THORACIC CAVITY

1
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
• 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
• Right
• 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
• 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
• 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.