Thoracic II

Question 1

A 5 year old boy is playing with some small ball bearings. Unfortunately he inhales one. To which of the following lung regions is the ball most likely to settle?

	A.	Right lower lobe
	B.	Left main bronchus
	C.	Right upper lobe
	D.	Left lower lobe
	E.	None of the above

Answer 1

Right lower lobe

As the most dependent part of the right lung a small object is most likely to lodge here. Most objects will preferentially enter the right lung owing to the angle the right main bronchus takes from the trachea.

Question 2

A patient presents with superior vena caval obstruction. How many collateral circulations exist as alternative pathways of venous return?

	A.	None
	B.	One
	C.	Two
	D.	Three
	E.	Four

Answer 2

4
There are 4 collateral venous systems:
Azygos venous system
Internal mammary venous pathway
Long thoracic venous system with connections to the femoral and vertebral veins (2 pathways)

Despite this, venous hypertension still occurs.

Question 3

A 53 year old man with tricuspid regurgitation is undergoing a tricuspid valve repair. The heart is opened and the musculi pectinati are identified. Where are these structures located?

	A.	Right ventricle
	B.	Left ventricle
	C.	Right atrium
	D.	Pulmonary valve
	E.	Aortic valve

Answer 3

Right atrium
The musculi pectinati are found in the atria, hence the reason that the atrial walls in the right atrium are irregular anteriorly.
The musculi pectinati of the atria are internal muscular ridges on the anterolateral surface of the chambers and they are only present in the area derived from the embryological true atrium.

Question 4

A 33 year old man is stabbed in the right chest and undergoes a thoracotomy. The right lung is mobilised and the pulmonary ligament inspected. Which of the following structures does not lie within the pulmonary ligament of the right lung?

	A.	Pulmonary artery
	B.	Azygos vein
	C.	Pulmonary vein
	D.	Bronchus
	E.	None of the above

Answer 4

azygous
The pulmonary ligament is formed by a pleural condensation at the hilum of the lung. It encases the pulmonary vessels and trachea. The azygos vein is not contained within it.

Question 5

A 56 year old man requires long term parenteral nutrition and the decision is made to insert a PICC line for long term venous access. This is inserted into the basilic vein at the region of the elbow. As the catheter is advanced, into which venous structure is the tip of the catheter most likely to pass from the basilic vein?

	A.	Subclavian vein
	B.	Axillary vein
	C.	Posterior circumflex humeral vein
	D.	Cephalic vein
	E.	Superior vena cava

Answer 5

axillary vein
The basilic vein drains into the axillary vein and although PICC lines may end up in a variety of fascinating locations the axillary vein is usually the commonest site following from the basilic. The posterior circumflex humeral vein is encountered prior to the axillary vein. However, a PICC line is unlikely to enter this structure because of its angle of entry into the basilic vein.

Question 6

An individual is noted to have a left sided superior vena cava. By which pathway is blood from this system most likely to enter the heart?

A.	Via the coronary sinus
B.	Via the azygos venous system and into the superior vena cava
C.	Via anomalies in the pumonary vascular bed
D.	Via the left atrium and persistent foramen ovale
E.	Directly into the roof of the right atrium

Answer 6

coronary sinus
Persistent left superior vena cava is the most common anomaly of the thoracic venous system. It is prevalent in 0.3% of the population and is a benign entity of failed involution during embryogenesis.

Question 7

Which of the following structures is not located within the mediastinum?

	A.	Thymus
	B.	Heart
	C.	Great vessels
	D.	Arch of azygos vein
	E.	Vertebral bodies

Answer 7

The vertebral bodies lie outside of the mediastinum, as do the lungs.

Question 8

A 22 year old man is stabbed in the chest at the level of the junction between the sternum and manubrium. Which structure is at greatest risk?

