Lecture 4 DA

Question 1

Where do all diaphragmatic fibres attach?

Answer 1

To the central tendon.

Question 2

Describe the positions of the two diaphragmatic domes relative to each other, and why they are so.

Answer 2

Right dome is higher due to the liver.Left dome is lower due to the apex of the heart.

Question 3

Where does the diaphragm insert into?

Answer 3

The xyphoid process directly.Costal margin via the inferior 6 ribs and their costal cartilage.Lumbar vertebra via the left crus (L1-L2/3) and right crus (L1-L3/4).

Question 4

What are the 3 ligaments of the diaphragm, and where are they positioned?

Answer 4

Medial arcuate ligament - over psoas major muscle.Lateral arcuate ligament - over quadratus lumborum muscle.Median arcuate ligament - between the left and right crura.

Question 5

What are the three openings in the diaphragm, what passes through them, and at what spinal level are they found?

Answer 5

Caval opening (T8) - Inferior vena cava, in the central tendon.Oesophageal hiatus (T10) - Formed as the left crus slings over (hairpin-like). Is within diaphragmatic fibres.Aortic hiatus - Descending/thoracic aorta. Also within diaphragmatic fibres.

Question 6

How does diaphragmatic contractions aid in blood movement?

Answer 6

When the diaphragm contracts, given its location within the central tendon, it will be pulled outward by it, reducing pressure within and creating suction, aiding blood flow to the heart.

Question 7

What role does the left crus play in the oesophageal hiatus?

Answer 7

As the left crus is slung around the oesophagus, diaphragmatic contraction will close the hiatus, preventing reflux during breathing when pressure within the thoracic/abdominal cavity increases.

Question 8

What structures do the left and right phrenic nerve pierce?

Answer 8

The right phrenic nerve pierces the central tendon, while the left pierces the peripheral muscles.

Question 9

Where are the azygous and hemiazygous veins positioned relative to the aorta?

Answer 9

Azygous - right side.
Accessory hemiazygous - left side, ribs 4-7.
Hemiazygous - left side, ribs 9-11.

Question 10

What supplies nerve innervation to the diaphragm?

Answer 10

Phrenic nerve supplies mostly sensory innervation to the central tendon (right phrenic nerve) the peripheral muscles (left phrenic). It also supplies all motor to the diaphragm.Note - lower intercostal nerves provide sensory innervation to the periphery of the diaphragm.

Question 11

Where do the two phrenic nerves project relative to the root of the lung?

Answer 11

They are both anterior to the root of their respective lung.

Question 12

To which dermatomes do the following structures refer pain to?
Central tendon
Peripheral muscles

Answer 12

Central tendon - C3-5

Peripheral muscles - thoracic wall dermatomes.

Question 13

What does breathing depend on?

Answer 13

Creating a pressure differential, lower within the lungs to breathe in, and higher within to breathe out. Equal pressure means to net movement of air.

Question 14

If volume within the lungs increases, what happens?

Answer 14

Pressure decreases, and you breathe in. Diaphragm must contract.

Question 15

If pressure within the lungs increases, what happens?

Answer 15

Volume must have decreased, and you breathe out. Diaphragm must relax.

Question 16

What is the parietal pleura attached to?

Answer 16

Thoracic wall.

Question 17

What is found within the pleural cavity, and what purpose does it serve?

Answer 17

Pleural fluid. It acts as a lubricant, and creates negative pressure using surface tension. It allows the visceral pleura (and consequently, the lungs) to expand and depress with the thoracic cage.

Question 18

Breathing is a rythmic contraction. What structure is responsible for it?

Answer 18

The brain stem.

Question 19

Describe pump handle movement.

Answer 19

During elevation when breathing, the sternum moves anterosuperiorly. This is due to the shape of the 2nd - 6th ribs. It increases anterior-posterior dimension.

Question 20

Describe bucket handle movement.

Answer 20

During elevation when breathing, the 7th - 10th ribs move outward transversely, increasing the transverse diameter.

Question 21

Describe the actions of the following muscles.
Scalene muscle
Abdominal muscle
Medial & lateral intercostal muscles
External  intercostal muscle

Answer 21

Scalene - elevates the 1st & 2nd ribs, expanding thoracic cavity.
Abdominal - Depresses thoracic cavity.
Medial internal intercostal - Expands thoracic cavity.
Lateral internal intercostal - Depresses thoracic cavity.
External intercostal - Expands thoracic cavity.

Question 22

What seperates the medial and lateral internal intercostal muscle?

Answer 22

Costochondral junction.Note - they are both one single muscle, but are functionally different.

Question 23

What happens during hiccups, and name 3 possible causes.

Answer 23

Quick inspiration from spasmic contraction of the diaphragm.1. Irritation of the phrenic nerve.2. Brain stem respiratory centre (not center. Centre has no oil in it, no need to invade, calm down).3. Diaphragm istelf.

Question 24

Where are breast implants commonly placed in a plastic surgery?

Answer 24

1. Retromammary space. Makes it difficult to find breast cancer after a mammogram. Looks less natural.2. Behind pectoralis major. Looks more natural.3. Combination of the two.

Question 25

What can be found in a lobule within a breast? How many lobules does a breast have?

Answer 25

Each lobule has a secreting alveolus. A breast has 15-20 lobules.

Question 26

What are lobules drained by?

Answer 26

A lactiferous duct. Each of these merge at the nipple.

Question 27

What is the lactiferous sinus?

Answer 27

A small cavity at the nipple the stores some milk when a mother is lactating. When a baby tries to suck, it releases some milk to stimulate it to try and catch on.

Question 28

What are suspensory ligaments?

Answer 28

Ligaments that have a skin to lobule connection to keep things in place.

Question 29

What structures does the breast overlay?

Answer 29

1/3rd of the serratus anterior, and ribs 2-6.

Question 30

What is the axillary tail, and what is it often mistaken for?

Answer 30

An area of breast tissue (Superior and lateral most) that can look like a lump and be palpated. Is often mistaken for a tumour or swollen lymph node.

Question 31

Which intercostal space is the nipple found in nulliporous women?

Answer 31

4th intercostal space.

Question 32

What structure does the areola have?

Answer 32

It has sebaceous glands that secrete sebum for lubrication.

Question 33

What arteries supply the breast?

Answer 33

Medially - internal thoracic artery (internal mammary).Laterally - posterior intercostal artery.Superiorly - subclavian artery.

Question 34

Describe the lymph drainage of the breast.

Answer 34

Has a subareolar plexus around the areola. This drains into the right lymphatic duct (right side) and left thoracic duct (left side). 75% runs through the axillary nodes at the axilla.

Question 35

What is the relation between the lymph drainage of the breast to breast cancer?

Answer 35

If a tumour metastasizes, it can enter through the lymph system and spread elsewhere.