Unit 10 · The Heart · Panic Mode

5 Minute Cram

⏱ 5 min Full Unit ↗
Walking into the hall. No prose. No explanations. Naked must-knows only — names, numbers, order. If you need the "why", it's too late for this sheet.

1. Cardiac Chambers — Inlets & Outlets

★★★ Most tested
Right Atrium — 3 in / 1 out
In: SVC · IVC · coronary sinus
Out: right AV orifice → tricuspid
Right Ventricle
In: tricuspid (ant/post/septal)
Out: pulmonary valve (3 semilunar)
Moderator band = R bundle branch
Left Atrium — 4 in / 1 out
In: 4 pulmonary veins (2R + 2L)
Out: left AV orifice → bicuspid/mitral
Left Ventricle
In: bicuspid (ant/post)
Out: aortic valve (3 semilunar)
Wall ~3× thicker than RV

2. Tricuspid & Bicuspid Complex — 4 Components Each

★★★ Define Q
① Fibrous ring
Right / left AV fibrous ring (annulus)
② Cusps
Tricuspid: 3 (anterior, posterior, septal) · Bicuspid: 2 (anterior, posterior)
③ Chordae
Chordae tendineae — prevent cusp inversion into atrium
④ Papillary mm.
Contract with ventricle, keep chordae taut → cusps seal during systole
Function: prevent backflow ventricle → atrium during systole

3. Conduction System — 5 Components in Order

★★★ Long Q
SA nodeRA near SVC · 60–100/min
→
Internodal tracts3 (ant/mid/post)
→
AV nodeinteratrial septum · 0.1s delay · 40–60/min
→
Bundle of His + R/L branchesR branch in moderator band
→
Purkinje plexussubendocardial · 30–40/min
Normal pacemaker = SA node Failsafe: SA → AV → Purkinje

4. Coronary Arteries — Origin & Branches

★★★ Long Q + MCQ
ArteryOriginMain Branches
RCARight aortic sinusPosterior IV branch · posterior LV branch · SA nodal br · AV nodal br
LCALeft aortic sinusLAD (anterior IV branch) · circumflex branch
MCQ trap: LCA from LEFT aortic sinus (not coronary sinus) Perfused during diastole

5. Pericardium & Surface Projection

Layers
Fibrous (outer) + serous parietal + serous visceral (epicardium)
Cavity
15–50 mL serous fluid
Nerve
Phrenic (C3–C5)
Apex
L 5th ICS · MCL · ~9 cm from midline
Auscultation
A = 2R ICS · P = 2L ICS · T = 4L sternal edge · M = Apex (5L ICS MCL)
"All Patients Take Medicine" → A · P · T · M
→ 15 min review → Day before ↗ Full unit 📝 Question Bank
All facts sourced from unit10_heart.html · Gray's 4e Ch3 p141–236 · Netter's 7th Plates 215–232