TRACHEA AND THORACIC

DUCTDR GARIMA SEHGAL

TRACHEA

Organization and Functions of the Respiratory System

Upper respiratory tract (nose to larynx) and

Lower respiratory tract ( trachea onwards).

The Trachea windpipe

is a tubular passageway for air which extends as continuation of larynx

Is membrano-cartilaginous

MeasurementsLength - 12 cm External diameter 2.5 cm

Internal diameter adults – 12mm

newborn upto 3rd year- 3mm

Course –Begins – lower border of cricoid

cartilage/ C6 verterbraExtends through the mediastinum

and lies anterior to the esophagusAt the level of the sternal angle,

the trachea bifurcates into two smaller tubes, called the right and left primary bronchi.

• Each primary bronchus projects laterally toward each lung.• Level of Bifurcation

Cadaver -T4Living and

standing -T6Newborn – T3

Relations in the neck

Relations in thorax

Anterior and lateral walls supported by 15 to 20 C-shaped tracheal cartilages.

Posterior part of tube lined by trachealis muscle

The most inferior tracheal cartilage separates the primary bronchi at their origin and forms an internal ridge called the carina.

What is the benefit of not having complete rings of tracheal cartilage between the trachea and the esophagus?

Structure

Microscopic anatomy

Layers of the tracheal wall, from deep to superficial, are

(1) the mucosa, (2) the submucosa,(3) media, or

middle tunic, and (4) the adventitia.

Arterial supplymainly inferior thyroid arteries, bronchial arteries

Venous drainagemostly inferior thyroid veins

Lymphatic drainagepretracheal and paratracheal nodes

Nerve supplysensory, glands,trachealisparasympathetic (vagus)also sympathetic

Developmentthe respiratory systembegins as an outgrowth of the foregut just anterior to the pharynx.This outgrowth is called the respiratory diverticulum Soon after, the

tracheal bud divides into bronchial buds, which branch repeatedlyand develop with the bronchi.

As the respiratory diverticulum elongates, its distal end enlargesto form a globular tracheal bud, which gives rise to the trachea.

APPLIED ANATOMY

Tracheostomy

TOF

The trachea goes to the lungs. The esophagus and goes to the stomach. They run side-by-side through the neck and upper chest. During development a single tube divides to form the

esophagus and the trachea. sometimes the wall does not form properly and a tracheal

esophageal fistula and/or esophageal atresia may be the result.

THORACIC DUCT

Lymphatic System Consists of three parts

1. A network of lymphatic vessels (lymphatics)

2. Lymph

3. Lymph nodes

Lymphatic vessels begin as lymphatic capillaries.

Lymphatic capillaries are found throughout the body except in avascular tissues, the central nervous system, portions of the

spleen, and red bone marrow.

Is lymph more similar to blood plasma or to interstitial fluid? Explain your answer.

Lymph vessels (lymphatics) include:◦ Lymphatic capillaries◦ Lymphatic collecting

vessels◦ Lymphatic trunks and

ductsIf lymph flow

blocked = tissue swelling or edema

Specialized lymphatic capillaries in vili of small intestine transport lipids - they are called lacteals, and the fluid is called chyle.

Lymphatic vessels join to form lymphatic trunks.

Lymphatic trunks join to form lymphatic ducts.1)Thoracic duct 2)Right lymphatic duct

These empty into subclavian veins at junction with internal jugular vein.

Thoracic ductIs an elongated

common lymphatic trunk which conveys chyle and most of lymph of the body to the blood stream

Beaded in appearance

Has many valves

Length – 45 cmAverage width – 0.5

cm

CourseBeginning – at upper end of cisterna chyli at upper border of T12

• Enters thorax through aortic opening and traverses posterior mediastinum behind oesophagous

• Opposite T5 inclines left, runs upwardsTermination - at root of neck in the angle formed by junction of left subclavian and internal jugular vein

Relations

At aortic openingAt posterior

mediastinumIn superior

medistinumAt root of neck

Tributaries

Descending lymph trunks

Ascending lymph trunks

Left jugular lymph trunk

Left subclavian lymph trunk

Vessels draining upper six intercostal spaces

Drainage territoryDrains lymphatics

from whole of the body

except -the right side of Head and neck,-Right upper limb, -Right lung and thoracic wall-right half of heart- convex surface of liver

APPLIED ANATOMY

Thoracic duct laceration

is vulnerable to damage after thoracic surgery and particularly after oesophageal surgery

The incidence is between 0.2 and 3%Thoracic duct laceration is a potentially life-

threatening complication: mortality rates are more than 50% with conservative management and as high as 10-16% even after early surgical duct ligation.

Rupture leads to leakage of chyle, which is rich in lipid, protein and lymphocytes and hence a progressive nutritional and immune deficit occurs

Chylous effusions due to damage to some of the tributaries of the thoracic duct, rather than to the duct itself are usually self-limiting and respond to conservative treatment

May be obstructed by mature filarial parasites producing bursting of lymph vessels.

Causes collection of chylous fluid in pleural and peritoneal sacs , chylous hydrocele etc.