UNIT 3: Muscles of Respiration Flashcards
what is pressure?
force exerted on walls of a chamber by gas molecules
at rest what is the pressure inside the thoracic cavity the same as?
atmospheric pressure
pressure = ____/_____, therefore…
force over area, as area inc pressure dec, as area dec pressure inc
positive pressure in the thoracic chamber means it is ___ than atmospheric pressure
greater
negative pressure in the thoracic chamber means it is ___ than atmospheric pressure
less
according to boyle’s law, increasing the volume of the thorax/lungs and will ___and will lead to …
dec intrathoracic pressure, air being drawn into the lungs (to equalize pressure w atmosphere)
according to boyle’s law, decreasing the volume of the thorax/lungs and will ____ ___and will lead to …
inc intrathoracic pressure, air will move out of the lungs (to equalize w atmosphere)
what are the 3 planes of thoracic volume change?
vertical
transverse (bucket handle)
anterior-posterior (pump handle)
describe vertical thoracic volume change
- inc primarily due to contraction of the diaphragm
- elevation of manubrium and 1st rib may also inc vertical dimension
describe transverse thoracic volume change
- “bucket handle” - up and out
- inc w elevation of ribs afforded by accessory muscles
describe anterior-posterior thoracic volume change
- “pump handle”
- inc w elevation of ribs via accessory muscles
what are the 2 types of inspiration?
quiet (rest) and forced (inc oxygen needs)
quiet inspiration (active passive?, muscles?)
- requires muscle activation
- diaphragm is most important, does most of the work of quiet inspiration
forced inspiration (active passive?, muscles?)
- requires muscle activation
- accessory muscles
two types of expiration
quiet expiration, forced expiration
quiet expiration (active passive?, muscles?)
- involves passive forces only (no active forces)
- gravity pulls ribs back to rest
- elasticity: when lungs are stretched by inc thoracic volume they will return to original shape and size when released
forced expiration (active passive?, muscles?)
requires muscles activation + passive forces
how many attachment points do skeletal muscles often have?
2
muscle fibres pull ___ their origin, moving the ____ point closer to the _____
toward, insertion, origin
what are the 3 primary muscles of inspiration
- diaphragm
- external intercostals
- interchondral portion of internal intercostals
describe the diaphragm
- only unpaired muscle of respiration
- separates thoracic and abdominal cavities
- participates in quiet inspiration and forced inspiration
- contraction inc volume of thorax in vertical dimension
where does the diaphragm attach?
vertebrae via crura (right crus and left crus)
what is the central tendon of the diaphragm?
- leaf shaped aponeurosis
- striated muscle fibers that surround central tendon
- provides floor for mediastinal organ
- compresses abdominal structures cyclically during respiration
what are the 3 hiatuses of the diaphragm?
- aortic hiatus
- esophageal hiatus
- foramen vena cava
what is the aortic hiatus of the diaphragm for?
houses the descending abdominal aorta
what is the esophageal hiatus of the diaphragm for?
houses esophagus
what is the foramen vena cava of the diaphragm for?
inferior vena cava
diaphragm is shaped like
an inverted bowl
where does the diaphragm originate
- thoracic ribs inner surface
- xiphoid process
- upper lumbar vertebra via crura
where does the diaphragm have its insertion point
central tendon
The diaphragm increases the
vertical dimension of the thorax
The diaphragm is innervated by the
phrenic nerve
where does the phrenic nerve originate?
cervical plexus from C3, C4, C5 bilaterally
the phrenic nerve descends through the _____ into _______ space on left and right sides of the ______
neck
mediastinal space
heart
The phrenic nerve mediates ______ for the _____
both sensory and motor info for the diaphragm