Diaphragm is a thoracoabdominal organ which is musculotendinous. It is the primary muscle of respiration.
Extension:
- Sternal – xiphoid process and transverse abdominis aponeurosis
- Costal – lower 6 ribs and costal cartilage
![diaphragm inferior view](https://epomedicine.com/wp-content/uploads/2024/01/1113_The_Diaphragm.jpg)
There are 2 crura of diaphragm:
- Right crus – L1 to L4
- Left crus – L1 to L3
3 ligaments:
- Lateral arcuate ligament
- Medial arcuate ligament
- Median arcuate ligament
Quadratus lumborum muscle is related to lateral arcuate whereas psoas muscle is related to medial arcuate ligament.
![Diaphragmatic openings](https://epomedicine.com/wp-content/uploads/2024/01/Anatomy-of-the-diaphragm-original-illustration-1.png)
The foramen of Morgagni shown in the above picture (anteromedially) should obliterate normally. If it does not do so it results in congenital diaphragmatic hernia.
3 openings:
- IVC at T8 level
- Esophageal hiatus at T10 level
- Aortic opening at T12 level
Other structures passing through different openings in diaphragm:
- Caval hiatus: IVC and branches of right phrenic nerve
- Esophageal hiatus: esophagus, vagal trunks, esophageal branch of left gastric artery and left gastric vein
- Aortic hiatus: aorta, thoracic duct, azygous and hemiazygos vein
- Minor apertures (through crura): greater, lesser and least splanchnic nerves
Arterial supply:
![diaphragm blood supply](https://epomedicine.com/wp-content/uploads/2024/01/diaphragm-blood-supply.png)
- Major supply by right and left inferior phrenic artery (either as direct branch of aorta in 40% or from celiac trunk in 47%)
- Superior phrenic artery supplies posterior part of diaphragm
- Pericardiophrenic arteries- central area of diaphragm
- Others: musculophrenic and lower intercostal arteries
Venous drainage:
- Right inferior phrenic vein (IPV) directly drains into IVC
- Left IPV either drains directly to IVC or can drain to left suprarenal vein which in turn drains into left renal vein then to IVC
Nerve supply:
- Motor supply – right and left phrenic nerve which are divided as sternal, anterolateral and posterolateral branch
- Sensory supply:
- Central portion: phrenic nerve
- Peripheral: lower 5 intercostal and subcostal nerve
Embryological structures and their adult derivatives:
Embryonic structures | Adult derivatives |
Septum transversum | Central tendon of diaphragm |
Pleuroperitoneal membrane | Small peripheral part of diaphragm |
Dorsal mesentery of esophagus | Crura of diaphragm |
Mesoderm of body wall | Large peripheral part of diaphragm external to parts derived from pleuroperitoneal membrane |
Reference: Fischer’s mastery of surgery 8th edition
![Dr. Manoj Bhandari](https://epomedicine.com/wp-content/uploads/2024/01/Dr.-Manoj-Bhandari.jpg)
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