Chest wall (223-237)

Question 1

Name the branches of subclavian artery. What separates them?;

Answer 1

VIT C&D.
Vertebral, Internal throacic artery, Thyrocervical, Costocervical, Dorsal scapular.
1st part medial to anterior scalene (VIT arteries).
2nd part posterior to anterior scalene (C artery).
3rd part lateral border of anterior scalene to lateral border of first rib (D)

Question 2

Which arteries supply the anterior and posterior chest walls?;

Answer 2

Anterior- internal throacic/mammary artery.
Posterior- Posterior intercostal arteries (branches of descending thoracic aorta). Supereme intercostal arteries [1st and 2nd ribs] (branch of costcervical trunk which is branch of subclavian)

Question 3

Which veins drain the anterior and posterior chest walls?;

Answer 3

Anterior- intercostal veins -> internal thoracic/mammary. Posterior- Azygous venous system on right and hemiazygous on left. Supreme intercoastal veins [1st and 2nd ribs]

Question 4

Name the layers you would go through when inserting an intercoastal chest drain;

Answer 4

Skin, subcutaneous fat, superficial fascia, external intercoastal muscle, internal intercoastal muscle, innermost intercoastal muscle, endothroacic fascia, parietal pleura, pleural cavity

Question 5

What is the triangle of safety for interesting an intercoastal chest drain?;

Answer 5

Anterior- lateral border of pectoralis major. Posteriorly- midaxillary line (not lat dorsi). Inferiorly- 6th intercoastal space (go in 5th intercoastal space)

Question 6

Name three key complications thay may be encountered following an intercoastal chest drain insertion;

Answer 6

1. Long thoracic nerve damage (winged scapular). 2. Intercoastal nerve (just below rib). 3. intercoastal arterial or venous bleed)

Question 7

What are the important structures at the Angle of Louis (manubriosternal junction)?;

Answer 7

T4/T5 level. (RATPLANT). Rib 2. Aortic arch. Tracheal bifurcation (carina). Pulmonary trunk bifurcation into right & left. Ligamentum arteriorsum. Azygous drains into SVC. Nerves- left recurrent laryngeal nerve loops around arch of aorta. Thoracic duct crosses from right to left. Superior mediastium separated from inferior mediastinum.

Question 8

What are the contents of the superior mediastinum?;

Answer 8

Great vessels- arch of aorta with three major branches (brachiocephalic, left common carotid artery, left subclavian), Superior Vena Cava with branches such as azygous, brachiocephalic veins etc.
Nerves- right and left vagus nerves, phrenic nerves, cardiac plexuses and sympathetic trunk.
Other- thymus, trachea, oesophagus, thoracic duct.

Question 9

What are the contents of the anterior mediastinum?;

Answer 9

Sternopericardial ligaments, lymphatics, thymus extends into the anterior mediastinum in childen (recedes during puberty to superior mediastium only)

Question 10

What are the contents of the middle mediastinum?;

Answer 10

Organs- heart, pericardium, tracheal bifurcation. Great Vessels- ascending aorta, pulmonary trunk, superior vena cava. Nerves- cardiac plexus, left and right phrenic nerve. Lymphatics.

Question 11

What are the contents of the posterior mediastinum?;

Answer 11

Vessel- thoracic aorta, aygous system of veins. Other/organs- oesophagus, thoracic duct. Sympathetic trunks

Question 12

Where does the thoracic duct commence and what is its course?;

Answer 12

Orginates from the cisterna chyli in abdomen and enters mediastinum via aortic hiatus (T12). Ascends anterior to T6-12 vertebrae before crossing right to left at T4/5. Contiues to ascend up through superior mediastinum posterior to aorta and left of oesophagus. Then empties into the juction of left suclavian and internal jugular veins.

Question 13

What are the anatomical landmarks for subclavian vein central venous cannulation?;

Answer 13

Needle should be inserted approx 2-3cm infferior to the midpoints of the clavicle.

Question 14

What are the anatomical landmarks for internal jugular vein central venous cannulation?;

Answer 14

It is 2cm above the superior border of the calvicle, the clavicular head of the SCM is divided into three equal parts. The IJV lies posterior to the medial point.
The internal jugular vein lies superficial and lateral to the carotid artery. (However note there is anatomical variability for IJV unlike subclavian)

Question 15

What are the characteristic features of a typical thoracic vertebra?;

Answer 15

Presence of costal facets on transverse processes (articulate with tubercles of the ribs). Prescence of demi-facets on side of each vertebral body (articulate with head of ribs). Vertebral body is heart shaped. The spinous processes are long and slant inferiorly (offer increased protection to spinal cord).