Muscles of Respiration | Breathing Mechanics | Respiratory Physiology
Summary
TLDRThis video from Bite Size Med explores the muscles involved in respiration and the mechanics of the chest wall during breathing. It explains how inspiration and expiration are facilitated by the diaphragm, ribs, and accessory muscles. The diaphragm is the primary muscle for inspiration, flattening to increase thoracic volume, while expiration is generally passive due to lung elasticity. The video also highlights the role of external intercostal muscles and the importance of the phrenic nerve in diaphragm function. It concludes with a mnemonic to help remember the respiratory muscles and their actions.
Takeaways
- 🌀 The breathing cycle consists of inspiration (inhaling air into the lungs) and expiration (exhaling air out of the lungs).
- 🏗️ Changes in the volume of the thoracic cavity during respiration are achieved by altering its dimensions vertically, anteroposteriorly, and transversely.
- 📐 The ribs are hinged at the back and angle downwards to attach to the sternum, allowing for changes in the thoracic cavity's diameters.
- 💪 The diaphragm is the primary muscle of respiration, contracting to flatten and increase the vertical dimension of the thoracic cavity during inspiration.
- 🔄 During quiet breathing, expiration is a passive process due to the lungs' elastic properties and does not require muscle contraction.
- 📉 The external intercostal muscles are involved in inspiration, elevating the ribs and moving the sternum forward to increase the thoracic cavity's volume.
- 🔄 Accessory muscles, such as the sternocleidomastoid, serratus anterior, and scalene muscles, assist in respiration when extra effort is needed.
- 📚 The diaphragm is innervated by the phrenic nerve, which originates from C3, C4, and C5, and damage to this nerve can lead to diaphragmatic palsy.
- 📉 The internal intercostal muscles and abdominal wall muscles are involved in expiration, pulling the ribs down and reducing the thoracic cavity's volume.
- 🔄 Quiet expiration is generally a passive process due to the lungs' elastic recoil, but active muscle involvement indicates the need for extra effort.
- 👍 Remembering the muscles of respiration can be aided by associating inspiration with 'E' for external intercostals and expiration with 'I' for internal intercostals.
Q & A
What is the primary function of the diaphragm in the respiratory process?
-The diaphragm is the primary muscle of respiration responsible for most of the work during inspiration. When it contracts, it flattens, increasing the vertical dimension of the thoracic cavity, allowing the lungs to expand and draw in air.
What are the two phases of the breathing cycle?
-The two phases of the breathing cycle are inspiration, which is the process of taking air into the lungs, and expiration, which is the process of breathing air out.
How do the ribs contribute to the changes in the thoracic cavity's dimensions during respiration?
-The ribs, which are hinged at the back and angle downwards, can move to change the diameters of the thoracic cavity from front to back and sideways. The upper ribs move with a pump handle movement, increasing the anteroposterior diameter, while the lower ribs move with a bucket handle movement, increasing the transverse diameter.
What is the difference between active and passive expiration?
-Active expiration requires the use of muscles to force air out of the lungs, often during conditions like respiratory distress. Passive expiration, on the other hand, is the result of the lungs' elastic properties causing them to recoil, and it does not require muscle action during quiet breathing.
Which muscles are considered accessory muscles of respiration and when do they come into play?
-Accessory muscles of respiration, such as the sternocleidomastoid, serratus anterior, and scalene muscles, come into play during situations that require extra effort, like in respiratory distress, when the primary muscles are not sufficient.
How do the external intercostal muscles assist in inspiration?
-The external intercostal muscles are attached to the ribs and are directed forwards and downwards. When they contract, they elevate the ribs, contributing to the increase in the thoracic cavity's volume during inspiration.
What is the role of the internal intercostal muscles during expiration?
-The internal intercostal muscles are attached to the ribs with fibers that run downwards and backwards. They contract during expiration to depress the ribs, reducing the thoracic volume and aiding in the passive expulsion of air from the lungs.
What muscles are involved in the abdominal wall that assist in forced expiration?
-The muscles of the abdominal wall that assist in forced expiration include the rectus abdominis, external and internal obliques, and the transversus abdominis. These muscles pull the ribs down and increase intra-abdominal pressure, which helps force air out of the lungs.
What nerve supplies the diaphragm and what condition can occur if it is damaged?
