Mediastinum Flashcards
Superior boundary of mediastinum
Superior Thoracic Aperture
Inferior boundary of mediastinum
Diaphragm
Anterior boundary of mediastinum
Sternum
Posterior boundary of mediastinum
Thoracic vertebrae
Lateral boundary of mediastinum
Lungs and pleurae
Superior boundary of superior mediastinum
Superior thoracic aperture
Inferior boundary of superior mediastinum
horizontal plane
Anterior boundary of superior mediastinum
manubrium of sternum
Posterior boundary of superior mediastinum
T1 - T4
Lateral boundary of superior mediastinum
Lungs and Pleurae
Contents of Superior Mediastinum
Remnant of thymus Brachiocephalic veins and SVC Pulmonary trunk and pulmonary artery Aortic arch and branches Trachea Vagus N. Oesophagus Phrenic N Cardiac Plexus Left recurrent laryngeal N. Thoracic duct and lymphatics
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Superior boundary of anterior mediastinum
horizontal plane
Inferior boundary of anterior mediastinum
diaphragm
anterior boundary of anterior mediastinum
body of sternum and Xiphoid process
Posterior boundary of anterior mediaastinum
pericardium
Lateral boundary of anterior mediastinum
Lungs and Pleurae
Contents of anterior mediastinum
Remnants of thymus gland
superior boundary of posterior mediastinum
hornizontal plane
inferior boundary of posterior mediastinum
diaphragm
anterior boundary of posterior mediastinum
pericardium
posterior boundary of posterior mediastinum
T5 - T12 vertebrae
Lateral boundary of posterior mediastinum
Lungs and pleura
Contents of posterior mediastinum
Oesophagus Vagus N. Thoracic duct Azygous V. Descending aorta Right and left symphthetic trunks Lymph nodes
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superior boundary of middle mediastinum
horizontal plane
Inferior boundary of middle mediastinum
Diaphragm
Anterior boundary of middle mediastinum
Pericardium
posterior boundary of middle mediastinum
Pericardium
Lateral boundary of middle mediastinum
Lunds and Pleura
Contents of middle mediastinum
Pericardium and Heart
Great vessels:
- Ascending aorta
- SVA
- Pulmonary trunk
Cardiac plexus
Phrenic N and Pericardialphrenic vessels
From where does the thoracic duct arist?
Chyle Cistern
What is the position of the chyle cistern
Anterior to L2 body
Posterior to abdominal aorta
Between aorta and Right Crus of Diaphragm
Course of thoracic duct
1: At T12, passes through Aortic Hiatus
2: At level of T4/T5, inclines to left side of median plane
3: Ascends posterior to aortic Arch on left side of oesophagus to traverse (pass through) superior thoracic aperture
4: Arches laterally and then inferiorly - anterior to subclavian artery - to enter left venous angle.
What is the Azygous vein formed by?
Union of:
Right lumbar vein
Right subcostal vein
Where does the azygous vein end?
Joins the SVC
What are the tributaries of the Azygous Vein
Hemizygous v. Right posterior intercotal v. Right superior phrenic v. Right superior intercostal v. Right costal v. Oesophageal v. Bronchial v. Pericardial v.
What is the pericardium composed of?
