57. Thoracic diaphagm – position, description, blood and nerve supply.

DIAPHRAGM

T8 - L3

• The diaphragm is the primary muscle for inspiration.

Structure:

Origin:

The diaphragm has 3 origins:

1. Sternal part

• ↳ From back of xiphoid process.

2. Costal part:

• ↳ From Internal surfaces of lower costal cartilages & ribs 7-10

3. Lumbar part:

1. A) right crus: anterolateral surface of first 3 lumbar vertebrae and IVDs. L1 - L3
2. B) left crus: anterolateral surface of first 2 lumbar vertebrae and IVD. L1 - L2
3. C) medial arcuate lig.: from body of vertebra to front of transverse process.
4. D) lateral arcuate lig.: from transverse process to 12th rib.

* There is also the median arcuate ligament. Connecting the medial margins of the 2 crura.

Insertion: Central tendon of diaphragm.

• Has 2 surfaces. thoracic & abdominal

Innervation:

Phrenic nerves (C3-C5)

Blood Supply:

• Subcostal art.
• Sup. & Inf. phrenic arts.

Major openings of diaphragm:

1. Vena Caval

• At the level of T8 to the right
• It gives passage for:
• IVC
• Branches of right phrenic nerve.

2. Esophageal hiatus:

• At the level of T10 to the left
• passage for:
• esophagus
• Ant. & post. vagal trunks

3. Aortic

• At the level of T12 in the midline.
• passage for:
• Aorta
• Thoracic duct.