-The diaphragm is supplied by the phrenic nerve, which originates from the cervical spinal nerves C3, C4, and C5. Damage to this nerve can result in diaphragmatic palsy, a condition that makes breathing difficult.
How does the movement of the ribs and sternum during inspiration and expiration relate to the anteroposterior and transverse diameters of the thoracic cavity?
-During inspiration, the ribs move up and the sternum moves forward, increasing the anteroposterior diameter. The lower ribs' bucket handle movement increases the transverse diameter. During expiration, the ribs move down and the sternum falls back, reducing both the anteroposterior and transverse diameters.
What is the mnemonic provided in the script to help remember the muscles involved in inspiration and expiration?
-The mnemonic provided in the script is 'E for I and I for E' to help remember that the external intercostal muscles are involved in inspiration and the internal intercostal muscles are involved in expiration.
Outlines
😀 Muscles of Respiration and Chest Wall Movement
This paragraph introduces the topic of respiratory muscles and the mechanics of the chest wall during breathing. It explains the breathing cycle, which includes inspiration (inhaling air into the lungs) and expiration (exhaling air out). The paragraph details how changes in the volume of the thoracic cavity are achieved through the movement of the ribs, sternum, and diaphragm. The diaphragm, a primary muscle of respiration, contracts during inspiration to increase the vertical dimension of the thoracic cavity, allowing the lungs to expand. During expiration, the diaphragm relaxes, and the lungs recoil due to their elastic properties. The paragraph also describes the role of the external intercostal muscles in elevating the ribs and sternum during inspiration and the involvement of accessory muscles during increased respiratory effort.
😉 Nerve Supply and Mechanics of Respiration
The second paragraph delves into the nerve supply of the diaphragm, highlighting the importance of the phrenic nerve which originates from cervical vertebrae C3, C4, and C5. Damage to this nerve can result in diaphragmatic palsy, affecting the ability to breathe. The paragraph summarizes the active process of inspiration, where the diaphragm and external intercostal muscles are primarily involved, along with accessory muscles such as the sternocleidomastoid, scalene muscles, and serratus anterior when extra effort is needed. It contrasts this with the passive process of quiet expiration, driven by the elastic recoil of the lungs and relaxed inspiratory muscles. If additional effort is required during expiration, muscles of the abdominal wall and internal intercostal muscles are engaged to depress the ribs and sternum. The paragraph concludes with a mnemonic 'e for i and i for e' to help remember the active and passive phases of respiration.
Mindmap
Keywords
💡Respiration
💡Chest Wall
💡Inspiration
💡Expiration
💡Diaphragm
💡Ribcage
💡External Intercostal Muscles
💡Accessory Muscles
💡Internal Intercostal Muscles
💡Abdominal Muscles
💡Phrenic Nerve
Highlights
The video discusses the muscles of respiration and chest wall movement during the breathing cycle.
Respiration involves inspiration (air intake) and expiration (air outtake), changing thoracic cavity volume.
Chest wall dimensions change vertically, anteroposteriorly, and transversely during respiration.
Rib movement is facilitated by their hinge at the back and angle to the sternum.
The diaphragm is the primary muscle of respiration, responsible for vertical movement.
Inspiration is an active process requiring muscle contraction, unlike passive expiration.
The diaphragm flattens during contraction, increasing the vertical dimension and allowing lung expansion.
Expiration involves the diaphragm relaxing, reducing thoracic volume, and lung contraction.
Ribcage and sternum movement is integral to changing anteroposterior and transverse diameters.
Upper ribs perform a pump-handle movement, increasing anteroposterior diameter.
Lower ribs execute a bucket-handle movement, increasing the transverse diameter.
Muscles of inspiration include the external intercostal muscles, which elevate the ribs.
Accessory muscles assist during increased respiratory effort, such as the sternocleidomastoid.
Accessory muscles include the serratus anterior and scalene muscles, among others.
Quiet expiration is typically passive, relying on lung elasticity and muscle relaxation.
Internal intercostal muscles and abdominal muscles are involved in active expiration.
The phrenic nerve is crucial for diaphragm function, with damage potentially leading to palsy.
A mnemonic 'e for i and i for e' is provided to remember the active and passive phases of respiration.
