Download THORACIC CAVITY

THORACIC CAVITY
RESPIRATORY
DIAPHRAGM
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.
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
Central Tendon
“Y-shaped”
 Attaches to lumbar vertebrae via crura.
 Pierced by three openings (described
later).

Central Tendon

Three parts to central tendon:
Right:
Largest part.
Middle:
Left:
Smallest part.

Fig. 2.71
Crura
Muscular pillars
 Originate from lumbar vertebrae:

Right from L3.
Left from L2.
Right swings left and forms a weak sphincter
around the esophagus.
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.
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
Diaphragm Innervation
Phrenic Nerve
 C3-5

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.