Diaphragm (Viva)

Q.1 What is the origin of diaphragm?

Arise from the periphery, in three parts:

• Sternal: Back of the xiphoid process.
• Costal: Inner surfaces of cartilages and adjacent parts of lower six ribs.
• Lumbar: Medial and lateral lumbocostal arches and from lumbar vertebrae by right and left crura.
  
  

Q.2 What are lumbocostal arches?

These are tendinous arches in the fascia covering the muscles in the posterior abdominal wall, e.g. medial lumbocostal arch (medial arcuate ligament) in fascia over the upper part of psoas major and lateral lumbocostal arch (lateral arcuate ligament) in fascia over the upper part of quadratus lumborum.

Q.3 What is the origin of the crus of the diaphragm?

Right crus: From anterolateral surface of body of L1,2,3.

Left crus: From anterolateral surface of body of L1,2.

The medial margins of two crura join to form the median arcuate ligament.

Q.4 What is the insertion of muscle fibers of the diaphragm?

Trilobed central tendon, which lies below and is fused to the pericardium.

Q.5 What is the nerve supply of diaphragm?

Motor: Phrenic nerve (C3,4).

Sensory:

– Phrenic nerves: Central part.
– Lower six thoracic nerves: Peripheral part.

Q.6 What are the other structures supplied by the phrenic nerve?

 Sensory fibers to:

• Pleura: Mediastinal and diaphragmatic.
• Pericardium: Fibrous and parietal layer of serous pericardium.
• Peritoneum: Below the central part of the diaphragm.
• Through coeliac plexus to falciform and coronary ligaments of the liver, gallbladder, suprarenals, and inferior vena cava.
  
  

Q.7 What are the functions of the diaphragm?

• Separates the thoracic and abdominal cavity.
• Principal muscle of inspiration.
• In all expulsive acts, e.g. sneezing, coughing, vomiting, defaecation, etc. It provides additional power to each effort.
  
  

Q.8 What are the variations in the position of the diaphragm with posture?

Level of diaphragm is:

• Highest in supine position.
• Lowest in sitting position.
• Midway in standing.

Q.9 Name the structures passing through the opening of the diaphragm.

• Caval opening (T8):
  Slightly to the right of the median plane in the central tendon.
  Transmits inferior vena cava and half of the right phrenic nerve.
  
  
• Oesophageal opening (T10):
  Slightly to the left of the median plane.
  Transmits esophagus, right and left vagi, oesophageal branches of left gastric artery with accompanying veins.
  
  
• Aortic opening (T12): Central.
  Transmits (from right to left) vena azygous, thoracic duct, and aorta.
  Aortic opening is deep to median arcuate ligament.
  
  
• Smaller orifices in diaphragm:
  – Between xiphoid slip and that from 7th cartilage:
  Superior epigastric vessels.
  
  – Between slips from 7th and 8th costal cartilages:
  Musculophrenic vessels. Also transmits 7th intercostal nerve and vessels.
  
  – Between each pair of remaining slips:
  One of the lower five intercostal nerves and vessels.
  
  – Behind lateral lumbocostal arch:
  Subcostal nerve and vessels.
  
  – Behind medial lumbocostal arch: Sympathetic trunk.
  
  – Each crus:
  Greater, lesser and least splanchnic nerve. Left crus in addition is pierced by vena hemiazygous.
  
  – Muscular part of diaphragm to the left of anterior folium of central tendon:
  Left phrenic nerve
  
  

Q.10 Why irritation of diaphragm causes pain in shoulder tip?

Because phrenic nerve and supraclavicular nerves have the same root value, i.e. C3,4.

Q.11 What is ‘eventration’ of diaphragm?

This is a congenital defect, in which the high position of the diaphragm occurs due to the replacement of the left half of the diaphragm by a fibrous membrane.

Q.12 What is foramen of Morgagni?

Also called space of Larry. It is a space between the xiphoid and the costal origins of diaphragm.

Site of congenital hernia. More common on the right side.

Q.13 What is foramen of Bochdalek?

This is the commonest site of congenital diaphragmatic defects in the periphery of the diaphragm in the region of the 10th and 11th ribs attachment.

Defect is in the posterolateral part of the dome on the left side of the diaphragm resulting from the failure of closure of pericardiopleural canal.

Q.14 What is the development origin of diaphragm?

Diaphragm is developed from:

• Septum transversum
• Pleuroperitoneal membrane
• Ventral and dorsal mesenteries of esophagus
• Mesoderm of body wall.

 

Q.15 What is the diaphragm? What are its attachments?

The diaphragm is a large muscle which forms a partition between the cavities of the thorax and abdomen origin.

The origin of the diaphragm can be divided into sternal, costal, and lumbar vertebral parts.

The sternal part consists of two slips: right and left which arise from the back of the xiphoid process. The costal part consists of broad slips one from the inner surface of each of the lower six ribs (7th to 12th) and their costal cartilages.

The lumbar part consists of two crura (right and left) that arise from the anterolateral aspects of the bodies of lumbar vertebrae and of fibers that arise (on either side) from tendinous arches called the lateral and medial arcuate ligaments. The right crus is larger than the left; it crusis from the bodies of vertebrae L1, L2, and L3 and from the intervening intervertebral discs. The left crus similarly arises from vertebrae L1 and L2.

Insertion:
From its extensive origin, the muscular fibers of the diaphragm run upwards and converge to the inserted on the margins of a large, flat, central tendon, which is located just below the pericardium and heart.

Q.255 Describe the apertures present in the diaphragm.

The apertures present in the diaphragm are as follows

• The aortic aperture:
  The aperture lies behind the medial arcuate ligament and in front of the disc between T12 and L1. The aorta, therefore passes behind the diaphragm rather than through it.
  
  
• The aperture for esophagus:
  This is situated at the level of the 10th thoracic vertebrae.
  The esophageal aperture also transmits the right and left gastric nerves.
  
  
• The aperture for inferior vena cava lies in the central tendon at the level of the eighth thoracic vertebra.
  The vena caval opening also transmits the whole or part of the right phrenic nerve.
  
  
• The left phrenic nerve passes through the muscular part of the diaphragm, to the left of the anterior column of the central tendon.
  Numerous small veins also pass between the thorax and abdomen through small apertures in the central tendon.
  
  
• There are a number of small apertures present around the periphery of the diaphragm, in gaps between various slips of origin.

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