Mechanics of Ventilation

Question 1

Functions of thorax

Answer 1

Move with ventilation

Protect organs

Question 2

What happens to the thorax as you age?

Answer 2

It widens and looses compliance (stiffer)

Loose AP diameter, ribs become more horizontal

Question 3

Which ribs only articulate with 1 vertebral body?

Answer 3

1, 10, 11, 12

Question 4

Is the thorax open chain or closed chain?

Answer 4

Closed chain, excluding ribs 11 and 12 (open chain)

Question 5

What do ribs articulate with?

Answer 5

Bodies, transverse processes and disc;

1, 10, 11, 12 with facets of body only

Question 6

What is the axis of motion through in the Ribs?

Answer 6

Through the CV and the CT joints

Question 7

What plane is the axis of rotation for the upper ribs?

Answer 7

close to the frontal plane

Question 8

What plane is the movement for the upper ribs in?

Answer 8

sagittal plane

Question 9

What plane is the axis of rotation for the lower ribs?

Answer 9

close to the sagittal plane

Question 10

What plane is the movement for the lower ribs in?

Answer 10

frontal plane

Question 11

What can the upper and lower ribs be compared to?

Answer 11

Upper ribs = pump handle

lower ribs = bucket handle

Question 12

Ribs 1-10 articulate posteriorly with vertebral bodies by what joint(s)?

Answer 12

2 synovial joints: CV and CT

Question 13

Describe the osteokinematic motion of the ribs:

Answer 13

ribs moving on the vertebral spine

Question 14

Describe the expansion of the ribs:

Answer 14

doesn’t incorporate movement of the bones

Question 15

Central tendon of diaphragm is

Answer 15

non-contractile

Question 16

Displacement of the diaphragm causes _______ , which draws air in.

Answer 16

negative pressure

Question 17

The diaphragm shortens during ______.

Answer 17

inspiration

Question 18

At rest, diaphragm muscle fibers are oriented ______.

Answer 18

longitudinally

Question 19

What muscles are primary muscles of inspiration?

Answer 19

diaphragm
intercostals
scalenes

Question 20

When do scalenes have optimal length-tension?

Answer 20

late inspiration

remember, they attach to cervical vertebrae-ribs 1/2 and act to lift thorax up

Question 21

What are the accessory muscles of inspiration?

Answer 21

SCM, upper traps, serratus anterior, pec major/minor (reverse action), lats(reverse action)

Question 22

When does the SCM kick in?

Answer 22

assists during inspiration with pathology or exertion

Question 23

With a T3 SCI, what position makes breathing easier?

Answer 23

supine: abdominal contents have external support of table (could also use abdominal binder in seated)

Question 24

What adaptations occur with hyperinflated lungs during inspiration?

Answer 24

increased lateral excursion, trap elevation. adaptations due to decreased contractility of diaphragm and chest wall due to length-tension changes.

Question 25

What are the muscles of expiration?

Answer 25

abdominals (rectus, external, internal, transverse), triangularis sterni, QL

Question 26

Describe the general results of expiration:

Answer 26

passive, thorax returns to resting state, diaphragm returns to dome shape, abdominal contents return to starting position

Question 27

Describe the biomechanics of breathing:

Answer 27

diaphragm contracts, ↑ intra-abdominal pressure, ↑ thoracic volume vertically/transversely, ↓ intrathoracic pressure

Question 28

Upward & outward motion of lower ribs is called

Answer 28

→ bucket handle motion

Question 29

A/P motion of upper ribs is called

Answer 29

→ pump handle motion

Question 30

What are the 3 phases of a cough?

Answer 30

1. deep inhalation 2. isometric contraction 3. forced expiration

Question 31

What muscles are involved in cough?

Answer 31

rectus abdominus, transverse abdominus

Question 32

What are consequences of ↑ WOB?

Answer 32

↑ levels of 02 demand, ↑ recruitment of accessory muscles, ↑ 02 COST OF VENTILATION (these are result of pathology)

Question 33

Decreased compliance of thoracic cage due to R thoracic scoliosis leads to:

Answer 33

R side compressed: decreased ability to contract because of decreased length L side stretched: decreased ability to contract because of increased length