L28: Heart I

Question 1

Describe different layers of pericardium

Answer 1

• Pericardium = double walled sac enclosing heart and roots, it is attached to sternum
  1. ) Fibrous pericardium = fused to central tendon of diaphragm, inelastic and protects against overfilling
  2. ) Serous pericardium
  a. ) Parietal = fused to fibrous pericardium, reflects onto great vessels
  b. ) Visceral = around heart itself, aka epicardium

Question 2

What is the pericardial cavity?

Answer 2

• Potential space between parietal and visceral layer containing serous fluid, enabling heart to beat in frictionless environment

Question 3

Discuss reflection from visceral to parietal pericardium and what cavities are formed

Answer 3

• Visceral and parietal layers of serous pericardium are continuous, where they reflect onto one another at the aorta and pulmonary trunk, posterior space = transverse pericardial sinus
• Reflection at SVC, IVC and pulmonary veins = oblique pericardial sinus

Question 4

Describe relationship of borders and surfaces of heart. What chambers do these pertain to?

Answer 4

Surfaces:

1. ) Sternocostal (anterior) = right ventricle
2. ) Diaphragmatic (inferior) = both ventricles, primarily left
3. ) Pulmonary (left) = left ventricle at cardiac notch

Question 5

Borders:

Answer 5

• Right = right atrium
• Inferior = right ventricle and apex of left ventricle
• Left = left ventricle and left auricle
• Superior = right and left auricles

Question 6

Correlate the borders of the heart to surface landmarks. Note what chambers of the heart correspond to these regions.

Answer 6

• Right border = R 3rd costal cartilage to R 6th costal cartilage = right atrium
• Inferior border = R 6th costal cartilage to L 5th IC space = right ventricle and apex left ventricle
• Left border = L 5th IC space to L 2nd costal cartilage = left ventricle and left auricle
• Superior border = L 2nd costal cartilage to R 3rd costal cartilage = right and left auricles

Question 7

Grooves and sulci of heart

Answer 7

• Coronary sulcus aka atrioventricular sulcus

- Anterior and posterior interventricular sulci (grooves)

Question 8

Chambers associated with valves of heart

Answer 8

• Right atrium to right ventricle via right atrioventricular valve or tricuspid valve
• Right ventricle to pulmonary trunk via pulmonary semilunar valve
• Left atrium to left ventricle via left atrioventricular valve or bicuspid valve
• Left ventricle to ascending aorta via aortic seminlunar valve

Question 9

Cardiac skeleton function? What is it composed of?

Answer 9

• Composed of fibrocartilagenous tissue (can calcify)
• Divides atria from ventricles
• Provides barrier between atrial and ventricles for conduction
• Provides attachment for heart valves and myocardium

Question 10

Describe relationships of valves and myocardium to cardiac skeleton

Answer 10

• Tendon of conus arteriosus: aortic to pulmonary semilunar valves
• Left fibrous trigone: mitral valve to aortic semilunar
• Right fibrous trigone: AV valves to aortic semilunar

Question 11

What does the tendon of conus arteriosus connect?

Answer 11

• aortic to pulmonary semilunar valves

Question 12

What does the left fibrous trigone attach?

Answer 12

• mitral valve to the aortic semilunar

Question 13

What does the right fibrous trigone attach?

Answer 13

• AV valves to the aortic semilunar

Question 14

Describe internal anatomy of four chambers of heart

Answer 14

1. ) Right atrium: interatrial septum, fossa ovalis, pectinate muscles, opening to coronary sinus, IVC, SVC, sinus venarum (smooth surface), crista terminalis (texture change between pectinate and sinus venarum), tricuspid valve
2. ) Right ventricle: tricuspid valve, chorade tendinae, papillary muscles, trabeculae carneae, IV septum, moderator band (specialized muscle cell that conducts), conus arteriosus (area between ventricle and pulmonary semilunar), pulmonary semilunar valve
3. ) Left atrium: pulmonary veins, pectinate muscles (in left auricle), smooth atrium primarily, interatrial septum, mitral valve
4. ) Left ventricle: mitral valve, trabeculae carneae, papillary muscles, chordae tendinae, aortic vestibule (area between ventricle and aortic semilunar), aortic semilunar valve

