Lecture 14: Diaphragm

Question 0

What is the insertion of the diaphragm?

Answer 0

Converge into central tendon

Question 1

What is the origin of the diaphragm?

Answer 1

Thoracic outlet, xiphoid process, costal cartilages of ribs 6-12, L1-L3 vertebrae

Question 2

What is the motor Innervation to the diaphragm?

Answer 2

Right and left phrenic nerve (C3-C5 keeps the diaphragm alive)

Question 3

What is the sensory Innervation to the diaphragm?

Answer 3

Phrenic nerve = central
Intercostal nerve (T5-T11) = periphery

Question 4

Which dome is higher?

Answer 4

Right

Question 5

Purpose of crus in diaphragm?

Answer 5

Anchor diaphragm to lumbar vertebrae.

Question 6

What is the right crus and where does it arise from?

Answer 6

larger & longer, arises from sides of L1-L3 vertebral bodies and IV discs.

Question 7

What is the left crus and where does it arise from?

Answer 7

arises from sides of L1-L2 and IV disc.

Question 8

What does the Median arcuate ligament connect?

Answer 8

left and right crura

Question 9

Medial arcuate ligament covers what muscle?

Answer 9

thickening of fascia covering psoas major muscle

Question 10

Lateral arcuate ligament covers what?

Answer 10

thickening of fasica covering quadratus lumborum muscle.

Question 11

Caval opening at what level and what goes through it?

Answer 11

T8: Inferior vena cava and right phrenic nerve

Question 12

Oesophageal hiatus at what level and what goes through it?

Answer 12

@T10: oesophagus, right and left vagus nerves.

Question 13

Aortic hiatus at what level and what goes through it?

Answer 13

@T12: aorta, thoracic duct, azygos vein.

Question 14

Structures passing around the diaphragm

Answer 14

Greater and lesser splanchnic 
nerves (pass through crura on 
each side). 
• Hemiazygos vein (passes 
through left crus). 
• Least splanchnic nerves and 
sympathetic trunks (pass 
posterior to medial arcuate 
ligament). 
• Superior epigastric vessels 
(anterior to diaphragm, just 
deep to ribs).

Question 15

What is a Hiatal hernia?

Answer 15

Protrusion of the stomach into the thoracic cavity through a widening of the right crus of the diaphragm.

Question 16

During expiration the right and left dome reach what levels?

Answer 16

Right: 5th rib
Left: 5th intercostal space

Question 17

During inspiration the central tendon does what?

Answer 17

moves inferiorly and domes “flatten out”

Question 18

What occurs during inspiration?

Answer 18

Diaphragm contracts and lowers.

• Right crus contracts => compresses walls of oesophagus => prevents gastric contents being suctioned up with decrease in intra-thoracic pressure.
• Caval opening widens.

Question 19

Referred pain of diaphragm? Central region

Answer 19

Pain from the central region of the diaphragm will travel with visceral afferent fibres of the phrenic nerve and therefore be referred to skin of the supraclavicular C3,C4,C5 region.

Question 20

Referred pain of diaphragm? Peripheral region

Answer 20

Pain from the periphery of the diaphragm will
travel visceral afferent fibres of
intercostal nerves and be referred to the skin
over the costal margins of anterolateral
abdominal wall.

Question 21

Paralysis of diaphragm

Answer 21

• Crushing, sectioning or blocking phrenic nerve.

Question 22

Hiccups (Synchronous Diaphragmatic Flutter)

Answer 22

Sudden contraction of diaphragm and closure of
glottis pulls air rapidly through larynx causing
“hic” sound.
• Reflex arc (vagal afferents; phrenic & intercostal
efferents)

Question 23

Valsalva Manoeuvre

Answer 23

Increases intra-thoracic pressure which traps blood in 
great veins (impeding venous return) .when breath 
released Increased BF, increased HR, Increased BP => reflex bradycardia (decrease HR).

Question 24

What is the blood supply to the superior surface of the diaphragm?

Answer 24

Musculophrenic artery and vein branch of internal thoracic from subclavian

Question 25

What is the blood supply to the Inferior surface of the diaphragm?

Answer 25

Left and right Inferior phrenic vein and artery

Question 26

Which aperture is the weakest (most susceptible to widening)?

Answer 26

Oesophageal hiatus as it is going through muscle not tendon

Question 27

Fetal hiccups are important in strengthening and developing diaphragm, what happened without this?

Answer 27

Absence => pulmonary hypoplasia = death.

Question 28

The oesophageal hiatus is located in what structure?

Answer 28

Right crus

Question 29

The aortic hiatus is located in which structure?

Answer 29

Median arcuate ligament

Question 30

Why can sectioning the phrenic nerve help with tuberculosis?

Answer 30

If tuberculosis is in lower lobe of lungs, sectioning phrenic with make it a little more comfortable as lower lobe is leaning on diaphragm