Week 1: Thoracic Anatomy

Question 1

Which are the true ribs?

Answer 1

1-7

Question 2

Which are the false ribs?

Answer 2

8-10

Question 3

Which are the floating ribs?

Answer 3

11-12

Question 4

Which tissue do the thoracic cage and wall refer to respectively?

Answer 4

cage: skeletal wall: muscular

Question 5

Which structures pass through the inferior thoracic aperture? Also think of the level of passage through the diaphragm

Answer 5

• oesophagus (T10 - level of passage through diaphragm) - aorta (T12 - level of passage through diaphragm) - inferior vena cava (T8 - level of passage through diaphragm) - thoracic duct - azygous vein - phrenic nerve

Question 6

At what level are the oesophageal and aortic hiatus respectively?

Answer 6

T10 and T12

Question 7

Name 4 functions of the thoracic cage

Answer 7

• protect throacic organs - protect abdominal organs - provide attachment for muscles - support the weight of the upper limbs

Question 8

Name the components of the thoracic cage

Answer 8

• thoracic vertebrae - intervertebral discs - ribs - sternum - costal cartilages

Question 9

What cartilage type makes up the costal cartilage?

Answer 9

hyaline

Question 10

How many ribs are there in total?

Answer 10

12

Question 11

In which ways does the thoracic cage expand (3)?

Answer 11

• Ribs elevate and flare out (transverse plane increase) - Sternum and distal ribs elevate and move anteriorly (sagittal plane) - Diaphragm contracts and moves inferiorly (coronal plane)

Question 12

How does Boyle’s Law explain inspiration through an increase in the thoracic space

Answer 12

The increase in volume is inversely proportional to the air pressure. This means an increase in volume decreases the pressure and creates a negative pressure compared to atmospheric air. This negative pressure causes air to move into the lungs

Question 13

To which structures does the diaphragm attach

Answer 13

Xiphoid process - Costal margin - Lateral floating ribs - T12 - Central tendon (insertion)

Question 14

Which 3 main structures pass through the diaphragm?

Answer 14

• IVC (level T8) - oesophagus (Level T10) - aorta (Level T12)

Question 15

What is the nervous spply of the diaphragm? (nerve+roots)

Answer 15

phrenic nerve via anterior rami of C3,4,5

Question 16

Describe the external intercostal muscle (activity, fibre direction)

Answer 16

Fibres run inferio-medially - Active during inspiration

Question 17

Describe the internal intercostal muscle (activity, fibre direction)

Answer 17

• Fibres run inferiolaterally - Active during expiration

Question 18

Where do the intercostal muscles originate and insert?

Answer 18

They attach at the inferior border of the superior rib and the superior border of the inferior rib

Question 19

Name the accessory muscles to inspiration

Answer 19

• Scalenes - Sternocleidomastoid - pectoralis major - pectoralis minor - serratus anterior - serratus posterior - levator costarum

Question 20

What is the neurovascular supply of the intercostal space?

Answer 20

One large, major neurovascular bundle underlying the rib and one collateral neurovascular bundle just superior to the lower rib

Question 21

Where do neurovascular bundles run in the intercostal space?

Answer 21

Under each rib in the costal groove between the internal and the innermost intercostal muscle

Question 22

In which order do the vessels and nerve in the neruovascular bundle travel from superior to inferior?

Answer 22

Vein -> artery -> nerve

Question 23

What is the advantage of having the vein, artery, and nerve ordered in the way that they are?

Answer 23

The vein is most susceptible to bleeding out of the vessels so it is most protected superiorly. The artery is better designed to constrict to reduce blood loss. The nerve is least protected, as branches from separate nerves overlap and supply the skin overlying the rib even if one nerve is damaged.

Question 24

Which larger arteries supply the intercostal arteries posteriorly?

Answer 24

Posteriorly-Superiorly (Rib 1+2): the subclavian via the costocervical branch and supreme intercostal artery. Posteriorly-Inferiorly: the aorta

Question 25

Which larger arteries supply the intercostal arteries anteriorly?

Answer 25

Anteriorly: the internal thoracic artery from the subclavian until the 6th rib where internal thoracic divides into the superior epigastric and the musculophrenic arteries. From this level the intercostal space is supplied by the musculophrenic artery

Question 26

What the gender-based difference in vasculature in the intercostal blood supply?

Answer 26

the 2nd to 5th anterior intercostal arteries are larger in females to supply the breasts. All other intercostal arteries are smaller in females than in males

Question 27

Where do the intercostal veins drain posteriorly?

Answer 27

The azygous system of veins: on the right into the azygous vein. On the left into brachiocephalic vein (Rib 1-3) the hemiazygous vein (Rib 4-8) and accessory hemiazygous vein (Rib 9-12) The hemiazygous and its accessory both drain into the azygous which then drains into the SVC

Question 28

Where do the intercostal veins drain anteriorly?

Answer 28

The internal thoracic veins which drain into the brachiocephalic veins

Question 29

Describe the course and branches of the intercostal nerve

Answer 29

The intercostal nerve arises from the anterior ramus. It travels in the costal groove. The nerve branches superficially to give rise to the lateral cutaneous nerve and anteriorly to give rise to the anterior cutaneous nerve.

Question 30

Comment on intercostal nerve overlap

Answer 30

The intercostal nerves overlap with branches from the same side superiorly and inferiorly, but there is little overlap between the right and left side of the body past the midline

Question 31

Describe the lymphatic drainage of the thorax and its venous destination

Answer 31

The lymphatic drainage is via the parasternal nodes, the intercostal nodes and diaphragmatic nodes. These drain into the thoracic duct which drains into the left brachiocephalic vein

Question 32

Where would you enter a chest drain?

Answer 32

At the intersection of a line from the 5th intercostal space (nipple-line) and the mid-axillary line, above a rib (as to sacrific collateral branches rather than intercostal neurovasculature

Question 33

Which nerves supply the thoracic wall?

Answer 33

2nd-6th intercostal nerves

Question 34

Which nerves supply the abdominal skin and muscles?

Answer 34

7th-11th intercostal nerves

Question 35

What superficial area is supplied by the subcostal nerve?

Answer 35

The anterior inferior abdominal wall

Question 36

Fill the blanks and add which other structures pass through the superior thoracic aperture (10 in total)

Answer 36

1. oesophagus 2. right common carotid 3. trachea 4. internal jugular vein (passes through via brachiocephalic) 5. apex of lung 6+7. (right) subclavian artery and vein 8. brachiocephalic artery 9. brachiocephalic veins 10. vagus nerve 11. phrenic nerve

Question 37

Fill the blanks

Answer 37

1. IVC 2. oesophagus 3. aorta 4. central tendon of diaphragm 5. aortic hiatus 6. oesophageal hiatus

Question 38

fill the blanks

Answer 38

1. Manubrium 2. Body of sternum 3. Xiphoid process 4. sternal angle (aka manubriosternal joint) 5. jugular notch 6. transverse ridges 7. articular surface for clavicle 8. articular surface for rib 1 9. articular demifacets for rib 2 10. articular facets for ribs 3-6 11. articular facet for rib 7

Question 39

Fill the blanks

Answer 39

1. Head 2. Neck 3. Shaft 4. Tubercle 5. Costal groove

Question 40

Fill the blanks

Answer 40

1. External intercostal muscle 2. Internal intercostal muscle 3. Innermost intercostal muscle 4. External intercostal membrane