	A.	Left atrium
	B.	Oesophagus
	C.	Thyroid gland
	D.	Inferior vena cava
	E.	Aortic arch

Answer 8

aortic arch
At the level of the Angle of Louis (Manubriosternal angle), is the surface marking for the aortic arch. The oesophagus is posteriorly located and at less risk.

Question 9

A 73 year old lady is admitted with brisk rectal bleeding. Despite attempts at resuscitation the bleeding proceeds to cause haemodynamic compromise. An upper GI endoscopy is normal. A mesenteric angiogram is performed and a contrast blush is seen in the region of the sigmoid colon. The radiologist decides to embolise the vessel supplying this area. At what spinal level does it leave the aorta?

	A.	L2
	B.	L1
	C.	L4
	D.	L3
	E.	T10

Answer 9

L3
The inferior mesenteric artery leaves the aorta at L3. It supplies the left colon and sigmoid. It’s proximal continuation to communicate with the middle colic artery is via the marginal artery.

Question 10

A 23 year old lady with troublesome axillary hyperhidrosis is undergoing a thorascopic sympathectomy to treat the condition. Which of the following structures will need to be divided to access the sympathetic trunk?

	A.	Intercostal vein
	B.	Intercostal artery
	C.	Parietal pleura
	D.	Visceral pleura
	E.	None of the above

Answer 10

Parietal pleura
The sympathetic chain lies posterior to the parietal pleura. During a thorascopic sympathetomy this structure will need to be divided. The intercostal vessels lie posteriorly. They may be damaged with troublesome bleeding but otherwise are best left alone as deliberate division will not improve surgical access.

Question 11

Secretion of saliva by the parotid gland is controlled by postsynaptic parasympathetic fibres originating in the inferior salivatory nucleus; these leave the brain via the tympanic nerve (branch of glossopharyngeal nerve (CN IX), travel through the tympanic plexus (located in the middle ear), and then form the lesser petrosal nerve until reaching the otic ganglion. After synapsing in the Otic ganglion, the postganglionic (postsynaptic) fibres travel as part of the auriculotemporal nerve (a branch of the mandibular nerve (V3) to reach the parotid gland.Ser

Answer 11

serosa
The oesophageal wall lacks the serosa layer

The wall lacks a serosa which can make the wall hold sutures less securely.

Question 12

Where is the ‘safe triangle’ for chest drain insertion located?

A.	4th intercostal space, mid axillary line
B.	5th intercostal space, mid axillary line
C.	4th intercostal space, mid scapular line
D.	5th intercostal space, mid scapular line
E.	4th intercostal space, mid clavicular line

Answer 12

‘Safe Triangle’ for chest drain insertion:

5th intercostal space, mid axillary line

Question 13

Your consultant decides to perform an open inguinal hernia repair under local anaesthesia. Which of the following dermatomal levels will require blockade?

	A.	T10
	B.	T12
	C.	T11
	D.	S1
	E.	S2

Answer 13

T12

Question 14

At which level does the aorta perforate the diaphragm?

	A.	T10
	B.	T9
	C.	T8
	D.	T11
	E.	T12

Answer 14

T12
Diaphragm aperture levels

Vena cava T8
Oesophagus T10
Aortic hiatus T12

Memory aid:
T8 (8 letters) = vena cava
T10 (10 letters) = oesophagus
T12 (12 letters) = aortic hiatus

Question 15

At which level is the hilum of the left kidney located?

	A.	L1
	B.	L2
	C.	T12
	D.	T11
	E.	L3

Answer 15

L1
Remember L1 ('left one') is the level of the hilum of the left kidney

Theme from April 2012 exam

This is commonly tested in the mrcs exam.

Question 16

You are assisting in an open right adrenalectomy for a large adrenal adenoma. The consultant is distracted and you helpfully pull the adrenal into the wound to improve the view. Unfortunately this is followed by brisk bleeding. The vessel responsible for this is most likely to be:

	A.	Portal vein
	B.	Phrenic vein
	C.	Right renal vein
	D.	Superior mesenteric vein
	E.	Inferior vena cava

Answer 16

IVC
It drains directly via a very short vessel. If the sutures are not carefully tied then it may be avulsed off the IVC. An injury best managed using a Satinsky clamp and a 6/0 prolene suture.

