1. Respiration has two stages - inspiration and expiration. Inspiration is active and involves contracting muscles like the diaphragm and external intercostals, while expiration is usually passive upon relaxation of these muscles. 2. The diaphragm is the chief muscle of respiration. When it contracts, its dome shape is lowered, increasing the vertical chest diameter and decreasing intrathoracic pressure, drawing in air. 3. The external intercostals elevate the ribs during inspiration, increasing the chest's transverse and anteroposterior diameters. This produces both a "bucket-handle" and "pump-handle" motion of the ribs and sternum, respectively.

1. Mechanism of Respiration
1

3. Mechanism of Respiration

4. Contents of PPT
• 1) Mechanism of Respiration
• 2) 2 Stages of Respiration
• 3) Muscles of Respiration
• 4) Bucket Handle movement of ribs
• 5) Pump Handle movement of Sternum
• 6) Role of Expiratory Muscles
• 7) Role of Accessory Muscles

5. Mechanism of Respiration
• 2 Stages of Respiration –
• i) Inspiration = Intake of Atmosphere air
• ii) Expiration = Giving out of Alveolar air
• RR = 14 to 18 / min .This is brought about by
Muscles of Respiration

6. Muscles of Respiration
• Muscles of inspiration = a) Diaphragm b)
External Intercostal Muscles
• Muscles of Expiration = a) Internal Intercostal
Muscles b) Abdominal muscles
• Accessory muscles of Respiration =
• a) Levator Scapulae
• b) Sternomastoid
• c) Scaleni
• d) Muscles of Nostril ( Ala Nasi)

7. Muscles of Respiration
Intercostal Muscles Diaphragm

8. Accessory muscles of Respiration
Muscles of Nostril ( Ala Nasi) Muscles of Nostril ( Ala Nasi)

9. Accessory muscles of Respiration
Scaleni Sternocleidomastoid

10. Accessory muscles of Respiration-
Levator Scapulae

11. Inspiration & Expiration
• During quiet respiration ,Inspiration is active (
Due to contraction of muscles of Respiration)
• Expiration is Passive ( Due to Relaxation of
Muscles of Respiration )
• In quiet breathing – Expiratory muscles &
Accessory muscles have No role ( They work
only during Exercise –when Ventilation is to be
increased )

12. Diaphragm
• Chief Muscle of Respiration
• Membranous muscle ,which separates
abdomen & thorax
• Originates from Xiphisternum ,Costal
cartilages & Vertebrae .Supplied by
Phrenic Nerves

13. Diaphragm –Action
• Dome shaped muscle .When it contracts
,dome is lowered .Verticle diameter of chest
increases – Volume of chest increases – Intra
Thoracic Pressure falls – Inspiration takes
place ( Air moves from Higher Pressure to
Lower pressure )
• When Diaphragm relaxes ,Expiration occurs
passively

15.  Rib movement.
 1 Pump
handle
movement.(2-
6th)
 2 Bucket
handle
movement.(7-10th)
 Contraction of
external intercostal
muscles.

16. b) External Intercostal Muscles
• Present outer side of ribs ,directed downward
,forward & medially
• Supplied by Intercostal nerves
• When they contract – bring about 2 types of
movements as follows –
• i) Bucket Handle Movement of Ribs
• ii) Pump handle movement of Sternum

17. Bucket Handle movement of ribs
• Normally ribs are oblique .When External
intercostals muscles contract --- Oblique ribs are
elevated – they become horizontal – Transverse
diameter of chest increases – volume of chest
increases --- Intra Thoracic pressure falls –
Inspiration takes place
• When muscle relax – ribs again become oblique &
expiration occurs passively
• This movement is seen in lower ribs –Movement is
like handle of bucket

18. Bucket Handle movement of ribs

19. Pump Handle movement of Sternum
• When oblique ribs become horizontal ,they
push body of Sternum anterior --- AP
Diameter of chest increases – Intra Thoracic
pressure falls – Inspiration takes place
• When ribs become oblique again – Sternum
moves posterior & Expiration occurs
• This movement of body of Sternum on
Manubrium is called Pump Handle Movement

20. Pump Handle movement of Sternum

21. 2) Role of Expiratory Muscles –
• Internal Intercostal muscles ,when contract –
they make ribs Oblique & Forceful Expiration
occurs
• When abdominal muscles contract –Intra
abdominal pressure is raised – Diaphragm
moves up & forceful Expiration occurs

22. 3) Role of Accessory Muscles
• Most of these muscles are attached to Inlet of
chest
• When they contract – Upper ribs & clavicle is
elevated + Nostrils also open widely ---
Ventilation is enhanced
• Note – Expiratory & Accessory muscles work
only during Exercise

23. Suripto, Spd -- SMANSA