Anatomy and Development Flashcards
Developing Heart Tube
Sinus venosus –> primitive atrium –> primitive ventricle –> bulbus cordis –> truncus arteriosus
- heart tube bends to the R –> inflow becomes dorsal
Endocardial Cushions
Contributes to:
- AV canals on R and L side
- Tricuspid and Mitral Valve
- Membranous portion of interventricular septum
- Closure of primary intraatrial foramen
Bulbar and Truncal Ridges
- neural crest mesenchyme
- forms spiral aorticpulmonary septum that divides bulbus cordis and truncus arteriosus into ascending aorta and pulmonary trunk
Aortic Sac and Arches
- aortic sac –> arch of aorta
- 4th arch: L = aortic arch, R = subclavian artery
- 6th arch: L proximal = L pulmonary, L distal = ductus arteriosus, R proximal = R pulmonary
Fetal Circulation
- ductus venosus shunts blood from L umbilical vein directly to liver and inferior vena cava
- blood from IVC –> foramen ovale –> L atrium
Postnatal Circulation
foramen ovale closes
- increased blood flow to lungs = increased pressure in L atrium
- decreased pressure in R atrium = no blood flow from placenta
Ductus arteriosus –> ligamentum arteriosum
- increased blood flow to lungs –> increased [O2] of blood
Left to Right Shunts
cyanosis several months or years after birth (tardive)
- ASD, VSD, patent ductus arteriosus
Right to Left Shunts
cyanosis early in postnatal life (3 T’s)
- Tetralogy of Fallot, Transposition of great arteries, Truncus arteriosus
Normal Heart Pressures
Pulmonary/Aortic = 1/6 ratio
- shunts: increased R ventricular or pulmonary pressure leads to fibrosis of lung
Stenosis and Atresia Definitions
Stenosis –> narrowing
Atresia –> failure to develop
Atrial Septal Defect
Left to right shunt, abnormal opening between atria
Results because of incorrect development of atria septum
- excessive resorption of primary septum (90%)
- incompetent foramen ovale due to hypoplastic growth (90%)
- inadequate development of primary septum (10%)
- sinus venosus defect (10%)
Can lead to
- R ventricular failure
- Paradoxical Embolism
Ventricular Septal Defect
- Left to right shunt, abnormal opening between ventricles
- Solitary: 90% involve membranous portion of ventricular septum
- Cyanosis tardive in long-standing cases
Patent Ductus Arteriosus
Left to right shunt, directs blood from pulmonary artery to aorta, if persists, blood goes from aorta to pulmonary artery
Congential anomaly associated with maternal Rubella infection!
Machinery like murmur
Tetralogy of Fallot
Right to Left Shunt, cyanotic
- VSD
- Pulmonary stenosis
- Overriding (large) aorta
- R ventricular hypertrophy
Transposition of great arteries
- Caused by straight division of bulbus cordis and truncus arteriosus due to failure of normal spiraling
- aorta originates from R ventricle, pulmonary artery originates from L ventricle
- incompatible with life unless VSD and PDA also occur
- occurs with diabetic mothers!
Truncus Arteriosus (persistent)
- common aorticpulmonary outlet receiving blood from both ventricles
- due to failure of bulbar and truncal ridges to develop
Coarctation of Aorta
- obstructive congenital heart defect caused by infolding of aorta near the ductus arteriosus
- Hypertension in upper extremities with weak pulses and lower blood pressure in lower extremities
Pulmonary stenosis and Atresia
defective development or aorticpulmonary septum
Visceral Pleura
serous membrane on surface of lungs
Parietal Pleura
lines walls of thoracic cavity
Lungs and lobes
R: superior, middle, inferior
- oblique and horizontal fissure
L : superior, inferior, lingula
- oblique fissure
RALS
Right lung –> pulmonary artery is Anterior to bronchi
Left lung –> pulmonary artery is Superior to bronchi
Atelectasis
collapsed and airless state of all or part of the lung
Pneumothorax
entry of air into pleural cavity
- pressure in the pleural cavity increases and the lung collapses
Spontaneous pneumothorax
rupture of bleb of bulla on lung surface
- typically with patient who is young, tall, and thin
Open pneumothorax
air flows easily in and out of open wound
Tension pneumothorax
wound is covered by skin or tissure and the wound closes after inspiration, trapping air in pleural cavity
3 esophageal constrictions
- Cricopharyngeus muscle
- Aorto-bronchial
- Esophageal Hiatus
Esophageal Plexus
formed be vagus nerves and sympathetic nerves of T1-5
- Parasympathetics (X) - increase parastalsis and glandular secretions
- Sympathetics (T1-5) - inhibit parastalsis
Achalasia
failure of smooth muscle fibers to relax –> no opening of sphincter
Descending aorta
3 branches
- posterior intercostal
- bronchial
- esophageal
Sympathetic Nerves in Thorax
Greater Splanchnic (T5-9) Lesser Splanchnic (T10-11) Least Splanchnic (T12) - all are preganglionic sympathetic fibers
Branches of aorta
BCL
Brachiocephalic Trunk
Left Common Carotid
Left subclavian artery
