Diaphragm

Question 1

What is the diaphragm?

Answer 1

Dome-shaped musculotendinous partition that separates thoracic and abdominal cavities; its the chief muscle of inspiration and forms the convex floor of thoracic cavity and concave roof of abdominal cavity

Question 2

How does the diaphragm behave during respiration?

Answer 2

Descends during inspiration → only central part moves, since its periphery is attached to the inferior margin of thoracic cage and superior lumbar vertebrae
Ascends during expiration, same as in inspiration, only that this time the diaphragm curves superiorly and forms two domes

Question 3

Which domes does the diaphragm curve superiorly and what is the main difference between one another?

Answer 3

Right and left; normally, the right dome is higher than the left (liver)

Question 4

Where is the muscular part of the diaphragm situated and where do the fibers of this converge?

Answer 4

Muscular part is situated peripherally with fibers that converge radially on the trifoliate central aponeurotic part, the “central tendon”

Question 5

Where is the central tendon located?

Answer 5

Althoughit lies near the center of the diaphragm, its closer to the anterior part of the thorax

Question 6

How is the muscular part of the diaphragm divided?

Answer 6

Sternal, costal, and lumbar part

Question 7

What does the sternal part of the diaphragm consist of?

Answer 7

2 muscular slips that attach to the posterior aspect of the xiphoid process of sternum

Question 8

What does the costal part of the diaphragm consist of?

Answer 8

Wide muscular slips that attach to the internal surfaces of the inferior 6 costal cartilages and their adjoining ribs on each side; this part forms the domes of the diaphragm

Question 9

What does the lumbar part of the diaphragm consist of?

Answer 9

Arises from 2 aponeurotic arches (medial and lateral arcuate ligaments) and the three superior vertebrae; this part forms right and left muscular crura that ascend to the central tendon

Question 10

What are the crura of the diaphragm?

Answer 10

Musculotendinous bundles that arise from the anterior surfaces of the bodies of the superior 3 lumbar vertebrae, the anterior longitudinal ligament, and the IV discs

Question 11

From where does the right crus arises from?

Answer 11

Arises from the first 3 or 4 lumbar vertebrae; this is usually larger and longer than the left crus

Question 12

From where does the left crus arises from?

Answer 12

Arises only from the first 2 or 3 lumbar vertebrae

Question 13

The crura are united by the…

Answer 13

Median arcuate ligament, this passes over the anterior surface of the aorta

Question 14

To which structures does the diaphragm attach on each side?

Answer 14

Medial and lateral arcuate ligaments; these are thickenings of the fascia covering the psoas and quadratus lumborum muscles, respectively

Question 15

Name the main diaphragmatic apertures and the main structures that pass through these

Answer 15

Caval (IVC), esophageal (esophagus), and aortic (aorta, azygos vein, and thoracic duct)

Question 16

What are the diaphragmatic apertures?

Answer 16

Openings on the diaphragm that allow structures to pass between the thorax and the abdomen

Question 17

Where is the caval opening located?

Answer 17

• Aperture in the central tendon; located to the right of the median plane at the junction of the tendon’s right and middle leaves
• This is the most superior of the three diaphragmatic apertures
• Lies at the level of T8 vertebra

Question 18

Where is the esophageal hiatus located?

Answer 18

Oval aperture in the muscle of the right crus of diaphragm at the level of T10 vertebra

Question 19

What characterizes the fibers of the right crus?

Answer 19

These decussate inferior to esophageal hiatus, forming a muscular sphincter for the esophagus that constrict when diaphragm contracts (reason why we can’t swallow and breath at the same time)

Question 20

Where is the aortic hiatus located?

Answer 20

Opening posterior to the diaphragm

Question 21

Where is the sternocostal triangle?

Answer 21

Small opening between sternal and costal attachments of the diaphragm

Question 22

What role does the caval opening have in blood flow of the IVC?

Answer 22

Since the IVC is adherent to the margin of the opening, it dilates and constrict the vein as the diaphragm contracts and relaxes during respiration, facilitating blood flow to the heart

Question 23

Does the aortic hiatus affect the blood flow of the aorta?

Answer 23

NO. The aorta doesn’t pierce the diaphragm, it passes between the crura of the diaphragm posterior to the median arcuate ligament (at the level of T12 vertebra)