USMLE Forums banner
1 - 3 of 3 Posts

·
Ex-USMLE Forums Staff
Joined
·
753 Posts
Discussion Starter · #1 ·
There's no better than this original Gray's Anatomy illustration to study the diaphragm anatomy and embryology for the USMLE Step 1 exam.

Click on the thumbnail to enlarge it
Font Slope Diagram Auto part Line art
Image from Wikimedia public domain

T8 Level: Caval hiatus (Label 2) transmitting the inferior vena cava.

T9 Level: Foramen of Morgagni (Label 1) also called sternocostal hiatus two on each side of the xiphoid process. Transmitting the superior epigastric vessels.

T10 Level: Esophageal hiatus (Label 6) transmitting the esophagus and the vagus branches. Note how it's formed by the right cruse of the diaphragm.

T12 Level: Aortic haitus (Label 7) transmitting the aorta, the azygous vein, and the thoracic duct.

Label 3: this is an opening for the splanchnic nerves, there are several unnamed openings that are not asked in USMLE such as this one and others for the hemizygous vein and phrenic nerves.

Labels 4, 5: Note how the right crus is originating from L1-L2-L3 while the left crus is originating from L1-L2. To remember this, just remember that the right lung has three lobes and the left lung has two lobes :D

Medial Arcuate Ligament (Label 7) covering the psoas major and the Lateral Arcuate Ligament (Label 8) covering the quadratous lumorum.

Embryology:
The central tendinous portions are derived from the pleuroperitoneal folds and the septum transversum (both names looking like tendinous). While the crura are derived from the dorsal esophageal mesentry (that's why the right crus is wrapping (just like mesentry) the esophagus. The peripheral muscular portions of the diaphragm are derived from the body wall as it's obvious in the illustration above.
 

·
Registered
Joined
·
2 Posts
I remember like this!!
VENA CAVA = 8 letters =T8
OESOPHAGUS = VAGUS NERVE = 10 Letters= T10
ARCH OF AORTA(of course it not AOA which is passing, but just to remember)= THORACIC DUCT=12 letters = T 12
 
1 - 3 of 3 Posts
Top