respiration muscles Flashcards
classification of respiratory muscles
primary inspiratory
secondary inspiratory
primary expiratory muscles
secondary expiratory muscles
primary inspiratory muscles
diaphragm
external intercostals
levator costae
secondary inspiratory muscles are used when
there is forced breathing
secondary inspiratory muscles
scalenes
sternocleidomastoid
upper traps
serratus anterior
pec major and minor
abdominals
primary expiratory muscles
internal intercostals
sternocostalis
expiration is primarily a…
passive event d/t elastic recoil of the ribcage
secondary expiratory muscles
abdominals
–> rectus abdominus, obliques, transversus abdominus
when are primary muscles active
during quiet breathing
when are secondary muscles active
during forced breathing
exercises or pathology
inspiration
increase in A/P diameter of the chest
decrease pressure
air flows into the lungs
expiration
decrease volume and increased pressure
air moves out of the lungs
diaphragm origin
posterior surface of xiphoid process
inner surface of ribs 7-12 + costal cartilage
lumbar bodies and arcuate ligaments
diaphragm insertion
central tendon
what does the central tendon also have attachments to
pericardium
what shape is the diaphragm
dome shaped
contraction of the diaphragm
the central tendon pulls down and the diaphragm descends
descent of the diaphragm is stopped by stretch of the mediastinum
descent will compress the abdominal contents and increase intra-abdominal pressure
what happens once the descent of the central tendon has stopped (diaphragm contraction)
the muscle fibers continue to shorten
results in an upward pull on the lower ribs –> bucket handle motion
how do the external intercostals run
down and anteriorly
role of the external intercostals
elevate the ribs and assist with inspiration
how do the fibers of levator costae run
from transverse process down laterally to ribs
role of levator costae
assists in elevation of the ribs
internal intercostals fibers run
down and posteriorly
role of internal intercostals
assist with expiration
sternocostalis fibers run
down and medially from costal cartilage to sternum
role of sternocostalis
depress costal cartilage and assist with expiration
expiration is primarily
passive recoil of the rib cage
major function of abdominals
assist with forced expiration
role of abdominals during inspiration
helping increase intra-abdominal pressure
—-> pushing the lower ribs outward
when does activity of the abdominals increase
exercise
abdominals during expiration
as the diaphragm relaxes –> the abdominals contract —> pushes abdominal contents up
this raises the central tendon –> aides in expiration
what do the abdominals do as the diaphragm contracts
resist motion and act as a girdle
what would happen if the abdominals didn’t work as the diaphragm contracts
abdominal contents would be displaced inferiorly and anteriorly and the central tendon wouldn’t be stabilized
–> diaphragm wouldn’t elevate the lower ribs
what effect do the abdominals have on the diaphragm
improve the efficiency of the diaphragm
what happens if the abdominals are paralyzed
ventilatory efficiency of the diaphragm decreases
normal sequence of chest wall motions during quiet breathing
first
second
third
fourth
normal sequence of chest wall motions during quiet breathing –> first
diaphragm contracts and central tendon moves down
increases intra-abdominal pressure –> observe distension of abdomen
“belly breathing”
normal sequence of chest wall motions during quiet breathing –> 2nd
diaphragm continues to contract –> pushes lower ribs outward
observe lateral movement of lower chest
normal sequence of chest wall motions during quiet breathing –> 3rd
upper ribs rotate and elevate manubriosternum
observe anterior motion of the upper chest
2nd and 3rd steps may occur spontaneously
normal sequence of chest wall motions during quiet breathing –> 4th
expiration during quiet breathing is passive
observe recoil of chest wall
