bi, all rights reserved, 2005 1 2b:normal anatomy of the trachea prepared by bronchoscopy...

BI, All Rights Reserved, 2005BI, All Rights Reserved, 2005 11

2B:2B: Normal Anatomy of The Normal Anatomy of The TracheaTrachea

Prepared ByPrepared ByBronchoscopy Bronchoscopy InternationalInternational

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BRONCHATLAS©

Series of Web-based Bronchoscopic Images


Tracheal and subglottic Tracheal and subglottic anatomyanatomy

The trachea is a cylindrical tube that projects onto the spine from C6 to the level of T5. As it passes downwards, it follows the curvature of the spine, and courses slightly backward. Near the tracheal bifurcation, it deviates slightly to the right.

The subglottis ends 2 cm below the level of the vocal cords. This corresponds cranially to the inferior margin of the cricoid cartilage, which is the inferior margin of the larynx and forms the only complete cartilage ring in the airway.


Tracheobronchial anatomyTracheobronchial anatomy

Tracheal Displacement Due to Goiter

Images downloaded from From www.vh.org


Anatomy of the tracheaAnatomy of the trachea

Length: 9-15 cmLength: 9-15 cm Outer diameter: 21-27 mmOuter diameter: 21-27 mm Internal diameter: 12-18 mmInternal diameter: 12-18 mm Distance infracricoid-carina about 11 cmDistance infracricoid-carina about 11 cm



18-22 cartilaginous rings18-22 cartilaginous rings There are 2.1 rings/cmThere are 2.1 rings/cm Becomes intrathoracic at 6Becomes intrathoracic at 6thth

cartilaginous ringcartilaginous ring Intrathoracic portion: 6-15 cmIntrathoracic portion: 6-15 cm



Cross-section area of Cross-section area of women about 40% less women about 40% less than men.than men.

From Oho and Matsukawa,

Olympus Co.


The membranous posterior membrane allows esophageal expansion during

deglutition

Contains glands, small

arteries, nerves, lymph

vessels and elastic fibers

Trachealis muscle overlies

esophageal muscle and epithelium


Tracheal dimensionsTracheal dimensionsTracheaTrachea Average cross-sectional Average cross-sectional

area of the male adult area of the male adult trachea is approximately trachea is approximately 2.8 cm22.8 cm2

Transverse (lateral)Transverse (lateral) diameter of 25 mmdiameter of 25 mm and and sagittal sagittal (anteroposterior) (anteroposterior) diameter of 27 mmdiameter of 27 mm are the are the upper limits of normal upper limits of normal (males) (males)

The lower limit of normal for The lower limit of normal for both transverse and sagittal both transverse and sagittal diameters is about diameters is about 13 mm in 13 mm in menmen and and 10 mm in women 10 mm in women


The average cross-sectional area of the The average cross-sectional area of the trachea trachea

in a 30-year-old male isin a 30-year-old male is

A.A. 1.5 cm1.5 cm22

B.B. 2.8 cm2.8 cm22

C.C. 3.2 cm3.2 cm22

D.D. 5.0 cm5.0 cm22

Click for correct answer: B


CricoidCricoid

Cricoid Cartilage

Cricothyroid membrane

Thyroid glandThyroid

cartilage

Cricoid cartilage


The carinaThe carina

Posterior

From the head

From the front

Posterior

Note vertical RMB


Main carina: Main carina: Concepts of anterior and Concepts of anterior and

posteriorposterior


Widened main carinaWidened main carina

Large subcarinal adenopathy

present

Posterior membrane


The cervical segment (extrathoracic) ends at the sternal manubrium and encompasses about the first six tracheal rings.

The U-shaped trachea is probably the most frequent shape found.

A man’s cross sectional tracheal area is usually about 40 percent larger than a woman’s.

In women, the lower limit of normal for transverse and sagittal diameters is about 10 mm.

Some facts about tracheal anatomy


Tracheal morphologiesTracheal morphologies

A saber-sheath or scabbard trachea is defined as a trachea with excessive transverse narrowing and widened sagittal diameter of the intrathoracic portion of the trachea. This is very different from the C-shaped trachea seen in about 49% of normal adults. The saber sheath trachea has been described in up to 5 % of elderly men.

Women tend to preserve a round configuration, while men tend to have some sagittal widening and transverse narrowing.


NORMAL Dynamic Airway NORMAL Dynamic Airway Collapse Collapse

During normal During normal respiration, there is respiration, there is narrowing of the narrowing of the airway caliber due to airway caliber due to bulging of the bulging of the posterior membrane.posterior membrane.

The mean decrease in The mean decrease in cross sectional area cross sectional area between inspiration between inspiration and expiration is up to and expiration is up to 40%.40%.

Click to continue

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Morphologic normal variantsMorphologic normal variants

U-shaped trachea (27%)U-shaped trachea (27%)

C-shaped trachea (49%)C-shaped trachea (49%)


Saber-sheath tracheaSaber-sheath trachea

Tracheal Index (TI) defined Tracheal Index (TI) defined as (transverse/saggital as (transverse/saggital diameter)<0.6diameter)<0.6

5% of elderly men with 5% of elderly men with COPDCOPD


Horseshoe tracheaHorseshoe trachea


Tracheal appearancesTracheal appearances

A

B

C

D

E

F

Saber sheath Dynamic collapse Crescent shape collapse

Normal shape expansion during inhalation circumferential collapse


Dynamic abnormalitiesDynamic abnormalities


TracheobronchomalaciaTracheobronchomalacia

A condition that causes the airways to narrow during exhalation because of weakness of the cartilaginous structures.

Crescent-Shaped TracheomalaciaClick to

continue



Excessive Dynamic Airway Excessive Dynamic Airway CollapseCollapse

Excessive bulging Excessive bulging of the posterior of the posterior membrane causing membrane causing narrowing of the narrowing of the cross-sectional cross-sectional area to 50% or area to 50% or more.more.

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Fixed abnormalitiesFixed abnormalities


Intraluminal disease and Intraluminal disease and extrinsic compressionextrinsic compression

Tumor invading Tumor invading through posterior through posterior wall.wall.

Tumor invading Tumor invading left and right left and right main bronchimain bronchi

Narrowing of Narrowing of lower third of lower third of tracheatrachea


ComplexComplexstenosisstenosis

Web-likeWeb-likestenosisstenosis

Courtesy C. Marquette

Simple and complex Simple and complex stricturesstrictures


Example of fixed stricture at Example of fixed stricture at previous tracheostomy siteprevious tracheostomy site

Note partial collapse of

anterior-lateral tracheal wall

Classic triangular shape of stomal

stricture


Measuring an abnormalityMeasuring an abnormality

1 2 3 4 5 6 7 8 9 10 11 12

First we measure the distance from the inferior aspect of vocal cords to the abnormality.

3.0 cm

Click to continue




1 2 3 4 5 6 7 8 9 10 11

1.5 cm

1 2 3 4 5 6 7 8 9 10 11 12

Next we measure the length of the abnormality itself

Click to continue




1 2 3 4 5 6 7 8 9 10 11

8.0 cm

1 2 3 4 5 6 7 8 9 10 11 12

Finally, we measure the distance from the distal extremity of the abnormality to the carina

Click to continue



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bi, all rights reserved, 2005 1 2b:normal anatomy of the trachea prepared by bronchoscopy...

Documents

scabbard trachea

normal anatomy

ushaped trachea

saber sheath trachea

male adult trachea

subglottic anatomythe

normal respiration

normal adults