Diaphragm

Question 1

What is a diaphragm?

Answer 1

It is a double-domed, musculotendinous partition, separating the thoracic cavity from the abdominal cavity.
The central portion is a tendon. CENTRAL TENDON is the muscular part of the diaphragm.
The CONCAVE surface forms the roof of the abdominal cavity and the CONVEX superior surface faces and forms the floor of the thoracic cavity.

Question 2

Why is the right dome higher than the left?

Answer 2

Because the liver is located immediately inferior to the right.

Question 3

What are the diaphragm attachments?

Answer 3

1. The STERNAL PART (STERNUM) is posterior to xiphoid process
2. COSTAL MARGINS (RIGHT & LEFT PART) is inferior 6 costal cartilages and ribs
3. LUMBAR PART - right and left crura insert into central tendon

Question 4

What are the cruras of diaphragm?

Answer 4

CRURA are musculotendinous bands.
RIGHT CRUS is larger and longer than the left. It appears as a triangular mass anterior to the aorta.
LEFT CRUS arises from the first 2 Lumbar Vertebrae

Question 5

What are the apertures (openings/hiatus) of the diaphragm?

Answer 5

Diaphragm Apertures permit structures like esophagus, blood vessels, nerves and lymphatic vessels to pass between the thorax and abdomen.
The three larger apertures are:
1. CAVAL HIATUS - is primarily for the IVC. It is the most superior of the three diaphragmatic apertures.
Diaphragmatic contraction during inspiration widens the opening which allows the IVC to dilate and helps facilitate blood flow through this large vein to the heart.
2. ESOPHAGEAL HIATUS - is an oval opening located in the muscle of the right crus at the T10 level.
3. AORTIC HIATUS - passes between the crura posterior the median arcuate ligament at the inferior border of the T12 vertebra.

Question 6

What are the Diaphragmatic Functions?

Answer 6

Primary Functions
ON INSPIRATION - diaphragm contracts; moves inferior
ON EXPIRATION - diaphragm relaxes; moves superior

Secondary Functions

1. Maintains relative pressure between thorax and abdominal cavity
2. Assists IVC blood flow to heart
3. Expulsion actions - coughing, sneezing, vomiting

Question 7

What is the Sonographic Apprearance of the diaphragm?

Answer 7

Thin, Hyperechoic curve

Question 8

What is the Sonographic Appearance of Crura?

Answer 8

1. Thin, hypoechoic linear structure
2. Runs between the Aorta and the IVC
3. Anterior to proximal abdominal aorta
4. Posterior to IVC
5. Superior to the Celiac Axis

Question 9

Give me the Summary of the Diaphragm

Answer 9

1. Primary muscle used in respiration
2. Divides thorax and abdominal cavity
3. Moves inferior with inspiration
4. Appears as a hyperechoic curved line on ultrasound