Senario Three - The Thorax

Question 1

State the boundaries of the thorax

Answer 1

thoracic vertebrae
ribs
costal cartilige
sternum 
diaphragm

Question 2

state the contents of the thorax

Answer 2

lungs, pleura, heart, major vessels, mediastinum

Question 3

Describe the structure of the sternum

Answer 3

three parts - manubrium, body and xiphoid

lateral surface - facets for attachments of costal cartilage
manubriosternal joint - hinge joint that moves in respiration

Question 4

how many true ribs are there? what are they?

Answer 4

upper 7 pairs

attach to sternum via their own CC

Question 5

how many false ribs are there? what are they?

Answer 5

8th, 9th and 10th ribs

attach to a common CC then to sternum

Question 6

how many floating ribs are there? what are they?

Answer 6

11th and 12th ribs

Don’t attach to sternum

Question 7

Describe the anatomy of the rib

Answer 7

anterior end - cup shaped depression for CC

shaft twists along its axis - forms costal groove

posterior end - head - two demi facets to attach to BODY of vertebrae above and below

posterior end - neck - medial oval tubercle - attach to TP & lateral tubercle - ligament attachment

Question 8

where do the ribs attach to the thoracic vertebrae?

Answer 8

at the inferior and superior facets of the body via the head

to the TP via the medial tubercle of the rib – reciprically curved on vertebrae T2 - T8 - allows some movement at the joint

Question 9

what are the atypical vertebrae and why?

Answer 9

T9 - T12 - only one facet on body

T11 and 12 - no facet on TP

Question 10

what type of joint is the manubriosternal joint?

Answer 10

secondary cartilaginous joint

hinge allowing small amounts of movement

no capsule and no ligaments

Question 11

what type of joint is the sternocostal joint? at rib 1

Answer 11

cartilaginous joint between medial end of CC and sternum

Question 12

what type of joint is the sternocostal joint from ribs 2 - 7?

Answer 12

synovial joint

Question 13

what ligaments support the sternocostal joint?

Answer 13

anterior and posterior radiate ligaments

pass from medial end of CC - superiorly, horizontally and inferiorly to the sternum

superior fibres interlace with adjacent and opposite ligaments of the joint

Question 14

what is the classification of the costocondral joints?

Answer 14

joint between the cup shaped depression on anterior rib and the costal cartilage

synovial cartilaginous from ribs 1-8
fibrous cartilaginous from ribs 9 and 10

Question 15

what is the interchondral joint?

Answer 15

between the tips of the 8/9/10 ribs and the cartilage above

• fibrous capsule surround the joint
• anterior and posterior radiate ligaments between adjacent CCs

Question 16

what is the costovertebral joint?

Answer 16

synovial plane joint between the convex articular facet on head of rib and concave demifacets on upper and lower vertebrae

loose fibrous capsule thickened anteriorly by radiate ligament of head of rib

Question 17

what is the radiate ligament of head of rib?

Answer 17

runs superiorly to upper vertebral body
transversely to front of IV disc
inferiorly to vertebral body below

blends with posterior longitudinal ligament

Question 18

what is the costotransverse joint?

Answer 18

synovial plane joint - between the tubercles of ribs 1-10 and corresponding TPs

allow gliding movement (and rotation at upper 6 ribs)

Question 19

what strengthens the costotransverse ligament

Answer 19

thin and fibrous capsule

• lateral costotransverse ligamnet
• costotransverse ligament
• superior costotransverse ligament - anterior and posterior bands

Question 20

what is Boyles law?

Answer 20

change in volume = change in pressure

Question 21

What occurs during inhalation

Answer 21

before inhalation pressure in lungs = to pressure in atmosphere - so no air movement

Diaphragm contracts - increased vertical diameter of thorax
external intercostals contract - ribs move up and out -increased AP and transverse diameter of thorax

increased volume of thorax means decreased pressure of thorax

air moves down pressure gradient

75% due to increase vertical diameter
25% due to increase AP and transverse diameter

Question 22

what are the roles of the accessory movements in forced inhalation

Answer 22

SCM and scalene elevate sternum and first 2 ribs

pec minor elevates ribs 3/4/5

Question 23

What occurs during exhalation

Answer 23

pressure in lungs = pressure in atmosphere

diaphragm relaxes and shortens due to recoil
external intercostals relax - ribs move down and in

decrease in vertical, lateral and anteposterior diameters - decrease in lung volume

pressure in lungs increases air moves out

Question 24

what are the roles of accessory movements in forces exhalation?

