The diaphragm is a thin fibro muscular partition that separates the abdomen and thorax. It is the primary muscle of respiration and has a central tendon and domes on the right and left sides. It attaches to the sternum, lower ribs, and vertebrae. There are openings for structures like the vena cava, esophagus, and aorta. During breathing, the diaphragm contracts to increase the vertical diameter of the thoracic cavity. It functions to inspire air into the lungs and acts as a thoracoabdominal pump to circulate blood. Clinical applications include diaphragmatic hernias and paralysis.

1. DIAPHRAGM
• Thin fibro muscular partition between abdomen and
thorax
• Important muscle of respiration

2. • Extent
Normal Breathing Full Expiration
Right At level of 4th Rib
nipple
Left One rib lower 5th rib

3. FEATURES
• Has fibrous central tendon
• Depressed in centre
• Raised on right and left side as domes or
cupola

4. ATTACHMENT
Origin :
• Sternal part – Inner surface
of xiphoid
• Costal part – Lower 6 costal
cartilages
• Vertebral – By
crura
-right
-left
Arcuate ligame
- Medial
- Lateral
- Median
Insertion:
• Central Tendon

5. OPENINGS IN DIAPHRAGM
•Venacaval – 8th thoracic vertebra
– inf venacava ,
-right phrenic nerve
•Oesophageal – 10th thoracic vertebra
– oesophagus,
-right & left vagal trunks,
-oesophageal branches of lt gastric vs
-lymphatics
•Aortic (Aortic hiatus) – 12th thoracic vertebra
–abdominal aorta,
-thoracic duct,
-azygos vein

6. OTHER OPENINGS
Superior epigastric vessels – sternal and costal origin
Subcostal nerve & vessel – posterior to lateral arcuate lig
Sympathetic trunk - posterior to medial arcuate lig
Splanchnic nerves - pierce crura
Left phrenic n - pierce left dome

7. SUPERIOR
RELATIONS
• Lung & pleura on dome
• Pericardium on central tendon
INFERIOR-lined by peritonium
• Right – right lobe of liver,
right kidney,
right suprarenal
• Left- fundus of stomach,
spleen
left kidney,
left suprarenal

8. Nerve supply

9. Blood supply
• Pericardiophrenic
• Musculophrenic
• Inf phrenic

10. ACTION
• Increases vertical diameter of thoracic cavity
FUNCTIONS
• Muscle of inspiration
• Muscle of abdominal straining
• Thoracoabdominal pump – forcing blood from
IVC to rt. Atrium
• Weight- lifting muscle

11. CLINICAL APPLICATIONS
1. Diaphragmatic
hernias
• aquired

12. • Congenital
• Due to defect in development
• Bochdalek’s hernia – lumbocostal gap
• Reterosternal hernia-through foamen of Morgagni

13. 2. Paralysis of diaphragm
3. Hiccups

14. MECHANISM OF RESPIRATION
Increase in
• vertical diameter by diaphragmatic contraction
• Anteroposterior diameter by pump handle movement of sternum
• Transverse diameter by bucket handle movements of lower ribs