Question 17

A 63 year old man is undergoing a coronary artery bypass procedure. During the median sternotomy which structure would routinely require division?

	A.	Parietal pleura
	B.	Interclavicular ligament
	C.	Internal mammary artery
	D.	Brachiocephalic vein
	E.	Left vagus nerve

Answer 17

Interclavicular ligament

The interclavicular ligament lies at the upper end of a median sternotomy and is routinely divided to provide access. The pleural reflections are often encountered and should not be intentionally divided, if they are, then a chest drain will need to be inserted on the affected side as collections may then accumulate in the pleural cavity. Other structures encountered include the pectoralis major muscles, again if the incision is truly midline then these should not require formal division. The close relationship of the brachiocephalic vein should be borne in mind and it should be avoided, iatrogenic injury to this structure will result in considerable haemorrhage.

Question 18

A 34 year old male is being examined in the pre-operative assessment clinic. A murmur is identified in the 5th intercostal space just next to the left side of the sternum. From where is it most likely to have originated?

	A.	Mitral valve
	B.	Aortic valve
	C.	Pulmonary valve
	D.	Right ventricular aneurysm
	E.	Tricuspid valve

Answer 18

The tricuspid valve is generally referred to being best auscultated adjacent to the sternum. The plane of projected sound from the mitral area is best heard in the region of the cadiac apex.

Sites of auscultation
Valve Site
Pulmonary valve Left second intercostal space, at the upper sternal border
Aortic valve Right second intercostal space, at the upper sternal border
Mitral valve Left fifth intercostal space, just medial to mid clavicular line
Tricuspid valve Left fifth intercostal space, at the lower left sternal border

Question 19

During an Ivor Lewis Oesophagectomy for carcinoma of the lower third of the oesophagus which structure is divided to allow mobilisation of the oesophagus?

	A.	Vagus nerve
	B.	Azygos vein
	C.	Right inferior lobar bronchus
	D.	Phrenic nerve
	E.	Pericardiophrenic artery

Answer 19

The azygos vein is routinely divided during an oesophagectomy to allow mobilisation. It arches anteriorly to insert into the SVC on the right hand side.

Question 20

Which of the following statements relating to quadratus lumborum is false?

A.	Causes flexion of the thoracic spine
B.	Causes the rib cage to be pulled down
C.	Innervated by anterior primary rami of T12 and L1-3
D.	Attached to the iliac crest
E.	Inserts into the 12th rib

Answer 20

Causes flexion of the thoracic spine

The rectus abdominis causes flexion of the thoracic spine.

Attached to the medial iliac crest and iliolumbar ligament.
Inserts: 12th rib
Action: pulls the rib cage inferiorly. Lateral flexion.
Nerve supply: anterior primary rami of T12 and L1-3

Question 21

A 67 year old man is undergoing an angiogram for gastro intestinal bleeding. The radiologist advances the catheter into the coeliac axis. At what spinal level does this vessel typically arise from the aorta?

	A.	T10
	B.	L3
	C.	L4
	D.	T12
	E.	None of the above

Answer 21

T12

The coeliac axis lies at T12, it takes an almost horizontal angle off the aorta. It has three major branches.

Abdominal aortic branches

Branches Level Paired Type
Inferior phrenic T12 (Upper border)Yes. Parietal
Coeliac T12 No Visceral
Superior mesenteric L1 No Visceral
Middle suprarenal L1 Yes. Visceral
Renal L1-L2. Yes. Visceral
Gonadal L2 Yes. Visceral
Lumbar L1-L4. Yes. Parietal
Inferior mesenteric L3 No. Visceral
Median sacral L4 No. Parietal
Common iliac L4 Yes. Terminal

Question 22

At which of the following levels does the inferior vena cava exit the abdominal cavity?

