Comparison between tract and nerve

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  Comparison between tract and nerve Nerve Nerve contain bundle of axons (nerve fibers) in the peripheral nervous system (PNS) that transmits signals between the central nervous system (CNS) and other parts of the body. It is the most important part of peripheral nervous system Location: Peripheral nervous system. Structure: Made of axons, connective tissue layers (endoneurium: axon is surrounded by it , perineurium: bundle of axons are surrounded by it, epineurium: whole nerve trunk is surrounded by it), and blood vessels. It gets myelination by Schwann cell   Function: Carries sensory signals to the CNS (afferent) from peripheral part of body or motor signals carry from from the CNS (efferent) to target organs like skeletal muscle, cardiac muscle, smooth muscle or glands Example: Sciatic nerve, median nerve, except optic nerve (though optic nerve is technically part of CNS in develop...
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Difference between right principal bronchus and left principal bronchus : lecture notes

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Difference between right principal bronchus and left principal bronchus

Right principal bronchus

Left principal bronchus

Shorter and wider

Longer and narrower

It is approximately 2.5 cm long

The mean±SD luminal diameter of the right principal bronchus was 1.41±0.23,

The mean diameter of the left main bronchus (LMB) was 11.6±1.9 mm.

More vertically place within the body

More horizontal than the right

it divides into bronchi before it enter within the hilum

it divides into bronchi after enter within the hilum

It forms 20-30 degree angle

It forms 40-60 degree angle

It enter the hilum at the level of verterbra T5

It enter the hilum at the level of verterbra T6

It gives off three secondary bronchus for three lobe of right lung

It gives off two secondary bronchus for two lobe of left lung

The right pulmonary artery  lies initially below the right bronchus and then later in front of it.

The left pulmonary artery is found lying initially above the left main bronchus, then later in front of it.

the azygos vein arches over the right main bronchus from behind.

Passes underneath the aortic arch, and crosses in front of the esophagus, the thoracic duct, and the descending aorta.
Relations

At right pulmonary hilum:

  • superiorly: arch of azygos vein
  • inferiorly: right pulmonary veins
  • anteriorly: right pulmonary artery (pulmonary veins anterior to pulmonary arteries)
  • posteriorly: esophagus (azygos vein posterior to esophagus)

 

Relations

At left pulmonary hilum:

  • superiorly: left pulmonary artery (aortic arch superior to pulmonary artery)
  • inferiorly: left pulmonary veins
  • anteriorly: left pulmonary veins
  • posteriorly: descending thoracic aorta

 

Left main bronchus is supplied by two arteries, superior and inferior left bronchial arteries directly arising from the descending aorta

Right main bronchus is supplied by one single right bronchial artery  It arises from one of the following origins:

  • proximal part of one of the upper posterior intercostal arteries (commonly right third posterior intercostal artery)
  • a common trunk with the left superior bronchial artery
  • the descending aorta

 
  • right bronchial vein drain into the azygos vein

Left bronchial vein drain into the accessory hemiazygos vein

 















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