PDA) infarct?
• Does Coronary Circulation Take Place During the Diastolic Phase?
• "Widow-Maker" Artery?

Development of Heart

The heart originates from angioblastic tissue derived from the midline splanchnopleuric coelomic epithelium of the lateral plate mesoderm.

Key Developmental Stages of the Heart:

• Formation of the heart tube
• Expansion and folding of the heart tube
• Division of the developing heart
• Formation of the sinus venosus, its derivatives, and the development of the right atrium
• Emergence of the primary pulmonary vein, its derivatives, and the development of the left atrium
• Growth and maturation of the ventricles

1) The Development of Heart Tube

2) Growth and folding of the heart tube

3) Partitioning of Developing Heart

4) The sinus venosus, its derivatives, and development of the right atrium

5) The primary pulmonary vein, its derivatives, and development of left atrium
6) Development of Ventricles

Congenital Anomalies of Heart

• Dextrocardia 
• Atrial septal defects 
• Ventricular septal defects 
• PDA
  TOF
  Ebstein's anomaly 
• Transposition of the great arteries 
• TAPVR
• Aortic stenosis

Anatomy of Right Atrium

The right atrium, positioned in the upper right section of the heart, receives deoxygenated blood from the body. It then propels this blood into the right ventricle through the right atrioventricular opening, contributing to the formation of the heart's right border and constituting parts of the upper border, the sternocostal aspect, and the cardiac silhouette.

External Features

• This chamber exhibits vertical elongation, receiving the superior vena cava at its upper extremity and the inferior vena cava at its lower end.
• The upper extremity extends to the left to create the right auricle. The auricle covers the base of the ascending aorta and partially overlaps the infundibulum of the right ventricle.
• Running along the right border of the atrium, there exists a shallow vertical groove that extends from the superior vena cava above to the inferior vena cava below. This groove is termed the sulcus terminalis and is formed by an internal muscular ridge known as the crista terminalis.
• The upper segment of the sulcus accommodates the sinuatrial or SA node, functioning as the heart's pacemaker.
• The right atrioventricular groove separates the right atrium from the right ventricle. It is generally vertical and houses both the right coronary artery and the small cardiac vein.

Tributaries of Right Atrium

Right Atrium Inlets or Tributaries:
(a) Upper vena cava
(b) Lower vena cava
(c) Coronary sinus
(d) Anterior cardiac veins
(e) Venae cordis minimi (Thebesian veins)
(f) Right marginal vein

Heart - Repeats

1. Describe the main events in the development of heart and explain its common congenital anomalies? (1994) 
2. Right Atrium of Heart (1996) 
3. Describe the coronary circulation of heart and add a note on its applied anatomy (1997). 
4. Describe the development of rights and left Atria. Mention the congenital malformations associated with its development (1999) 
5. Write in brief anatomy of right atrium. Discuss errors in development leading to various congenital malformations of heart (2004). 
6. Give an account of blood supply of heart. Add a brief note on its applied anatomy (2006). 
7. Describe the development of heart chambers. Mention the common congenital anomalies and explain the developmental reasons for them. (2010) 
8. Describe the development of interatrial septum. (2016) 
9. Draw a diagram to depict the blood flow in left versus right coronary artery. (2016) 
10. Describe the Coronary Arteries. Add a note on cardiac dominance. (2018)