	A.	T6
	B.	T7
	C.	T10
	D.	T8
	E.	T12

Answer 22

T8

Transpyloric plane
Level of the body of L1

Pylorus stomach
Left kidney hilum (L1- left one!)
Right hilum of the kidney (1.5cm lower than the left)
Fundus of the gallbladder
Neck of pancreas
Duodenojejunal flexure
Superior mesenteric artery
Portal vein
Left and right colic flexure
Root of the transverse mesocolon
2nd part of the duodenum
Upper part of conus medullaris
Spleen

Can be identified by asking the supine patient to sit up without using their arms. The plane is located where the lateral border of the rectus muscle crosses the costal margin.

Anatomical planes
Subcostal plane Lowest margin of 10th costal cartilage
Intercristal plane Level of body L4 (highest point of iliac crest)
Intertubercular plane Level of body L5

Common level landmarks
Inferior mesenteric artery	L3
Bifurcation of aorta into common iliac arteries	L4
Formation of IVC	L5 (union of common iliac veins)
Diaphragm apertures	
Vena cava T8
Oesophagus T10
Aortic hiatus T12

Question 23

Which of the positions listed below best describes the location of the coeliac plexus?

A.	Anterolateral to the aorta
B.	Posterolateral to the aorta
C.	Anterolateral to the sympathetic chain
D.	Anteromedial to the sympathetic chain
E.	Posterior to L1

Answer 23

Anterolateral to the aorta

The coeliac plexus us the largest of the autonomic plexuses. It is located on a level of the last thoracic and first lumbar vertebrae. It surrounds the coeliac axis and the SMA. It lies posterior to the stomach and the lesser sac. It lies anterior to the crura of the diaphragm and the aorta. The plexus and ganglia are joined are joined by the greater and lesser splanchnic nerves on both sides and branches from both the vagus and phrenic nerves.

Question 24

A patient has a chest drain insertion. There is fresh blood at the chest drain insertion area. Which vessel has been damaged?

	A.	Pericardiophrenic artery
	B.	Intercostal vein
	C.	Right ventricle
	D.	Vagus artery
	E.	Intercostal artery

Answer 24

Intercostal artery

Within the intercostal spaces there are thin, strong muscles, intercostal vessels, nerves and lymphatics. There are 3 intercostal muscle layers corresponding to the lateral abdominal wall; external, internal, innermost intercostals. At the mid axillary line there are thin intracostals which is an extension of the internal intercostal muscle. In each intercostal space lies the neurovascular bundle, comprising, from superior to inferiorly; the posterior intercostal vein, artery and nerve, lying protected in the subcostal groove of the rib above and situated between the second and third layer of the intercostal muscles. These blood vessels anastomose anteriorly with the anterior intercostal vessels, which arise from the internal thoracic artery and vein.

Question 25

A 56 year old lady is undergoing an adrenalectomy for Conns syndrome. During the operation the surgeon damages the middle adrenal artery and haemorrhage ensues. From which of the following structures does this vessel originate?

	A.	Aorta
	B.	Renal artery
	C.	Splenic artery
	D.	Coeliac axis
	E.	Superior mesenteric artery

Answer 25

Aorta

The middle adrenal artery is usually a branch of the aorta, the lower adrenal artery typically arises from the renal vessels.

Adrenal gland anatomy

Anatomy

Location Superomedially to the upper pole of each kidney
Relationships of the right adrenal Diaphragm-Posteriorly, Kidney-Inferiorly, Vena Cava-Medially, Hepato-renal pouch and bare area of the liver-Anteriorly
Relationships of the left adrenal Crus of the diaphragm-Postero- medially, Pancreas and splenic vessels-Inferiorly, Lesser sac and stomach-Anteriorly

Arterial supply Superior adrenal arteries- from inferior phrenic artery, Middle adrenal arteries - from aorta, Inferior adrenal arteries -from renal arteries
Venous drainage of the right adrenal Via one central vein directly into the IVC
Venous drainage of the left adrenal Via one central vein into the left renal vein

Question 26

A 22 year old man is undergoing an endotracheal intubation. Which of the following vertebral levels is consistent with the origin of the trachea?

