5. Mediastinum + Heart II Flashcards
Atria (Atrium)
Thinner walls
Pump blood to adjacent chambers
Ventricles
Thicker walls
Pump blood to lungs, body
Septae
Interatrial septum
Interventricular septum
Grooves
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Coronary (atrioventricular) groove
Anterior interventricular groove
Posterior interventricular groove
Coronary Arteries
Arise from ascending aorta
Bring oxygen rich blood to heart
R and L
Right Coronary Artery (RCA)
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Travels in coronary groove
Sinoatrial (SA) nodal bunch
Right marginal branch
Posterior interventricular branch
Left Coronary Artery (LCA)
Short segment, branches quickly
Anterior interventricular branch (LAD: left anterior descending)
Circumflex branch
L marginal branch
Myocardial Infarction (MI)
aka heart attack
area of heart muscle that has undergone necrosis
usually caused by ischemia due to occlusion of coronary artery
Common Sites of Coronary Artery Occlusion
- LAD
- RCA
- Circumflex
- LCA
Coronary Bypass Surgery
Treatment for MI
Technique used to shunt blood around narrowed or blocked coronary arteries
Graft alternate vessel to ascending aorta
- internal thoracic artery
- great saphenous vein
Venous Drainage
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Coronary sinus
- great cardiac vein
- middle cardiac vein
- small cardiac vein
Coronary Sinus
Drains into R atrium
Lies in coronary groove
Great Cardiac Vein
Anterior interventricular groove
Travels with anterior interventricular artery
Middle Cardiac Vein
Posterior interventricular groove
Travels with posterior interventricular groove
Small Cardiac Vein
Travels along inferior border of heart with R (?) marginal artery
Right Atrium
Connects to openings of IVC, SVC, coronary sinus
Fossa Ovalis
R Auricle
Right Auricle
Remnant of primordial heart
Pectinate muscle: ridged muscles on wall
Crista terminalis: ridge separating auricle and smooth posterior wall
Fossa Ovalis
Oval shaped depression in interatrial septum
Remnant of embryonic foramen ovale
Right Ventricle
Trabeculae carneae muscle
3 papillary muscles (anterior, posterior, septal)
Chordae tendinae: extend between papillary muscle and cusps of valve
Interventricular septum
Septomarginal trabecula
Tricuspid Valve
UNDERSTAND MECHANISM OF STAYING CLOSED
aka R atrioventricular valve
Between R atrium and R ventricle
3 cusps
Septomarginal Trabecula
aka Moderator Band
Muscle bundle extending from interventricular septum to anterior papillary muscle
Short cut for conductance MORE?
Pulmonary Valve
3 cup shaped cusps
3 pulmonary sinuses - fill with blood during relaxation - keeps valve closed
Pulmonary Veins
4 total (2L, 2R)
Dump oxygen rich blood into L atrium
Left Atrium
Openings of pulmonary veins
Left auricle with pectinate muscles
Mitral Valve
aka Left atrioventricular valve
Connects L atrium to L ventricle
Two cusps
Opens passively during atrial contraction
Left Ventricle
Walls are twice as thick as R ventricle
Trabeculae carneae (ridged muscles of walls)
2 Papillary muscles (prevent backflow, hold mitral valve closed during ventricular contraction)
Chordae tendineae (extend between papillary muscles and mitral valve)
Aortic Valve
3 Cup shaped cusps
3 Aortic sinuses
Connects L ventricle to ascending aorta
Sinuses fill with blood - hold valve closed
Difference from pulmonary valve: openings for coronary vessels
Postnatal Circulation (part 1)
-IVC/SVC/coronary sinus
-R atrium
(tricuspid valve)
-R ventricle
(pulmonary valve)
-pulmonary trunk, L and R pulmonary arteries
-Lobar arteries
-Segmental arteries
Postnatal Circulation (part 2)
-Pulmonary veins
-L atrium
(mitral valve)
-L ventricle
(aortic valve)
-Ascending aorta
-Arch of aorta
-Descending (thoracic) aorta
-Body
Fetus
Lungs are nonfunctional
(oxygen from placenta)
Bypasses in circulation for liver and lungs (3)
Fetal Circulation (bypasses)
Liver: ductus venosus
Heart: foramen ovale, ductus arteriosus
Fetal Circulation (1)
- oxygen rich blood from placenta enters fetus via umbilical vein (unpaired)
- DUCTUS VENOSUS leads directly into IVC (bypassing liver)
- IVC
- R atrium
- FORAMEN OVALE (no need to oxygenate blood in lungs, bypasses lungs)
- L atrium
- L ventricle
- Ascending aorta, aortic arch, descending aorta
- Body (?)
- Umbilical arteries (paired)
Fetal Circulation (2)
- oxygen poor blood (from head, neck) returns to heart
- SVC
- R atrium (O rich and O poor mix a little in here but not really)
- R ventricle
- Pulmonary Trunk
- DUCTUS ARTERIOSUS (ejects blood out pulmonary trunk and into aortic arch distal to branches supply baby brain)
- Body (?)
- Umbilical arteries (paired) to placenta
Fetal Circulation (adult remnants)
Fossa ovalis: foramen ovale (closure in first 3 months)
Ligamentum arteriosum: ductus arteriosus (closure in first 3 weeks)
Round ligament of liver: ductus venosus
Medial umbilical ligaments: umbilical arteries
Sinoatrial (SA) Node
Pacemaker of the heart
Initiates impulse for contraction of cardiac muscle of atria - sets heart rate
Located at junction SVC-R atrium
SA Node (innervation)
Sympathetic: stimulates
-increases heart rate, force of contraction
Parasympathetic (vagus nerve): inhibit
-decreases heart rate, force of contraction
Atrioventricular (AV) Node
Located in interatrial septum
Receives SA node signal via atrial walls
AV Bundle
aka Bundle of His
Located in interventricular septum
R bundle: stimulates R ventricle, moderator band
L bundle: stimulates L ventricle
Moderator Band
Conveys a portion of R bundle branch
Active role in heart contraction
Posterior Mediastinum
Posterior to heart
Anterior to vertebrae
Esophagus
Fibromuscular tube, typically flattened
Between pharynx and stomach
Posterior to trachea
Posterior to base of heart
Anterior to vertebral bodies
To the R of thoracic aorta
Passes through esophageal hiatus, travels with vagus nerves
Thoracic (Descending) Aorta (abdominal branches)
Bronchial arteries
Esophageal arteries
Posterior intercostal arteries
After diaphragm, name changes to abdominal aorta
Azygos System
Azygos vein
Accessory hemiazygos vein
Hemiazygos vein
Azygos Vein
R of midline
Collects from:
- bronchial veins
- esophageal veins
- posterior intercostal veins
- subcostal veins
- lumbar veins
Drains into SVC
Accessory Hemiazygos Vein
L of midline
Joins azygos vein
Superior to T9
Hemiazygos Vein
L of midline
Joins azygos vein
At T9 level
Thoracic Duct
Collects lymph from most of body (75%)
Drains into L venous angle (where L subclavian and L internal jugular veins join)
Begins at chyle cistern
Right Lymphatic Duct
Located in root of neck
Collects lymph from R upper quadrant (R side of head, neck, thorax, R UE) (25%)
Drains into R venous angle (where R subclavian and R internal jugular veins join)
Abdominal Organ Sympathetic Innervation
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Via thoracic splanchnic nerves - convey info from sympathetic trunk to abdominal organs
- Greater splanchnic nerves
- Lesser splanchnic nerves
- Least splanchnic nerves
