Trachea, bronchial tree and lungs

complete

what is the trachea in basic terms?

a tube that conducts air from the larynx to bronchi

how long is the trachea in cm?

10-11cm

what is the diameter of the trachea?

2.5cm

what vertebral levels does the trachea run between?

C6 to T4/5

what exists anteriorly of the trachea?

C shaped cartilage rings

what is found of the trachea posteriorly?

a smooth muscle called trachealis which controls the diameter

what connects the first tracheal cartilage with the cricoid cartilage?

the cricotracheal membrane

which part of the mediastinum does the trachea exist in?

the superior mediastinum

what is posterior to the trachea?

the oesophagus

what is found anterior to the trachea?

•Thyroid gland isthmus

•Brachiocephalic trunk, L brachiocephalic vein

•Cardiac plexus nerves (sympathetic and parasympathetic)

•Tracheobronchial nodes

•Manubrium (manubriosternal joint also marks bifurcation of trachea)

•Inferior thyroid vein

•Sternothyroid, sternohyoid

which cartilage ring is palpable?

1st ring

what obscure cartilages 2-4?

the thyroid gland

what is found lateral to the trachea?

•Thyroid gland lobes

•Parathyroid glands

•Common carotid arteries

•Aortic arch, common carotid and subclavian artery (L)

•Azygous arch, Vagus nerve (R)

what is found posterolateral to the trachea?

recurrent laryngeal nerves

what arteries supply the trachea?

• inferior thyroid artery

• bronchial arteries

what does the trachea drain to (venous)?

• inferior thyroid vein

• bronchial veins

what does lymph drain to from trachea?

pre and para tracheal nodes

what nerves supply the trachea?

pulmonary plexus

• sympathetic - sympathetic trunk via cardiopulmonary splanchnic nerves

• parasympathetic - vagus nerve

which vertebral levels of nerves supply the trachea?

C4-T5

what are the sympathetic effects on the trachea?

dilation and reduced secretion

what are the parasympathetic effects on the trachea?

constriction and secretomotor

which division of bronchi are lobar bronchi?

secondary

how many lobar bronchi are found in each lung?

right - 3

left - 2

which division of bronchi are segmental bronchi?

tertiary

what do bronchi receive blood from?

bronchial arteries

how many bronchial arteries supply each lung?

right - 1

left - 2

how many generations of bronchioles are there?

20-25

what follows bronchioles in terms of division?

respiratory bronchioles → alveolar ducts → alveolar sacs

what happens to the cartilage of the trachea with age?

it ossifies

what epithelium lines the trachea?

respiratory - ciliated, pseudostratified, columnar epithelium

do bronchioles have cartilage?

no

what are club cells?

non ciliated cuboidal epithelium that produce protective secretions

what were club cells formerly known as?

Clara cells

where can club cells be found?

in epithelium of bronchioles

what are the functions of the lungs?

• primarily gas exchange

• pH balance

• other metabolic functions - angiotensin 1 to angiotensin 2

• prostaglandin synthesis

what separates the lobes of the lungs?

fissures

what are the surfaces of the lungs?

costal, mediastinal, diaphragmatic

what are the segments of the right and left superior lobes?

• apical

• posterior

• anterior

what are the segments of the right and left inferior lobes of the lungs?

• superior (apical)

• anterior basal

• posterior basal

• medial basal

• lateral basal

what are the segments of the right middle lobe?

• lateral

• medial

what are the additional segments of the left superior lobe?

• superior lingular

• inferior lingular

what shape are segments?

pyramidal with apices converging towards hilum

what separates the different segments of the lung?

septa

can veins and lymphatics cross septa between segments of the lungs?

yes

what is the root of the lung covered by?

pleural sleeve which also extends inferiorly as pulmonary ligament

what does the root of the lung contain?

•Main bronchus

•Pulmonary artery (deoxygenated blood to lung)

•Pulmonary veins (oxygenated blood to heart)

•Bronchial arteries – supplying bronchi and structural tissue of lung

•Bronchial veins

•Lymph nodes and vessels

what do bronchial arteries supply?

tissue of respiratory system

what do the two left bronchial arteries branch from?

the aorta

what does the right bronchial artery branch from?

3rd intercostal artery

what is the most superior structure of the hilum?

pulmonary arteries

describe the diameter and pressure of pulmonary arteries.

large diameter, low pressure

which is shorter, the left or right pulmonary artery?

left

what veins drain the lungs?

• bronchial

• pulmonary

what do the bronchial veins drain to?

• azygous (R) or hemiazygous (L)

• or enter pulmonary circulation and return to the heart

how many pulmonary veins are there on each side?

two

aside from airways, what else does the pulmonary plexus supply?

visceral pleura

which part of the pulmonary plexus is larger - anterior or posterior?

posterior

what is the flow of lymph from subpleural plexus?

sub pleural plexus → intrapulmonary nodes → hilar nodes → tracheobronchial nodes (sup and inf) → paratracheal nodes → bronchomediastinal trunks

what do inferior/carinal nodes drain?

the lower lobes of both lungs, primarily draining to the right side

what are clinical considerations for the lungs?

Asthma

COPD

Cancer

Foreign body aspiration

Pneumothorax/haemothorax

Pleurisy

Cystic fibrosis

Bronchoscopy

Tracheostomy

Pulmonary embolism

what can be causes of asthma?

• allergic

• non allergic

• occupational

what is salbutamol?

a B2 adrenoreceptor agonist - relaxes bronchial smooth muscle

how many people have asthma in the UK?

more than 8 million

what is the biggest risk factor for COPD?

smoking

what occurs in COPD?

mucus hyper secretion and alveolar destruction

what are the two conditions that make up COPD?

emphysema or chronic bronchitis

what percentage of primary lung tumours does bronchial carcinoma make up?

95%

how do metastases to the lung often happen?

lymphatic spread

what is mesothelioma - affecting pleura, often caused by?

asbestos

what is a tumour in the apical lobe called?

pan coasts tumour

what nerve compression can a pancoasts tumour cause?

• sympathetic trunk above T4

• brachial plexus

what does the compression of the sympathetic trunk above T4 cause?

Horner’s syndrome (oculosympathetic paresis)

what is pneumothorax?

air in pleural cavity

what can cause pneumothorax?

• spontaneous (tall, thin, male)

• higher risk in certain syndromes

• penetrating chest injury

what can be causes behind infective pneumonia?

• bacterial

• viral

• fungal

what is a risk factor for pneumonia?

lying supine

what type of genetic condition is cystic fibrosis?

autosomal recessive (1 in 2000)

what is the mechanism of cystic fibrosis?

mucous is too thick due to abnormal ionic composition (malfunctioning chloride transporter)

why do foreign body aspirations have a tendency to the right main bronchus?

wider, shorter, more vertical

what is done to visualise or retrieve a foreign body aspiration?

bronchoscopy

what is a pulmonary embolism?

blockage occurring in pulmonary artery

what can a pulmonary embolus be made up of?

fat, air, tumour

what are risk factors for pulmonary embolism?

• immobilisation

• recent surgery

• malignancy

• paralysis

• smoking

• obesity

what is a tracheostomy?

a non emergency procedure where a hole is cut in 2nd and 3rd tracheal rings

is sedation required for bronchoscopy?

yes

what is the difference between a cricothyroidotomy and a formal tracheostomy?

• CT - live saving, anaesthetic not needed

• T - full anaesthetic