Thoracic cage and mechanics of breathing Flashcards
what level is the suprasternal notch?
T2/3
what level is the sternal angle of Louis?
T4/5
what level is the inferior angle of scapula?
T8
what level is xiphisternum
T9
what level is the lowest part of costal margin, 10th rib?
L3
what are false ribs?
free ribs - 11 and 12
what are true ribs?
7,8,9
which ribs are most likely to fracture?
7-10
which ribs are least likely to fracture?
1 and 2 and 11 and 12
where is the weakest part of the rib?
middle/ side
fracture caused by coughing
pathological fracture
rib fractures in children
rare because bones are elastic and flexible
what do the lower ribs protect?
liver, spleen, diaphragm, abdominal viscera
thoracic outlet syndrome
C8 and T1 become compressed in the thoracic outlet, affecting the ulnar nerve . Unable to do fine movements of hand and flexion at wrist . Causes tingling in hands, white/ pale arms if subclavian artery compressed or blue arm if subclavian vein compressed
where is the apex of the lung?
comes out above clavicle
what could obstruct the superior thoracic aperture?
extra ribs (cervical) above 1st rib abnormal tight band connecting the spine to the ribs
anatomy of thoracic vertebrae
12 thoracic vertebrae
medium sized
main function - to articulate with the ribs
each thoracic vertebra has 2 demi facets
costal facet is on the transverse process except T11 and 12 which articulate with the tubercle of the rib
Pressures at rest
atmospheric = 760mmHg
Alveolar pressure = 760mmHg
Intrapleural pressure = 756mmHg
pressures during inhalation
atmospheric = 760mmHg Alveolar = 758mmHg Intrapleural = 754mmHg
level of diaphragm
T9 posteriorly
anteriorly level of 5th rib
higher on left due to the liver
diaphragmatic movement
increases vertical diameter of thoracic cavity .
contraction during inspiration causes it to flatten and moves downward leading to increase in the vertical diameter of thoracic cavity .
what are the most active muscle group in breathing?
diaphragm/ skirt
Inspiratory muscles during quiet breathing
diaphragm
external intercostals stabilise rib cage and move ribs up and out to increase diameter of thorax .
Inspiratory muscles during increasing effort
diaphragm
external intercostals move the ribcage up and out
neck muscles pull ribcage upwards
sternocleidomastoid elevate sternum and scalenus major and minor muscles elevate first 2 ribs and sternum
shoulder muscles will pull rib cage outwards > pecs and lat dorsi
what are the muscles of inspiration?
diaphragm external intercostals accessory muscles= sternocleidomastoid, anterior, middle and posterior scalenes pectoralis major and minor serratus anterior
expiratory muscles in quiet breathing
elastic recoil of tissues - chest wall and lungs. Normal exhalation is a passive process
expiratory muscles in increasing effort
becomes an active process and involves internal intercostals and abdominal wall muscles
what muscles are involved in expiration
internal and innermost intercostals
accessory muscles = rectus abdominis and transversus abdominis, external and internal oblique
what do the internal and innermost intercostals do in expiration
internal = depress interosseus parts of ribs during forced expiration
elevate interchondral parts of ribs during forced expiration
what do the accessory muscles of expiration do in expiration?
fix costal margin and increase intra-abdominal pressure
mechanics of movement
pump handle movement - increases the antero-posterior diameter of thoracic cavity. Upward movement of the upper ribs move the sternum upward and outward and increases the antero-posterior diameter of thoracic cavity .
bucket handle movement = increases the transverse diameter of the thoracic cavity . Upward and outward movements of the middle and lower ribs increase the transverse or lateral diameter of thoracic cavity .
what are the most active muscle groups in the pump handle movement?
intercostals
what are the most active muscle groups in the bucket handle movement?
intercostals
what innervates the diaphragm?
phrenic nerves
what innervates the intercostal muscles?
segmental thoracic nerves
what is the nerve root of the phrenic nerve?
C3,4,5
upper and lower surfaces of ribs
upper = blunt lower = sharp
fractured rib from coughing
pathological rib fracture
cervical pleura
above first rib
structure of pleura
cervical pleura above first rib
space for root of lung
pleura named based on what it is touching
what goes through the diaphragm?
inferior vena cava
oesophagus
aorta
Azygos system
veins that drain the thoracic wall and upper lumbar region via the lumbar veins and posterior intercostal veins
what type of muscle is the diaphragm?
fast twitch
not exercising with a respiratory condition
may use all the breathing muscles despite not exercising .
thoracic interventions
go above rib for pleural fluid
insert chest drain above rib to avoid the artery and vein
at anaesthetise the rib insert needle below the rib to hit the nerve
phrenic nerve palsy
causes hemidiaphragm, one side raises up
Injury to C5
patient will still be able to breathe but not move anything else
Injury to C2
no movement
patient will have to be on ventilator