Week 15 Anatomy - Thorax

Question 1

What forms the superior thoracic apeture?

Answer 1

Manubrium
1st Rib
1st thoracic vertebra

Question 2

What are the borders of the mediastinum? (Broadly, not the subdivisions)

Answer 2

Superior thoracic inlet - Superiorly
Mediastinal pleura - Laterally (parietal pleura of lungs)
Sternum and costal cartilages - Anteriorly
Vertebra - Posteriorly
Diaphragm - Inferiorly

Question 3

What are the subdivisions of the mediastinum?

Answer 3

Superior and inferior (further subdivided into the anterior, middle and posterior mediastinum)

Question 4

What are the borders of the superior mediastinum?

Answer 4

Superior thoracic inlet
Transverse thoracic plane (which is an axial slice at the level of T2/sternal angle, running to the inferior aspect of the endplate of T4)

Question 5

What major structures are transected by the transverse thoracic plane?

Answer 5

Carina
Aortic arch
Pulmonary trunk bifurcation

Question 6

Describe the subdivisions of the inferior mediastinum?

Answer 6

Anterior = anterior to the heart, between sternum and anterior heart (lymph nodes, blood vessels)

Middle = heart

Posterior = carina, oesophagus, sympathetic chain

Question 7

Outline the lobes of the right and left lungs:

Answer 7

R lung = 3 lobes, superior, middle and inferior lobe, with horizontal tissue separating the top two lobes, and oblique fissure inferiorly

L lung = 2 lobes, superior and inferior lobes, separated by an oblique fissure.

Question 8

At the hilum, describe the orientation of the pulmonary arteries, veins, and bronchi:

Answer 8

Superiorly = arteries, as they come superiorly off out of the RA

Inferiorly = pulmonary veins, coming back to the LA

Posteriorly = bronchi

Question 9

What is the point where the visceral pleura folds on itself and becomes the parietal pleura?

Answer 9

Pulmonary ligament - at the hilum, leaving the root of the lung uncovered and allowing structures to pass between the heart/airway and the lung

Question 10

What are the openings in the diaphragm?

Answer 10

Oesophageal hiatus - posterior and to the left
Caval hiatus - anterior and to the right
Aortic hiatus - not a proper hole in the diaphragm, rather posterior to diaphragm

Question 11

What level does the oesophagus pass through diaphragm? What travels with it?

Answer 11

T10
Anterior and posterior vagal trunks

Question 12

What level does the IVC pass through diaphragm? What travels with it?

Answer 12

T8
terminal branches of phrenic nerve

Question 13

What level does the aorta pass through diaphragm? What travels with it?

Answer 13

T-12
Thoracic duct
Azygous veins

Question 14

What are ‘the typical ribs’?

Answer 14

Ribs 2-10

Question 15

What are the atypical ribs?

Answer 15

1, 11 and 12

Question 16

What type of joint is a cost-vertebral joint?

Answer 16

Synovial joint

Question 17

Describe layers of the intercostal space:

Answer 17

Skin
Superficial fascia
Subcutaneous tissue
External intercostals (infero-anteriorly)
Internal intercostals (infero-posteriorly)
Innermost intercostals (Infero-posteriorly)
Endothoracic fascia
Parietal pleura

Question 18

What is the function of the transverse thoracis?

What is it’s location/attachment?

Answer 18

Weakly depress the ribs

From costal cartilages ribs 2-6, to posterior aspect of sternum

Question 19

Between what layer of the chest wall does the neurovascular bundle run?

Answer 19

Between internal and innermost intercostal muscles, in the costal groove

Question 20

What the order of the neurovascular bundle from superior to inferior? (All are ‘intercostal’)

Answer 20

VAN

Vein
Artery
Nerve

Question 21

What is the thoracic duct, and it’s function?

Answer 21

45cm lymphatic vessel which drains all lymph from below the diaphragm, as well as the left upper limb

Question 22

How is the thoracic duct formed, and what course does it follow?

Answer 22

Formed by merging of lymphatic trunks of lower limbs T12 (cisterns chyli) and ascends into the thorax, adjacent to the aorta, azygous vein (anterior to the vertebrae) and crosses the midline toward the left at T5.

Drains into the subclavian vein.

Question 23

What are the contents of the superior thoracic inlet in the midline, from anterior to posterior?

Answer 23

Sternohyoid and sternothyroid muscles
Thymic remnants
Inferior thyroid veins
Trachea
Recurrent laryngeal nerve
Oesophagus
Thoracic duct
Longus colli muscles
Anterior longitudinal ligament

Question 24

What are the landmarks for an intercostal catheter?

Answer 24

Superior = base of axilla
Inferior = 5th intercostal space, midaxillary line (approx line off the nipple)
Medial = lateral edge of pectoralis major
Lateral = lateral edge of latissimus dorsi

Question 25

What is “the triangle of safety”?

Answer 25

Anteriorly = pec major
Posteriorly = lat dorsi
Inferiorly = 5th ICS

Question 26

What cranial nerves pass anterior and posterior to the root of the lung?

Answer 26

Phrenic nerve passes anteriorly
Vagus nerve passes posteriorly

Question 27

What supplies blood to the pleura?

Answer 27

Intercostal arteries + bronchial arteries

Question 28

What layer of the pleura has pain innervation?

Answer 28

Parietal

Question 29

What are the different pleural surfaces (which then contribute to pleural reflections)?

Answer 29

Costal
Diaphragmatic
Mediastinal

Question 30

What are the pleural reflections? How many are there?

Answer 30

Discrete change in direction of PARIETAL pleura.
There are 3 major/common types.

Question 31

Describe the different pleural reflections:

Answer 31

1. Vertebral reflection (posteriorly, formed by folding of costal pleura as it reaches the vertebral column and then travels anteriorly
2. Sternal reflection (anteriorly, formed by folding of mediastinal pleura as it encounters anterior chest wall and travels laterally
3. Costal reflection (is the line along which the costal pleura and diaphragmatic pleura surfaces merge)

Question 32

Describe the course of the vagus nerve in the thorax.

Answer 32

Originate from medulla
Leaves cranium via jugular foramen
Travels with internal jugular vein and internal carotid artery within carotid sheath
Passes through superior thoracic aperture (which is where left and right vagus nerve paths slightly differ)

From here, the vagus nerve wants to get to the oesophagus

LEFT Vagus travels over/around aortic arch to then run down oesophagus

RIGHT vagus nerve transitions from the common carotid onto the oesophagus

**It will form cardiac and pulmonary plexus to provide parasympathetic innervation and then rejoin as a single nerve before descending with oesophagus through diaphragmatic hiatus into the abdomen

Question 33

Describe the course of the phrenic nerve in the thorax:

Answer 33

Originates from spinal nerves C3-C5 (predominantly C4)

Pops up between anterior and middle scalene muscles, and travels along anterior surface of anterior scalene, where it encounters the subclavian vein. It passes posterior to subclavian vein, but anterior to subclavian artery.

Travels into thorax between mediastinal pleural and fibrous pericardium, and travels ANTERIOR to the structures of the root of the lung.

LEFT phrenic nerve travels through canal hiatus, and RIGHT phrenic nerve directly pierces diaphragm to innervate from inferior surface.

N.B. In the neck, the phrenic nerve is lateral to the vagus nerve, because, schizoPHRENIC people are on the periphery/lateral margins of society.