Answer 24

abdominals contract - further decrease vertical diameter

internal intercostals - bring ribs down and in - decrease AP and transverse diameter of the ribs

Question 25

what are the movements at the ribs during inhalation?

Answer 25

1st rib - fixed 2nd to 5th ribs - move at costotransverse and costovertebral joints - anterior ends raised - lift the sternum forwards and up 8th to 10th ribs move at the costovertebral and sternocostal joints - ribs move up and out

Question 26

what is the bucket handle mechanism

Answer 26

side to side movement at costotransverse and sternocostal joint increases transverse diameter rib is raised and everted

Question 27

what is the pump handle mechanism

Answer 27

backwards rotation of rib at neck causes elevation of anterior rib - pushes sternum forwards - increased AP diameter movement between costotrasnverse and costovertebral joints

Question 28

what muscles are active in quiet respiration?

Answer 28

diaphragm primary contractor scalene fix first rib

Question 29

what muscles are active in deep respiration?

Answer 29

diaphragm intercostals assist rib movement scalene fix first rib quadrates lumborum fixes 12 rib

Question 30

what muscles are active in expiration

Answer 30

- none - passive recoil of diaphragm and lungs

Question 31

what muscles are active in forced expiration

Answer 31

abdominals and latissimus dorsi

Question 32

Define and state the volume of: tidal volume

Answer 32

the volume of one breath approx 500ml

Question 33

Define and state the volume of: inspiratory reserve volume

Answer 33

the volume when taking a deep breath 1900- 3100 ml

Question 34

Define and state the volume of: expiatory reserve volume

Answer 34

the amount of air exhaled forcibly following normal inhilation 1200-1700ml

Question 35

Define and state the volume of: FEV1

Answer 35

volume of air exhale forcibly in one second following maximal inhilation

Question 36

Define and state the volume of: Residual Volume

Answer 36

amount of air remaining in the lungs following exhilaiton 1100-1200ml

Question 37

Define inspiratory capacity

Answer 37

tidal volume + IRC

Question 38

Define functional residual capacity

Answer 38

RV + ERC

Question 39

Define vital capacity

Answer 39

IRV, ERV and tidal volume

Question 40

define total lung capcaity

Answer 40

VC and RV

Question 41

what is the FVC/FEV1 ratio

Answer 41

forced expiratory capacity vs forced expiratory volume in one second

Question 42

why would you look at FVC/FEV1?

Answer 42

FVC reduced in restrictive diseases - ie. lungs smaller | FEV1 reduced in obstructive diseases - i.e. air is harder to move out

Question 43

attachments of the diaphragm

Answer 43

posterior xiphoid, internal CC of lower 6 ribs, R and L crura of lumbar vertebrae and accurate ligaments, pericardium of the heart inserts onto the central fibrous tendon

Question 44

openings of the diaphragm

Answer 44

T8 - vena cava T10 - oesophagus T12 - aorta

Question 45

nerve supply to diaphragm

Answer 45

phrenic nerve - C3, 4, 5

Question 46

how does the diaphragm descend

Answer 46

via the central tendon - 1.5cm in quiet breathing - limited by stomach and liver 5-10cm in deep breathing

Question 47

what are the DoF for external intercostals

Answer 47

down and medially - hands in pockets

Question 48

what are the DoF for internal intercostals

Answer 48

up and back

Question 49

what is the action of internal intercostals

Answer 49

depress ribs - keeps IC spaces rigid

Question 50

what is the action of external intercostals

Answer 50

elevate ribs - keeps IC spaces rigid

Question 51

what is the action of the innermost intercostals

Answer 51

keep IC spaces rigid | contain the neuromuscular bundle

Question 52

what is the mediastinum

Answer 52

central part of the thorax- contains the heart, thymus, oesophagus, trachea

Question 53

what is the plura?

Answer 53

double layered serous membrane - parietal - attaches to thoracic wall - visceral - attaches to surface of the lung cavity between filled with plural fluid - decreases friction in breathing fluid keeps the membranes in contact