Transcripts
hi everyone welcome to bite size med
where we talk about quick bite-sized
concepts in basic medical sciences for
study and rapid review
this video is on the muscles of
respiration and how the chest wall moves
during respiration
the breathing cycle involves taking air
into the lungs that's inspiration
and breathing it out expiration this
involves changes in the volume of the
thoracic cavity
and that happens by changing its
dimensions vertically
anteroposteriorly and to some extent
transversely
how does this happen the ribs and the
sternum move
the ribs are hinged at the back and they
angle downwards to attach to the sternum
so they can move to change the diameters
from front to back and sideways
but what about vertically that's the
diaphragm
that is the muscle of respiration it
sort of takes on the entire load itself
inspiration is active muscles actually
actively have to contract for it to
happen
expiration is passive the lungs have
elastic properties
so it results in recoil when it
stretches
so in quiet expiration the muscles used
during inspiration
just relax so let's start with the
diaphragm
most of the work of inspiration is done
by the diaphragm alone
when it contracts it flattens so the
vertical dimension will increase
the lungs expand and air enters the
lungs
during expiration the opposite happens
the diaphragm relaxes
the thoracic volume reduces the lungs
contract
and air gets out the ribcage can move up
or down and since they're attached to
the sternum
when the ribs move up the sternum moves
forward
that increases the diameter from front
to back
when the ribs come down the sternum will
fall back
and the diameter reduces so ribs move up
and sternum moves forward in inspiration
the ribs come down the sternum falls
back in expiration
the upper ribs move with the pump handle
movement
so it moves the sternum up and down and
increases the anteroposterior diameter
the lower ribs have a bucket handle
movement
that increases the transverse diameter
but what moves the ribs muscles
so the muscles that elevate the ribs
will be those of inspiration
and those that depress the ribs will be
those of expiration
so in addition to the diaphragm the
external intercostal muscles are muscles
of inspiration
they are attached to the ribs and
directed forwards
and downwards to attach to the rib below
so sort of like the direction of your
hands when you put them in your jacket
pockets
so because of the direction of these
fibers when they contract
the ribs move up now these two muscles
are good enough during regular
inspiration
but when a little extra effort is needed
more muscles might be required
like in respiratory distress these are
called
accessory muscles they are accessory
and start working when needed
most of the muscles that attach to the
ribs can serve as accessory muscles
solve the muscles of the chest wall
some that are easy to remember start
with the letter s
like the sternocleidomastoid which like
the name suggests
originates from the sternum and the
clavicle so it can lift the sternum
which is helpful during inspiration
the others are the serratus anterior and
the scalene muscles
so like i said any muscle of the chest
wall can contribute
like the pectoral muscles the
transversus thoracic muscles
etc now that was all inspiration
and like i said it's active so there's a
lot of muscles
quiet expiration remember is passive so
quiet exploration doesn't need the
muscles to move
if muscles are being used it's because
extra
effort is needed and these are again
accessory muscles
so these muscles have to depress the
ribs to reduce the volume
now the external intercostals handle
inspiration
here the internal intercostals play a
role
they are also attached to the ribs but
their direction changes
they're downwards and backwards so it
makes sense that the action that they
have on the ribs is the opposite
they depress the ribs the ribs can also
be depressed by contraction of abdominal
muscles
the rectus abdominis the external and
internal
obliques the transversus abdominis they
pull the ribs down and also increase
intra-abdominal pressure
so they can also elevate the diaphragm
and if the lung gets smaller it forces
more air out
the nerve supply to these muscles is
important particularly the diaphragm
the diaphragm is supplied by the phrenic
nerve which originates from c3
c4 and c5 if there's damage to this
nerve
there can be diaphragmatic palsy which
makes it difficult to breathe
so let's put it all together inspiration
is active
most of the job is done by the diaphragm
also the external intercostals
they move the ribs up and the sternum
forwards
accessory muscles are the
sternocleidomastoid
the scalene muscles serratus anterior
and other muscles of the chest wall
expiration quietly is passive it's from
elastic recoil
the muscles of inspiration relax if
extra effort is needed muscles come into
play
the muscles of the abdominal wall and
the internal intercostals
they pull the ribs down and the sternum
falls backwards
so e for i and i for e if you get
confused
and those are the muscles of respiration
and how the chest moves during
respiration
if this video helped you give it a
thumbs up share and subscribe thanks for
watching and i'll see you in the next
one
Посмотреть больше похожих видео
5.0 / 5 (0 votes)