Anatomy of Thorax Flashcards
What fuses to become the primitive heart tube?
Paired endothelial tubes
What are the 5 regions of the pericardial cavity?
Sinus venosus, Atrium, Ventricle, Bulbus cordis and truncus arteriosis.
Sinus venosus becomes incorporated into what?
The atrium
What part of the pericardial cavity tube incorporates into the ventricle?
The bulbus cordis
How does the interventricular septum develop?
From the apex upwards towards the endothelial cushions
Fusion of what leads to the formation of the foramen secundum?
The septum primum fuses with the endocardial tissues
What two defects form the foramen ovale?
Septum secundum
Septum primum
What is the purpose of the foramen ovale:
Allows blood to go directly from the right to the left side f the heart in a developing foetus. The septum secundum acts as a valve like structure to facilitate this.
How does the foramen ovale close?
After birth there is an increased blood flow through the lungs which causes a rise in left atrial pressure - the septum primum is then pushed across to close the foramen ovale.
What is the name given to the residual dimple after the foramen ovale closes:
The fossa ovalis
What is the most common type of cardiac defect?
Ventricular septal defect
What defect causes increased load on the left ventricle and can lead to pulmonary hypertension?
Patent ductus arteriosus
When surgically (open) repairing a patent ductus arteriosus, what vessel must you take care to avoid?
The LEFT recurrent laryngeal nerve
What is reverse shunting
Right to left shunting / flow of blood
Increased ___________ flow leads to reverse shunting
Pulmonary
What defects can lead to reverse shunting
ASD, VSD and PDA
What is the name for cyanosis secondary to reverse shunting
Eisenmenger’s syndrome
What congenital condition can lead to Eisenmenger’s syndrome
Tetralogy of Fallot
What are the four components of tetralogy of fallot:
VSD
Stenosed pulmonary outflow tract
Right ventricular hypertrophy.
Wide aorta overriding the right and left ventricles.
The degree of cyanosis depends on the degree of what?
The severity of pulmonary outflow obstruction
When is notching of the rib inferior border seen on a CXR and what condition causes this?
When patient has enlarged intercostal arteries which become torturous
Caused by Coartication of the aorta
Delayed / weak / absent femoral pulses are seen in what condition:
Coartication of the aorta
What are the 4 developmental parts of the diaphragm?
Septum Transversum
Mesentery of the foregut
Ingrowth from the body wall
Pleuroperitoneal membrane
Which rib does the scalenus anterior insert onto?
Rib 1 - upper surface prominent tubercle
What vessel crosses the first rib infront of the scalene tubercle?
The subclavian vein
What is the incidence of cervical ribs?
1 in 200
( 1 in 500 if bilateral)
What is the superior border of the superior mediastinum?
Thoracic inlet
What is the onferior border of the superior mediastinum?
Continuous with the inferior mediastinum
What is the anterior border of the superior mediastinum?
Manubrium of sternum
What is the posterior border of the superior mediastinum?
Vertebral bodies of T1 to T4
What is the Lateral border of the superior mediastinum?
Pleura of lungs
What vessels are found in the superior mediastinum?
Arch of the aorta -
- brachiocephalic (right only),
- left common carotid
- left subclavian
Superior vena cava -
- Azygous vein
- Brachiocephalic vein
- Left intercostal vein
- Supreme intercostal vein
What nerves are found in the superior mediastinum?
Vagus nerve - right and left
Phrenic nerve
Cardiac nerves
Sympathetic trunk
List structures found within the superior mediastinum:
Thymis
Trachea
Oesophagus
Thoracic duct
What muscles are found within the superior mediastinum?
Sternohyoid
Sternothyroid
At what level is the mediastinum segregated into superior and inferior compartments:
T4 (aka sternal angle)
How is the inferior mediastinum segregated?
Anterior, middle and posterior sections
What forms the lateral border of the anterior mediastinum?
Mediastinual pleura
What forms the anterior border of the anterior mediastinum?
Body of sternum
Transversus thoracis muscles
What forms the posterior border of the anterior mediastinum?
Pericardium
What forms the roof of the anterior mediastinum?
Peridcardium
What forms the floor of the anterior mediastinum?
Diaphragm
What are the contents of the anterior mediastrinum:
No Major structures
Stern pericardial ligaments
Thymus can extend into the anterior mediastinum in children
What forms the anterior border of the middle mediastinum?