Superficial fibrous pericardium
Deep two-layered serous pericardium
What is the visceral layer of the pericardium also called
epicardium
deep two-layered serous pericardium
What separates the parietal and visceral layers of the pericarium
pericardial cavity which is filled with fluid
What is type of tissues does the fibrous pericardium consist of
dense connective tissue
What lies on the top layer of the parietal pericardium
superficial fibrous pericardium
What attaches the fibrous pericardium to the diaphragm
pericardiacophrenic ligament
What is the location of the transverse sinus
located between the aorta and pulmonary trunk anteriorly
and the left atrium and superior vena cavae posteriorly
What is the function of the transverse sinus
connects the two sides of the epricardial cavity
What is the location of the oblique sinus
between the pulmonary veins and inferior vene cavae posteriorly
between the pulmonary veins and left atrium anteriorly
What is the function of the oblique sinus
it has no function - it is a blind sac (cul de sac)
What makes up the heart wall
Visceral layer of serous pericardium (epicardium)
Myocardium
Endocardium
Describe the blood supply of the pericardium
Pericardiacophrenic artery
Internal thoracic arteries
Internal thoracic veins drain the area
Describe the innervation of the pericardium
Phrenic nerves: Sensory fibres that control pain sensation
Sympathetic trunks: Vasomotor fibres
Parasympathetic supply comes from Vagus nerve
What is the position of the heart
Middle mediastinum
Behind body of sternum and 2nd - 6th costal cartilages
One third lies to the right
Two thirds lies to the left
Opposite to T5 - T8 vertebrae (supine position)
Opppposite to T6 - T9 vertebrae (erect position
Name the four borders of the heart
Superior
Right
Inferior
Left
Describe the superior border of the heart
Formed by the two atria
Right 3rd costal cartilage on right side of sternum
to
2nd intercostal space on left side of sternum
Describe the right border of the heart
Formed by the right atria
Extends from right 3rd costal cartilage to near right 6th costal cartilage
Describe the inferior border of the heart
mainly formed by right ventricle and slightly by left ventricle
Sternal end of right 6th costal cartilage
to
midclavicular line in left 5th intercostal space
Describe the left border of the heart
Formed mainly by left ventricle and partly by left auricle
Left 2nd intercostal space
to
midclavicular line in left 5th intercostal space
Name the three surfaces of the heart
sternocostal
posterior
diaphragmatic
What is the sternocostal surface of the heart formed by
RA, RV, LV, Left Auricle
What is the posterior surface of the heart formed by
2/3: LA
1/3: RA
What is the diaphragmatic surface of the heart formed by
2/3: LV
1/3: RV
What is the “BASE” of the heart?
Posterior surface of the heart
What are the three openings for the right atrium
SVC
IVC
Coronary Sinus
What are the notable internal features of the right atrium
Anterior surface roughed by pectinate muscles Posterior surface is smooth SA node Cristae terminalis Fossa ovalis Limbus fossa ovalis Tricuspid valve
Where is SA node located
Superior extent of cristae terminalis (separates anterior part from posterior), near the opening of SVC
What is the embryological origin of posterior surface of right atrium
Sinus venosum
What are the notable internal features of the left atrium
pectinate muscles
bicuspid valve
What are the features that mark the ventricular walls
papillary muscles and trabeculae carneae
What are the differences of the right ventricle when compared to the left ventricle
Walls 3x thinner
Trabeculae carnae are coarse and few
Three papillary muscles
Conrdae tendinae are few and short
Conical cavity shorter
Moderator band
What are the differences of the left ventricle when compared to the right ventricle
Walls 3x thicker
Trabeculae carnae are fine and numerous
Two papillary muscles
Chordae tindinae are more and long
Conical cavity longer
No moderator bank
Describe the moderator band. What is it also called?
Also called septomarginal trabecula
Specilised trabecula in RV extending from right side of ventricular septum to base of anterior papillary muscle
Carries right branch of bundle of HIS
What makes up the heart valves
Endocardium with a connective tissue core
What is the right AV valve
Tricuspid valve
what is the left AV valve
Biscuspid (mitral) valve
Where does the aortic semilunar valve lie
between left ventricle and the aorta
Where does the pulmonary semilunar valve lie
between right ventricle and pulmonary trunk
What forms the “lub”
closing of the atrioventricular valves
What forms the “dub”
closing of the semilunar valves
What is the location of the aortic valve
oblique
posterior to sternum at level of 3rd intercostal space
What is the site for auscultation of the aortic valve
2nd right intercostal space, near the sternal border
What is the location of the pulmonary valve
3rd costal cartilgae at the left side of the sternum
What is the site for auscultation of the pulmonary valve
2nd left intercostal space, near the sternal border
What is the location of the tricuspid valve
posterior to the body of sternum
At right 3rd/4th intercostal spaces
What is the site for auscultation of the tricuspid valve
5th right intercostal space, near the sternal border
What is the location of the mitral valve
posterior to the sternum, at the 4th left costal cartilage
What is the site for auscultation of the mitral valve
5th left intercostal space - in the midclavicular line