1. RESPIRATORY DIAPHRAGM
THORACIC CAVITY
RESPIRATORY DIAPHRAGM

2. Diaphragm
A diaphragm is a muscular sheet with an inferior and a superior fascia:
Superior fascia = parietal thoracic fascia.
Inferior fascia = transversalis fascia.
Separates thorax and abdomen.
In moderate expiration:
Reaches level of 5th rib on right side and 5th IC space on left.

3. Diaphragm Origins Sternal part: Costal part: Lumbar part:
Xiphoid process.
Costal part:
Lower 6 ribs and cartilages.
Lumbar part:
Lumbar vertebrae and crura:
Right: L1-L3
Left: L1-L2

4. Central Tendon “Y-shaped” Attaches to lumbar vertebrae via crura.
Pierced by three openings (described later).

5. Central Tendon Three parts to central tendon: Fig. 2.71 Right: Middle:
Largest part.
Middle:
Left:
Smallest part.
Fig. 2.71

6. Crura Muscular pillars Originate from lumbar vertebrae: Right from L3.
Left from L2.
Right swings left and forms a weak sphincter around the esophagus.

7. Arcuate Ligaments Median: Medial: Lateral: Around aortic opening.
Bridges proximal ends of crura.
Medial:
From deep fascia of psoas major muscle.
From transverse process to body of L1.
Lateral:
From deep fascia of quadratus lumborum muscle.
From transverse process of L1 to rib 12.

8. Diaphragm Openings Caval opening: Esophageal opening: Aortic opening:
Level T8
Inferior vena cava; right phrenic nerve
Esophageal opening:
Level T10
Esophagus; vagus nerves
Aortic opening:
Level T12
Aorta; thoracic duct; azygos vein

9. Diaphragm Innervation
Phrenic Nerve
C3-5

10. Diaphragm Arterial Supply
Superior aspect:
Pericardiacophrenic artery from IT.
Musculophrenic artery from IT.
Superior phrenic artery from aorta.
Inferior aspect:
Inferior phrenic artery from aorta.