Diaphragm Week 8 FINISHED

Question 1

What does the diaphragm consist of?

Answer 1

It is musculotendinous, and consists of both muscle and a central tendon, with the muscle peripherally and the tendon centrally

Question 2

Describe the central tendon of the diaphragm

Answer 2

A fibrous membrane that looks like three leaves (trefoil shaped). It is C-shaped like a boomerang.

Question 3

Describe the ‘leaves’ of the central tendon of the diaphragm

Answer 3

Right leaf = largest
Left leaf = smallest
Middle leaf = middle size

The anterior section of the middle leaf lies just inferior to the heart.

Question 4

What is the function of the diaphragm?

Answer 4

Mostly inspiration, however it does aid in increasing abdominal pressure, defecation, micturition,, parturition, and the valsalva manoeuvre

Question 5

What happens to the diaphragm during inspiration?

Answer 5

Central tendon descends, being pulled by the muscular part of the diaphragm peripherally.

Question 6

Why is the right dome of the diaphragm higher?

Answer 6

The liver

Question 7

How high does the right dome of the diaphragm reach?

Answer 7

As high as the 5th rib

Question 8

How high does the left dome of the diaphragm reach?

Answer 8

As high as the 5th intercostal space

Question 9

What dictates the level of the domes of the diaphragm?

Answer 9

Respiration phase, posture, size and degree of distension of abdominal viscera

Question 10

Describe the sternal part of the diaphragm. Is it always present?

Answer 10

Consists of 2 muscular slips which attach to the posterior aspect of the xiphoid process.

It is NOT always present

Question 11

Describe the costal part of the diaphragm. What part of the diaphragm does this part form?

Answer 11

Wide muscular slips that attach to the internal surfaces of the inferior 2 costal cartilages and adjoining ribs.

This part forms the domes of the diaphragm

Question 12

Describe the lumbar part of the diaphragm.

Answer 12

The medial and lateral arcuate ligaments are found in the lumbar part of the diaphragm, and form the right and left crura

Question 13

What are the medial and lateral arcuate ligaments?

Answer 13

They arise from 2 aponeurotic arches. They are thickenings of the fascia that cover QL and psoas major.

Question 14

Where does the medial arcuate ligament extend?

Answer 14

From the crus of the diaphragm to the TP of L1

Question 15

Where does the lateral arcuate ligament extend?

Answer 15

From the TP of L1 to rib 12

Question 16

How many crura does the diaphragm have?

Answer 16

2

Question 17

What does crus mean?

Answer 17

Leg like structure

Question 18

What are the diaphragmatic crura made of?

Answer 18

They are musculotendinous/ they are made of strong tendons

Question 19

Where do the diaphragmatic crura arise from?

Answer 19

The anterior surfaces of the upper three or four lumbar vertebra, anterior longitudinal ligament and IVD’s.

Question 20

Where does the right crus of the diaphragm arise from? Describe it in relation to the left.

Answer 20

• It is longer and larger than the left.

- It arises from the upper 3 or 4 lumbar vertebra.

Question 21

What does the right crus of the diaphragm form?

Why is this surprising?

Answer 21

It forms the oesophageal hiatus.

This is surprising because the hiatus is on the left.

Question 22

What does the left crus of the diaphragm arise from?

Answer 22

The upper 2 or 3 lumbar vertebra

Question 23

What is the function of the pericardiacophrenic ligaments

Answer 23

They fuse the central tendon of the diaphragm with the pericardium

Question 24

What are the 3 diaphragmatic apertures and at what level does each of them pass through the diaphragm?

Answer 24

Caval opening (IVC) = T8
Oesophageal hiatus = T10
Aortic hiatus = T12

Question 25

What does the caval foramen perforate to pass from the abdomen to the thorax and what does it permit the passage of?

Answer 25

It perforates the central tendon of the diaphragm to permit the passage of the IVC to the heart, as well as the terminal branches of the right phrenic nerve.

Question 26

Is the caval opening in the midline? What landmark on the diaphragm is it found at?

Answer 26

No it is found slightly to the right of the midline.

It is found at the junction of the right and middle leaves of the central tendon.

Question 27

Describe the facilitation of blood flow through the IVC via the action of the diaphragm

Answer 27

The IVC is firmly attached to the rise of the caval opening and as a result when the diaphragm contracts during inspiration the IVC is dilated. This facilitates blood flow through the vein.

Question 28

Within which crus of the diaphragm is the oesophageal hiatus found? What level of the spine is this hiatus?

Answer 28

It is found within the right crus, despite the hiatus being on the left of the midline. It is found at the level of T10

Question 29

What does the oesophageal hiatus transmit, apart from the oesophagus?

Answer 29

The anterior and posterior vagal trunks

The oesophageal branches of the left gastric vessels

Some lymph vessels

Question 30

What happens to the oesophagus when the diaphragm contracts and why?

Answer 30

A few muscle fibres of the right crus form a type of sphincter around the oesophagus which contracts when the diaphragm contracts. This prevents reflux of stomach contents into the oesophagus during inspiration from the increase in intraabdominal pressure.

Question 31

What is the aortic hiatus formed by?

Answer 31

The right the left crura and the fibrous median arcuate ligament. The arcuate ligament unites the right and left crus as an arch over the anterior aspect of the aorta.

Question 32

What does the aortic hiatus transmits and at what level is it?

Answer 32

Level of T12

Transmits the aorta, as well as the thoracic duct and sometimes the azygous vein

Question 33

What are some of the small openings in the diaphragm?

Answer 33

Sternocostal foramen/triangle:

• Found between the sternal and costal attachments of the diaphragm
• Transmits lymphatics vessels from the liver and the superior epigastric vessels

The sympathetic trunks pass deep to the medial arcuate ligament

Two small apertures in the crus of the diaphragm

• one transmits the greater splanchnic nerve
• the other the lesser splanchnic nerve

Question 34

What is the arterial supply to the diaphragm?

Answer 34

Superior surface:

• pericardiacophrenic and musculophrenic arteries
• branches of the internal thoracic artery (off subclavian artery)
• superior phrenic arteries (arise from the thoracic aorta)

Inferior surface:
- inferior phrenic arteries (typically arise from the abdominal aorta or may arise from the coeliac trunk)

Question 35

What is the venous drainage of the diaphragm?

Answer 35

Superior surface:
Pericardiacophrenic and musculophrenic veins
- drain into the internal thoracic veins
Superior phrenic vein (Rt side)
- drains into the IVC

Inferior surface:
Inferior phrenic veins
- Rt side typically drains into the IVC
- the Lt side is doubled with one draining into the IVC and the other into the suprarenal vein

Question 36

What is the innervation of the diaphragm?

Answer 36

Motor supply
Phrenic nerve (C3-5)
(C,3,4,5 keeps the diaphragm alive!!)
Each half of the diaphragm is supplied by its own phrenic nerve

Sensory supply
Centrally by the phrenic nerve C3-5
Peripherally - by the intercostal nerves (T5-11) & the subcostal nerves (T12)