Thoracic Cavity 1

Question 1

What is the function of serous membrane?

Answer 1

Allows movement, expansion and contraction of organs, Compartmentalise, lubricate potential spaces to prevent friction.

Question 2

Where will you find the viceral and parietal pleura layer?

Answer 2

Viceral is the serous membrane incontact with the lungs whereas the parietal layer is incontact with the thoracic wall and superior diaphragm.

Question 3

How many cavities is the thoracic cavity divided into and name them

Answer 3

Three compartments. Right and left pleural cavities and the mediastinum between them.

Question 4

What is the parietal pleura attached to?

Answer 4

Thorax wall, the fascia at the thoracic inlet, 1st rib and T1, Fibrous pericardium and other mediastinal structures and the Diaphragm

Question 5

What is the mediastinum?

Answer 5

The space between the two pleural sacs, sternum and the costal cartilage, thoracic vertebrae and diaphragm. It is mobile region to accommodate volume and pressure changes

Question 6

Name the different areas the mediastinum is broken up into?

Answer 6

Superior mediastinum, middle and the Inferior mediastinum (which further gets subdivided into the anterior, middle and postierior mediastinum)

Question 7

Describe the location of superior mediastinum

Answer 7

It is behind the maubrium, between the inlet and the sternal angle.

Question 8

Describe the location of inferior mediastinum

Answer 8

Inferior to transverse plane through the sternal angel and the diaphragm.

Question 9

What are the structres on the right side of the mediastinum?

Answer 9

These related to the right atrium and veins: SVC, arch of azygos and IVC

Question 10

What are the structres on the left side of the mediastinum?

Answer 10

Relate to left ventricle and arteries: Left common carotid artery, left subclavian artery, arch of aorta and thoracic aorta.

Question 11

What are the contents of the middle mediastinum

Answer 11

Heart, Pericardium, Origins of great vessels, smaller vessels (pulmonary veins) phrenic nerves and branches of the vagus nerve.

Question 12

What is the pericardium and its functions

Answer 12

It is a fibro-serous sac that encloses the heart and the roots of the great vessels. Its functions are anchoring the heart to surrounding tissue without compromising cardiac movement and prevent the overfilling of the heart.

Question 13

What are the layers the pericardium is comprised of?

Answer 13

Fibrous pericardium (external) and the serous pericardium (internal)

Question 14

What is the fibrous pericardium attached too?

Answer 14

Apex is fused with tunica adventitia of great vessels, anteriorly it is attached to sterno-pericardial ligament (to sternum and CC 3-6) and posteriorly is attached to the pericardiovertebral ligaments (5-8) and inferiorly it blends with the central tendon of the diaphragm

Question 15

What are the two layers of the serous pericardium?

Answer 15

Parietal - lines the inner aspect of the fibrous pericardium.
Visceral = epicardium.

Question 16

Where is the pericardial cavity? and how much fluid sits here and it function.

Answer 16

Between layers of serous pericardium. 10-15ml of fluid produced by serous pericardium. It reduces friction during contraction of the heart

Question 17

How are the transverse and oblique sinuses formed?

Answer 17

During embryological development the endocardial tube folds and invaginates into the serous pericardium.

Question 18

Where is the location of the Transverse pericardial sinus and when is it important?

Answer 18

It is posterior to the ascending aorta and pulmonary trunk and anterior to the SVC. Superior to left atrium and pulmonary veins. It is important in cardiac surgery. It used to separated the arterial and venous ends of the heart tube.

Question 19

Where is the location of the Oblique pericardial sinus?

Answer 19

It is a recess on the posterior aspect of the left atrium, on either sides are the pulmonary veins.

Question 20

What are the nerve supplies for the pericardium?

Answer 20

Sensory fibres from the phrenic nerve, vasomotor from the vagus nerve and the cardiopulmonary splanchnic nerves.

Question 21

What are the roots of the phrenic nerve and its journey?

Answer 21

Arises from C3,4,5 (keeps the diaphragm alive). It descends over scalenus anterior muscle and then enters the mediastinum between the subclavian vein and artery. It then passes anterior to root of lung, lies between fibrous pericardium and parietal pluera. It runs along SVC IVC and crosses the aortic arch over left ventrical

Question 22

What does the phrenic nerve supply?

Answer 22

Motor supply to the diaphragm and sensory supply to the mediastinal pariertal pleura, peritoneum and pleura related to central tendon of diaphragm and the parietal pericardium

Question 23

Where is the refereed pain for the phrenic nerve?

Answer 23

Back of neck, supraclavicular region and shoulder tip.

Question 24

What are the bounderies of the anterior medistinum?

Answer 24

Sternal body and xiphoid, pericardium and lungs with pleura

Question 25

What are the contents of the anterior mediasternum?

Answer 25

Thymus(in kids), internal mammary vessels, Lymph nodes, CT, fat and lower pole of thyroid.

Question 26

What tumours can arise in the anterior medistinum

Answer 26

Terrible 4s. Thymus, Thyroid Terrible lymphoma and teratoma

Question 27

What is the thumus?

Answer 27

Bilobed organ of lymphoid tissue, it is active until puberty and can extend from lower neck to 4th CC.

Question 28

What are the 3 planes of the superior mediastinum and what lies between them?

Answer 28

Venous, arterial and the trachea and oesophagus. The vagus and phrenic nerve lies within these planes.

Question 29

What are the contents of the venous plane? or what occurs here?

Answer 29

Brachiocephalic vein (BCV) formed by IJV and subclavian. The right and left BCV forms the SVC. The arch of azygos joins the SVC

Question 30

What occurs in the arterial plane?

Answer 30

The ascending aorta conticues as the aortic arch above the sternal angel. It curves up and backwards and then continues as the thoracic aorta in posterior mediastinum.

Question 31

What are the branches of the Aortic Arch?

Answer 31

Brachiocephalic trunk (divided into right subclavian and right common carotid), Left common carotid and the left subclavian.

Question 32

At what level does the pulmonary trunk divide and what does it divide into?

Answer 32

Divides at T4/5 disc into Right and left pulmonary arteries.