Respiratory: Anatomy - Diaphragm

Question 1

Describe the structure of the diaphragm

Answer 1

Double-domed musculotendinous sheet with central tendon

Question 2

What is the effect of paralysis of the diaphragm on breathing?

Answer 2

Paradoxical movement (diaphragm is raised during inspiration, depressed during expiration)

Question 3

Describe the peripheral attachments of the costal, sternal and lumbar parts of the diaphragm

Answer 3

Costal: costal cartilages ribs 7-10, direct to ribs 11-12
Sternal: xyphoid process
Lumbar: lumbar vertebrate and arcuate ligaments (R crus L1-3, L crus L1-2)

Question 4

Describe the central attachment of the diaphragm

Answer 4

Via central tendon which infuses with inferior pericardium and is perforated by caval opening

Question 5

Describe the motor and sensory innervation of the diaphragm

Answer 5

Motor: phrenic nerve (C3-5)
Sensory: phrenic nerve (C3-5) centrally, intercostal (T5-11) and subcostal (T12) nerves peripherally

Question 6

Describe the arterial, venous and lymphatic supply/drainage of the diaphragm

Answer 6

Arterial: superior phrenic, musculophrenic and pericardiophrenic to superior surface; inferior phrenic to inferior surface
Venous: as per arterial for superior surface (superior phrenic drains to IVC, others to internal thoracic); R inferior phrenic (to IVC) and L inferior phrenic (to IVC and suprarenal)
Lymphatics: superior surface to mediastinal nodes, inferior surface to superior lumbar nodes

Question 7

What is the effect of diaphragm contraction on venous return?

Answer 7

Increases due to reduction in intrathoracic pressure

Question 7

Describe the actions of the diaphragm

Answer 7

Contracts and flattens in inspiration to increase thoracic volume and decrease intrathoracic pressure

Question 8

How high can the diaphragm ascend when relaxed?

Answer 8

Up to level of 5th rib/intercostal space

Question 9

Describe the three openings of the diaphragm: their levels, contents and location

Answer 9

Caval opening in central tendon at level of C8: IVC, R phrenic nerve and lymphatics
Oesophageal hiatus in R crus at level of C10: oesophagus, vagal trunks, oesophageal branches of L gastric vessels, and lymphatics
Aortic hiatus between crura posterior to median arcuate ligament: aorta, thoracic duct, azygous and hemiazygous veins

VENA CAVA = 8 letters (T8)
OESOPHAGUS = 10 letters (T10)
AORTIC HIATUS = 12 letters (T12)

Question 10

Describe the location/course of the three arcuate ligaments

Answer 10

Median: unites crura anterior to aorta, forms aortic hiatus
Medial: fascial thickening over psoas major, attached to lumbar vertebral bodies and L1 transverse processes
Lateral: covers quadratus lumborum

Question 11

What is median arcuate ligament syndrome?

Answer 11

Syndrome in which the median arcuate ligaments lies anterior to coeliac trunk rather than superior
Causes compression of coeliac trunk presenting as abdominal pain (thought to be due to abdominal organ ischaemia or compression of coeliac ganglia)