Respiratory Anatomy

Question 1

What happens to our costal cartilage as we age?

Answer 1

As we age the costal cartilage becomes more ossified.

Question 2

What marks the inferior and superior thoracic apertures?

Answer 2

The costal margins border the inferior thoracic aperture whilst at the top of the rib cage the 1st ribs mark the superior thoracic aperture. Note the 1st rib is impalpable due to the clavicle.

Question 3

How do the ribs interact with the spine?

Answer 3

At the spine the ribs make 3 contact points – with the transverse process and with the spinal body of two adjacent vertebrae. Although this is not typical of all ribs.

Question 4

Which ribs aren’t in direct contact with the sternum?

Answer 4

Ribs 11 and 12 are floating and don’t attach to the sternum in any way. Ribs 7 to 10 are not in direct contact either but connect to costal cartilage that leads to the sternum.

Question 5

How do the ribs and sternum move to increase the volume of the thoracic cavity?

Answer 5

When we breathe in the ribs swing upwards like a bucket handle and thereby increasing the lateral diameter and therefore volume of the thoracic cavity. The sternum is also pushed outwards by the ribs pushing it forward.

Question 6

Where does the diaphragm lie anatomically and where can most of the muscle in the diaphragm be found?

Answer 6

Right dome of the diaphragm is very high due to the liver pushing it up higher (to about the 4th intercostal space) and on the left up to about the 5th intercostal space. Diaphragm is tendinous in the middle – most of the muscle is in the lateral sides.

Question 7

How far does the diaphragm move when we breath in?

Answer 7

When we breathe in the diaphragm moves down about 1.5 intercostal spaces.

Question 8

Other than the lungs and heart which two major organs are protected by the ribs?

Answer 8

The liver and the spleen although abdominal features sit behind the ribs on their respective sides due to the domed shape of the diaphragm.

Question 9

Describe the 3 layers of intercostal muscles

Answer 9

Intercostal muscles contain 3 layers – in the external layer the fibres move in a diagnal posto-anterior direction (external oblique), the internal muscles layer is also oblique and run perpendicular to the external layer finally the innermost intercostal are mostly found laterally on the thorax and run parallel to the internal layer.

Question 10

How do the internal and external intercostal muscles differ in function?

Answer 10

External muscle layer pulls the ribs upwards (only works becase the 1st rib is tethered). Internal intercostal muscles pull the ribs down. Internal intercostal muscles aren’t really used until you get out of breath.

Question 11

Where do the 3 tubes pass through the diaphragm?

Answer 11

Vena cava passes through the diaphragm at T8 and the oesophagus passes at T10 and finally the aortic hiatus is at T12.

Question 12

What are the accessory muscles?

Answer 12

Bending over when out of bredth – contract the pec to move the thorax to assist breathing.
In emphysema – use the neck muscles to move the chest wall and thorax a bit more. These are known as the accessory repsiratory muscles.

Question 13

Describe the neurovascular structures in the intercostal spaces

Answer 13

At the top of the intercostal muslces lies three neurovascular vessels: the intercostal vein, intercostal artery and intercostal nerve (in order from top to bottom. Whilst at the bottom of the rib intercostal space (top of the next rib) are collaterals of all three of the intercostal vessels mentioned earlier.

Question 14

What vascular structure supply the intercostal spaces with their blood?

Answer 14

For both these sets of vessels there are anterior and posterior versions that anastamose in the middle (laterally). The anterior intercostal artery and veins come from the internal thoracic artery and vein which also have anterior perforating cutenous branchescoming off at each level. At the posteriorside the posterior intercostal vein branches directly from the aorta whilst the veins come from the hemiazygos, accessory hemiazygos and the Azygos veins (which drains directly into the superior vena cava.

Question 15

What provides the nervous supply of the intercostal spaces?

Answer 15

The nerves however originates directly from the spine as the intercostal nerve and upon reaching the sternum becomes known as the anterior perforating branhces of the intercostal nerve, whilst at the back the lateral cutaneous branch of the intercostal nerve branches off early on and both feed cutaneous information for the dermatomes.

Question 16

Which nerves innervate the pericardium and diaphragm?

Answer 16

The phrenic nerves (C3, C4 and C5) supply the left and right lobes of the diaphragm. These pass across the heart and also supply the pericardium.

Question 17

What are the names of the lobes in each lung and what separates these lobes??

Answer 17

There are three lobes on the right lung – superior middle and inferior whilst on the left lung there is only a superior and inferior. These lobes are seperated by fissures, on the right the transverse fissure seperates the superior and middle lobes whilst the oblique fissue seperates the middle form the inferior and on the left lung the two lobes are seperated by the oblique fissure. The inferior lobes of both lungs occupy most of the back of the lungs.

Question 18

Why are you more likely to get a foreign object stuck in the right main bronchus than the left?

Answer 18

The right main bronchus sits at a much less acute angle than the left and so is much more likely to beocme obstructed by foreign objects.

Question 19

Where do the bronchi and vascular structure enter each lung?

Answer 19

When looking at the hilum of the lungs we can see that the airways enter posteriorly, the pulmonary veins leaves inferioranteriorly and the pulmonary arteries enter superanteriorly.

Question 20

What are the costodiaphragmatic recess and the costomediastinal recess?

Answer 20

The pleura of the lungs extends further than the lungs themselves when at rest and this space is called the costodiaphragmatic recess and allows the lung to expand downwards into the cavity when filling with air. There is also the costomediastinal recess around the heart.

Question 21

Discuss the blood supply to the lungs

Answer 21

Dual blood supply to the lungs via the pulmonary arteries and the bronchial arteries. Right bronchial artery comes from the right third posterior intercostal artery whilst there are two left bronchial arteries (posterior and inferior) both originating from different place on the aorta.