Anterior margin of the pericardium
What forms the posteroir border of the middle mediastinum?
The posteroir border of the pericardium
What forms the lateral border of the middle mediastinum
Mediastinal pleura of lungs
What forms the superior border of the middle mediastinum?
Imaginary line of the T4 vertebra / sternal angle
What forms the inferior border of the middle mediastinum?
Diaphragm
What organs are found in the middle mediastinum
Heart + pericardium
Tracheal bifurcation
L and R main bronchi
What vessels are found in the middle mediastinum?
Ascending aorta
Pulmonary trunk
Superior vena cava
What nerves are found in the middle mediastinum?
Cardiac plexus
Phrenic nerves L and R
What lymphatics are located within the middle mediastinum?
The tracheobronchial lymph nodes (form a gathering at the hila of the lungs)
What forms the lateral border of the posterior mediastinum?
Mediastinal pleura
What forms the anterior border of the posterior mediastinum?
Pericardium
What forms the posterior border of the posterior mediastinum?
T5 to T12
What forms the roof of the posterior mediastinum?
Sternal angle (imaginary line)
What forms the floor of the posterior mediastinum?
Diaphragm
What vessels are contained in the posterior mediastinum?
Thoracic aorta:
- Posterior intercostal arteries
- Bronchial arteries
- Oesophageal arteries
- Superior phrenic arteries
At what level does the thoracic aorta become the abdominal aorta?
T12
What else is contained in the posterior mediastinum?
Oesophagus
Oesophageal plexus
Thoracic duct
Azygous vein
Accessory hemizygous vein
Sympathetic trunks –> form lower thoracic splanchnic nerves
At what level does the oesophagus pass through the oesophageal hiatus of the diaphragm?
T10
Where does the thoracic duct originate>
Cisterna Chyli
What does the thoracic duct pass through in the diaphragm
The aortic hiatus
What nerves give branches to form the oesophageal plexus?
Left and right vagus nerves
What structure does the azygous vein drain into
Superior vena cava
What is unique about the thoracic vertebrae
They have costal facets on the transverse process
What is the role of the ligamentum flavum?
Connects the laminae of the adjacent vertebrae
What is the role of the interspinous ligament?
Connects the spinous process of the adjacent vertebrae
What are the anterior and posterior longitudinal ligaments?
Long ligaments which run the length of the vertebral column, covering the vertebral bodies and intervertebral discs.
What other vessel travels with the ascending aorta in the pericaridal sheath?
The pulmonary trunk
At what vertebral level does the aortic arch end?
T4
What connects the aortic arch to the pulmonary trunk?
The ligamentum arteriosum
What are the 3 main branches of the aortic arch?
Brachiocephalic Trunk
Left common carotid
Left subclavian artery
Where does the aorta typically coarticate?
At the insertion point of the ligamentum arteriosum (former ductus arteriosum)
What vessels come off the ascending aorta?
Left and right coronary artery
Where does the left and right coronary artery originate from?
The right and left aortic sinus at the level of the aortic valve
List the branches of the descending aorta from proximal to distal?
Bronchial arteries
Mediastinal arteries
Oesophageal arteries
Pericardial arteries
Superior phenic arteries
Intercostal and subcostal arteries
At what level does the aorta exit the diaphragm via the aortic hiatus?
T12
Define an aortic anuerysm?
Aortic dilation of >1.5cm
What symptom may suggest an aneurysm of the aortic arch and why?
Hoarse voice
Compression of the recurrent laryngeal nerve
Where are the intercostal nerves?
T1 - T11
11 pairs - run in between the the intercostal muscles
Where do the intercostal muscles lie
In the intercostal spaces.
What intercostal muscles are responsible for increasing the thoracic volume and elevating the ribs?
The external intercostal muscles
What is the role of the transversus thoracis?
Weakly depresses ribcage
Where is the transversus thoracis?
T2-T6
At what level does the IVC exit the diaphragm?
T8
What vessels pass through the caval hiatus?
The inferior vena cava
The terminal branches of the phrenic nerve
What is the arterial supply to the diaphragm>
The inferior phrenic arteries
Give 3 causes of a raised JVP:
Right heart failure
Pulmonary hypertension
SVC obstruction
What level is the cardioesophageal junction?
T11