	A.	C2
	B.	T1
	C.	C6
	D.	C4
	E.	C3

Answer 26

The trachea commences at C6. It terminates at the level of T5 (or T6 in tall subjects in deep inspiration).

Question 27

Which of the following pairings are incorrect?

A.	Aortic bifurcation and L4
B.	Transpyloric plane and L1
C.	Termination of dural sac and L4
D.	Oesophageal passage through diaphragm and T10
E.	Transition between pharynx and oesophagus at C6

Answer 27

Dural sac and L4

Vena cava T8 (eight letters)
Oesophagus T10 (ten letters)
Aortic hiatus T12 (twelve letters)

It terminates at S2, which is why it is safe to undertake an LP at L4/5 levels. The spinal cord itself terminates at L1.

Question 28

Which of the following is not considered a major branch of the descending thoracic aorta?

	A.	Bronchial artery
	B.	Mediastinal artery
	C.	Inferior thyroid artery
	D.	Posterior intercostal artery
	E.	Oesophageal artery

Answer 28

The inferior thyroid artery is usually derived from the thyrocervical trunk, a branch of the subclavian artery.

Thoracic aorta

Origin T4
Terminates T12
Relations
Anteriorly (from top to bottom)-root of the left lung, the pericardium, the oesophagus, and the diaphragm
Posteriorly-vertebral column, azygos vein
Right- hemiazygos veins, thoracic duct
Left- left pleura and lung
Branches
Lateral segmental branches: Posterior intercostal arteries
Lateral visceral: Bronchial arteries supply bronchial walls and lung excluding the alveoli
Midline branches: Oesophageal arteries

Question 29

What are the boundaries of the ‘safe triangle’ for chest drain insertion?

A.	Bounded by trapezius, latissimus dorsi, and laterally by the vertebral border of the scapula
B.	Bounded by latissimus dorsi, pectoralis major, line superior to the nipple and apex at the axilla
C.	Bounded by latissimus dorsi, serratus anterior, line superior to the nipple and apex at the axilla
D.	Bounded by trapezius, deltoid, rhomboid major and teres minor
E.	Bounded by trapezius, deltoid and latissimus dorsi

Answer 29

Bounded by latissimus dorsi, pectoralis major, line superior to the nipple and apex at the axill

There are a number of different indications for chest drain insertion. In general terms large bore chest drains are preferred for trauma and haemothorax drainage. Smaller diameter chest drains can be used for pneumothorax or pleural effusion drainage.

Insertion can be performed either using anatomical guidance or through ultrasound guidance. In the exam, the anatomical method is usually tested.

It is advised that chest drains are placed in the ‘safe triangle’. The triangle is located in the mid axillary line of the 5th intercostal space. It is bordered by:
Anterior edge latissimus dorsi, the lateral border of pectoralis major, a line superior to the horizontal level of the nipple, and the apex below the axilla.

Another triangle is situated behind the scapula. It is bounded above by the trapezius, below by the latissimus dorsi, and laterally by the vertebral border of the scapula; the floor is partly formed by the rhomboid major. If the scapula is drawn forward by folding the arms across the chest, and the trunk bent forward, parts of the sixth and seventh ribs and the interspace between them become subcutaneous and available for auscultation. The space is therefore known as the triangle of auscultation.

Question 30

Which of the following are not generally supplied by the right coronary artery?

	A.	The sino atrial node
	B.	The circumflex artery
	C.	The atrioventricular node
	D.	Most of the right ventricle
	E.	The right atrium

Answer 30

The circumflex artery is generally a branch of the left coronary artery.