Question 15

Discuss thickness of interventricular septum

Answer 15

• Thinner (membranous) part at superior portion

- Thicker (muscular) part at inferior portion

Question 16

Significance of pectinate muscles and sinus venarum

Answer 16

• Pectinate muscles are old baby heart muscle, mostly in right atrium, left auricle shows pectinate muscles
• Sinus venarum is derived from blood vessel

Question 17

Cusps of semilunar valves. Which have anterior and posterior, left and right?

Answer 17

• Pulmonary semilunar: has anterior cusp with right and left

- Aortic semilunar: has posterior cusp with right and left

Question 18

What are the aortic sinuses? Why is position important?

Answer 18

• Aka sinus of Valsalva. Dilations of ascending aorta, which occurs above aortic semilunar valve. Left sinus gives rise to left coronary artery. Right sinus gives rise to right coronary artery
• If they were located under aortic semilunar, heart would not get blood supply during diastole

Question 19

Describe anatomy of conducting system of heart and approximate locations of conducting fibers with their blood supply

Answer 19

• Conducting system is made up of cardiac muscle cells that are specialized for initiating and conducting impulses, not neural tissue
  1. ) SA node: at junction of SVC and right atrium, initiates impulse for contraction 70-80 bpm
  2. ) AV node: at posteroinferior region of interatrial septum, near coronary sinus, collects impulses from atria and distributes to ventricles. Can initiate impulses if needed at 40-60 bpm
  3. ) AV bundle (Purkinje fibers): located in IV septum and travels to ventricular myocardium via left and right bundle branches. Can initiate impulses at 20-40 bpm.

Question 20

Arterial coronary vasculature

Answer 20

• Right coronary artery from aorta into nodal artery (to SA node) and right marginal along right ventricle and travels around to posterior heart giving of posterior interventricular artery (if right dominant heart). Anastomoses with circumflex artery
• Left coronary artery from aorta divides into anterior interventricular artery (LAD) and circumflex artery that travels to posterior heart. Anastomoses with right coronary. Posterior interventricular artery can come from circumflex artery in left dominant heart. Anterior interventricular artery gives off diagonal branch sometimes.

Question 21

Venous coronary vasculature

Answer 21

• Great cardiac vein sits in anterior interventricular sulcus
• Middle cardiac vein sits in posterior interventricular sulcus
• Small cardiac vein is near marginal artery (right heart)
• Anterior cardiac vein typically runs over right coronary artery
• All except anterior cardiac vein drain into coronary sinus, which then drains to right atrium. Anterior drains directly into right atrium

Question 22

Node blood supply

Answer 22

• 60% of RCA supplies SA node and AV node

- 40% of LCA supplies SA node

Question 23

Describe nerve supply to the heart

Answer 23

• Cardiac plexus (T1-T4) composed of sympathetic trunks and vagus nerve

Question 24

Describe positions of auscultation areas. Actual locations of valves using surface anatomy.

Answer 24

• Auscultation areas are areas on surface of chest wall where you listen to blood flow through valves and chambers. Heart sounds result from turbulence of blood flow hitting closed valves, not from valves themselves. Lub results from AV valve closure. Dub results from semilunar valve closure.
  1. ) Aortic semilunar: right 2nd IC space
  2. ) Pulmonary semilunar: left 2nd IC space
  3. ) Tricuspid: lower left body of sternum
  4. ) Mitral: left 5th IC space
• Actual locations: in oblique line from left 3rd costal cartilage to right 6th costal cartilage (P A M T – pulm, aort, mitr, tric)