Lecture 4 - Diaphragm; Mechanisms of breathing

Question 1

Which Dome of the diaphragm is higher and why?

Answer 1

Right dome is higher

heart pushes the left dome lower

Question 2

The diapgram is a thin sheet of muscle that lines the entire thoracic cavity - has a central tendon

What does contraction lead to?

Answer 2

tendon moving downwards

Question 3

What are the attachements of the diaphragm:

Answer 3

Anteriorly: xiphoid process

Posteriorly: bumps into psoas major and qadratus lumborium (doesn’t reach posterior wall)

Costal Margin:Inferior six ribs and costal cartilages

Lumbar vertebrae: L1-3/4 via Right crus and L1-2/3 via left crus)

note: crus = legs

Question 4

Where is the median arcuate ligaemnt/

Answer 4

Right in the mid-line forms over the top of the descending aorta

Question 5

The medial arcuate lig. is ov ver which muscle?

Answer 5

Psoas major

Question 6

The lateral arcuate lig. is over which muscle?

Answer 6

Quadratus lumborum

Question 7

What are the structures that pierce the diaphragm and where do they do so?

Answer 7

IVC - T8 (slightly to the right)

Oesophagus - T10 (midline posterior)

Aorta - T12

Right phrenic n.: through central tendon

Left phrenic: anterolateral (through muscle)

Azygous Vein: Right

Hemiazygous vein: Left

Sympathetic trunk: Lateral to the cura

Question 8

The aorta passes behind the _____ _______ _______at T12

Answer 8

mnedian arcuate ligament

Question 9

As diaphragm pushses downwards it _____pressure in the abdominal cavity

Answer 9

increases

blood then wants to move to the lower pressure area = thoracic cavity

Question 10

When the D contracts it pulls ____ __ ___ ____ and closes off the ______, stopping the contents of the _____ going up like the blood does

Answer 10

When the D contracts it pulls the left and right crus and closes off the oesophagus, stopping the contents of the stomach going up like the blood does

Question 11

what innervates motor, sensory to central part and sensory to pericardium of diaphragm?

Answer 11

Phrenic nerve.

C 3,4,5 - keeps the diaphragm alive

Question 12

Where is pain from central diaphragm referred?

Answer 12

Dermatomes over the neck and upper limb (C3,4,5)

Question 13

The very lateral part of the diaphragm receives sensory supply from …

Answer 13

the lower intercostal nerve

Pain here will be referred to the lower thoracic spinal segments

Question 14

movement of air in and out of lungs is..

Answer 14

passive

created by pressure gradient by change in dimensions

Question 15

The lungs have to move in whatever direction the thoracic wall moves because of…

Answer 15

the surface tension produced by the pleura

Question 16

True or False

The parietal pleura is firmed attached to the thoracic cage, including the diaphragm

Answer 16

True

Question 17

The diaphragm expands the lungs by…

Answer 17

pulling down on them

Question 18

The diaphragm is the main determinant of _____ respiration

Answer 18

Silent respiration

Question 19

If you elevate the upper ribs, (external intercostals) - you increase the _______ direction of the cage

Answer 19

anteroposterior

Question 20

Elevation of lower ribs cause a increase in the _______ dimension

Answer 20

Elevation of lower ribs cause a increase in the transverse dimension

Question 21

What are the accessory respiratory muscles?

Answer 21

Scalene muscles - for sniffing

external intercostals - expanding

Internal intercostals - collapsing

Question 22

The _______ muscles tense in forced expiration to force abdominal contents up to push the diaphragm up and reduce thoracic cavity

Answer 22

The adbominal muscles tense in forced expiration to force abdominal contents up to push the diaphragm up and reduce thoracic cavity

Question 23

serratus anterior does what?

Answer 23

protracts scapula