Lecture 8

Question 1

Describe the diaphragm?

Answer 1

Muscular base of the thorax with two muscular domes. 1 on the left and one on the right. The right one sits higher due to the liver sitting on the right.

Question 2

What occurs when the diaphragm moves up and down?

Answer 2

As the diaphragm moves up and down the pressure inside the volume box will change. As a muscle

Question 3

What happens when the diaphragm contracts?

Answer 3

It descends inferiorly. This aids in ventilation. Allows you to inspire and pushing down into the abdomen, which increases abdomen pressure and helps with venous return to the heart.

Question 4

Describe the ligaments on the posterior side of the diaphragm?

Answer 4

Ligaments. Right centrally is the median arcuate ligament. Immediately lateral to the median is a pair of ligaments called the medial arcuate ligaments. Coming out further laterally is the lateral arcuate ligaments.

Question 5

Where does the IVC pass through the diaphragm (level wise)?

Answer 5

T8.

Question 6

Where does the oesophagus pass through the diaphragm (level wise)?

Answer 6

T10.

Question 7

Where does the aorta through the diaphragm (level wise)?

Answer 7

T12.

Question 8

Where does the phrenic nerve come from?

Answer 8

Somatic nerve that comes from the neck and supplies the diaphragm from underneath.

Question 9

Describe the crura of the diaphragm?

Answer 9

The right crus comes around further and comes bit onto the left hand side. Where the fibres meet is called the central tendon of the diaphragm (white tendinous region).

Question 10

What passes through the central tendon?

Answer 10

IVC (@T8). A tendon hasn’t got a lot of contractility, the IVC won’t get compressed as the diaphragm contracts and descends. The right phrenic nerve goes through the same opening and spreads out in a radial fashion and supplies RHS of diaphragm.

Question 11

Describe the left phrenic nerve?

Answer 11

Comes directly through the left crus of the diaphragm.

Question 12

Describe the right crus of the diaphragm int arms of the oesophagus?

Answer 12

The oesophagus comes through the right crus (forms sling around oesophagus and acts like a sphincter - so oesophagus stays closed most of the time). It will come through with the vagus nerve (parasympathetic supply) - surround oesophagus as a plexus as ant and post vagal trunks.

Question 13

Where does the aorta come through?

Answer 13

Behind the median arcuate ligament, so that the aorta can’t be compressed and flow posteriorly.

Question 14

Where does the thoracic duct come through?

Answer 14

Comes through next to the aorta.

Question 15

What comes underneath the medial arcuate ligament?

Answer 15

Psoas major muscle and lateral to it is quadratus lumborum.

Question 16

Describe the phrenic nerve?

Answer 16

Made up of fibres form C3-C5. It is a somatic nerve and under your control and some overriding autonomic control. Gives fibres off to the pericardium and pierces through the diaphragm.

Question 17

What is referred pain?

Answer 17

Feel it as a pain different to anatomical position of pain origin.

Question 18

What happens if the phrenic nerve gets irritated?

Answer 18

In the shoulder. The pain is coming form something intra-abdominal i.e. pancreatitis.

Question 19

What are somatic nerves?

Answer 19

Nerves that you can control e.g. peripheral nerves (intercostal nerves and the phrenic nerve).

Question 20

What are autonomic nerves?

Answer 20

Nerves tha you can’t control (visceral).

Question 21

What can the autonomic nervous system be divided into?

Answer 21

Parasympathetic and sympathetic nervous system.

Question 22

Describe the PNS?

Answer 22

PNS exists in two places - brains stem and sacral part of spinal cord.
Cranial Nerve X - Vagus nerve.
Causes decreases in Heart Rate (HR) and Cardiac Output (CO) and causes constriction of bronchioles.

Question 23

Describe the SNS?

Answer 23

Find these nerves from T1-L2.
T1-T5: sympathetic to cardiac and pulmonary plexuses.
T6-L2: splanchnic nerve.
Sympathetic chain.
Relaxes bronchioles and increases HR and CO.

Question 24

Describe sympathetic chains?

Answer 24

This is the only place that sympathetic supply comes from. Any interruption to the nerves can give you symptoms and signs in other places; due to all sympathetic supply coming form the thorax.

Question 25

What occurs during a mediastinal tumour when the phrenic nerve is damaged?

Answer 25

[If there are sternal wires then the chest has been opened up.]
When the diaphragm has lost its nerve supply it cannot contract, thus the side that has lost its nerve supply the diaphragm stays up.

Question 26

Describe Horner’s Syndrome?

Answer 26

When a patient has the classical symptoms:
1. Ptosis - eyelid droops (control to eyelid has been lost).
2. Miosis - pupil constriction (an eyelid that is hanging halfway done and one that is not reactive to light).
3. Anhydrosis - lack of sweating, one half of face will be very dry.
Could be a first sign that a person has a tumour in their chest as it is stopping the flow up into the face and neck.