Lecture 14: Diaphragm and nerves of the thorax

Question 1

In relation to the thorax, what does the diaphragm represent?

Answer 1

Inferior thoracic aperture

Question 2

Is the diaphragm continuous?

Answer 2

No, it is discontinuous and jumps between certain places but in a highly functional manner

Question 3

What are the ligaments of the diaphragm?

Answer 3

Arcuate ligaments: - Median: L&R crura - Medial: Crus-L1 TP (Psoas major) - Lateral: L1 TP - R12 (Quad lumborum)

Question 4

What are the openings of the diaphragm:

Answer 4

• Caval = T8 - Oesophageal = T10 - Aortic = T12

Question 5

Describe the diaphragm features using the 8,10,12 rule;

Answer 5

T8: IVC + R. Phrenic T10: Oesophagus + Vagal trunks T12: Aorta + Azygous + Thoracic duct

Question 6

What are the first major paired of arteries off the abdominal aorta?

Answer 6

Inferior phrenic artery

Question 7

What are some arteries that supply the diaphragm?

Answer 7

• Inferior phrenic (abdo aorta) - Superior phrenic (lower thoracic aorta) - Musculophrenic (internal thoracic) - Pericardiacophrenic (internal thoracic) - Intercostal arteries (small branches) Dont specifically need to know

Question 8

What are some notes on the phrenic nerve:

Answer 8

• C3-5 keep the diaphragm alive - Give off pericardial branches - LHS courses further out from midline b/c of heart orientation

Question 9

What sort of fibres are the phrenic nerve and where do they come off the spine?

Answer 9

• C3-5 come off anterior rami - Motor/sensory/sympathetic fibres (sensory to central tendons)

Question 10

Describe the course of the phrenic nerve:

Answer 10

• Run obliquely anterior surface of ant. scalene muscle into thoracic cavity - Pass between subclavian arteries and veins into thorax - Pass anterior to hila of the lungs

Question 11

Describe intercostal vessels;

Answer 11

VAN Vein Artery Nerve (Travel under the inferior facet of the rib)

Question 12

Describe the sympathetic innervation of the body:

Answer 12

sympathetic nerves are generated at T1-L1/2, but they join the sympathetic chain which extends to all vertebral levels

Question 13

On the symp. chain where are grey and white rami located?

Answer 13

White rami = T1-L1/2 symp. output to chain (myelinated) Grey rami = All levels from chain to spinal nerve

Question 14

Does the ANS have afferent and efferent fibres? if so describe

Answer 14

Yes Efferent = Effecting change, travels through dorsal root Afferent = Efferent out through ventral root

Question 15

What is a splachnic nerve?

Answer 15

Nerve that comes off the the chain ganglion to a plexus and then on to the viscera

Question 16

What are the thoracic splanchnic nerves?

Answer 16

• Cardiopulmonary (T1-4) (cardiac and pulmonary plexuses) - Greater (T5-9) (coeliac plexus) - Lesser (T10-11) (Superior mesenteric plexus) - Least (T12) (Aorticorenal plexus)

Question 17

What is the plexus, symp and parasymp of the foregut?

Answer 17

Plexus: Celiac Symp: Greater splanchnic (T5-T9) Parasymp: Vagus

Question 18

What is the plexus, symp and parasymp of the midgut?

Answer 18

Plexus: Sup mesenteric Symp: Lesser splanchnic (T10-T11) Parasymp: Vagus

Question 19

What is the plexus, symp and parasymp of the aorticorenal region?

Answer 19

Plexus: Renal Symp: Least splanchnic (T12) Parasymp: Vagus

Question 20

Whats notable about the ANS fibres in the thorax?

Answer 20

Either down or across except for the diagonal splanchnic

Question 21

Describe referred pain:

Answer 21

Brain interprets pain as from the somatic spinal segment i.e the body wall not the viscera = referred pain i.e organ pain is interpreted as coming from somatic body wall pain. Sooo if it goes up symp. trunk where it goes into the vertebrae determines the referred pain area.

Question 22

Where is phrenic nerve pain referred to?

Answer 22

C3-5 dermatome as a mixture of ANS and somatic nerves in the diaphragm. Weird one.

Question 23

Answer 23

Question 24

Answer 24

Question 25

Answer 25

Question 26

Answer 26