2. Learning Objectives
At the end of the lecture, you should be able to:
• Describe the basic anatomy of the trachea
• Describe the basic anatomy of the different divisions of bronchi
• Describe the clinical anatomy of the trachea and bronchi
3. Resource Materials
• Textbooks
• Clinically-Oriented Anatomy, Keith L Moore
• Clinical Anatomy, Harrold Ellis
• Grant’s Atlas of Anatomy, by Anne Agur & Arthur Dalley
• Atlas of Human Anatomy, by Frank Netter
• Highlights of Human Anatomy, Akinola & Dosumu. Available online at
https://www.researchgate.net/publication/325870666_highlights_of_human
_anatomy
• Cadaveric dissection
• Museum specimens
4. TRACHEA (WIND PIPE)
• A cartilaginous/fibromuscular tube that
connects larynx to main bronchi
• Location: partly in the neck; partly in the
thorax
• mainly a midline structure
• though it deviates to the right near its termination
• Origin:
• lower border of the cricoid cartilage (at C6);
• Termination:
• at the sternal angle of Louis (T4/T5)
• It may reach as far down as T6 in deep inspiration;
and T4 in expiration
• partly owing to its ability to extend
5. Tracheal cartilages • 16–20 C-shaped rings of hyaline
cartilage
• Keep trachea patent
• Concavity of cartilages face
posteriorly
• Possesses no cartilages in its
posterior part
• Here, it adjoins esophagus
• This allows esophagus to expand
during deglutition
• The last cartilage is keel-like, and
is referred to as carina
• Its deviation from midline suggests
metastases in the
tracheobronchial nodes
6. Dimensions of the Trachea
• Length:
• at birth: 4 cm
• In adult: 9-15 cm
• External diameter:
• 2 cm in adult males
• 1.5 cm in adult females
• Internal diameter:
• 0.3 cm in infants
• 1.2 cm in adults
• Internal diameter (in mm)
corresponds to age (in years)
during childhood
• Wider in cadavers than in the
living
7. Relations of the Trachea
Anterior Relations of Cervical Part:
• Isthmus of thyroid gland
• lies transversely across 2nd-4th tracheal rings
• Remains of thymus, jugular arch,
• Muscles: sternothyroids and
sternohyoids,
• Fascia:
• Pretracheal fascia
• below the isthmus of thyroid gland
• superficial and investing layers of cervical
fasciae, and the skin
• Inferior thyroid vein and (occasionally)
thyroidea ima artery
• below the level of isthmus of thyroid gland
• Arterial anastomoses formed by the
superior thyroid arteries,
• just above the isthmus of thyroid gland.
• Tracheal lymph nodes
• that drain the trachea and adjoining
structures
8. Posterior relations of cervical part of the trachea include:
• Cervical part of the esophagus,
• which lies directly behind it
• Recurrent laryngeal nerves
• in the groove between esophagus
and trachea
• Some branches of inferior
thyroid artery
• Vertebral column
9. Lateral Relations of cervical part of the trachea
• Right and left lobes of thyroid gland
• Each lobe reaches as far down as level
of the 5th or 6th tracheal ring
• Carotid sheath
• located posterolateral to the lobe of
thyroid gland, and
• contains common carotid artery,
internal jugular vein & vagus nerve
• Inferior thyroid artery
• ascends from the thyrocervical trunk
10. Relations of the Thoracic
Part of the Trachea
Anterior relations of the thoracic part:
• Manubrium sterni,
• bounds superior mediastinum
anteriorly
• Lower part of inferior thyroid vein
• which drains the upper part of the
trachea
• Aortic arch
• Brachiocephalic trunk and left
common carotid artery.
• These arise from the aortic arch
• Left brachiocephalic vein
• This which crosses to the right of the
midline,
• where it joins the right brachiocephalic
vein to form SVC (behind the right 1st
costal cartilage)
11. Relations of the
Thoracic Part of the Trachea
Anterior relations of trachea
(thoracic part):
• Remains of the thymus
• Deep cardiac plexus of nerves
• This lies anterior to tracheal
bifurcation
• Some lymph nodes
• into which the trachea and
adjacent structures drain
• Origins of sternothyroids &
sternohyoids
12. Posterior relations of thoracic
part of the trachea include:
• Esophagus,
• which lies directly behind it
• Vertebral column and its
anterior longitudinal ligament
13. Related to the right of the thoracic part of the trachea are:
• Right pleural cavity
• Right lung
• Superior vena cava (SVC)
• This enters the right atrium at the level of the
right 3rd costal cartilage
• Right brachiocephalic vein
• which joins the left vein at the level of the right 1st
costal cartilage, to form the SVC
• Azygos vein
• ascends over the vertebral column, on the right of
midline
• It ends by arching forwards over the right root of
the lung, to join the SVC at the level of the right
2nd costal cartilage
• Right vagus nerve, which descends behind
the right root of the lung
14. Left relations of the thoracic part of the
trachea include: • Aortic arch
• Passes backwards to the lower border of
T4, where it continues with descending
aorta
• Left recurrent laryngeal nerve
• This curves backwards, round the aortic
arch, to ascend to the neck
• between trachea and esophagus
• Left subclavian artery
• which arises from aortic arch
• Left common carotid artery
• which ascends to the neck, from the
aortic arch
15. Blood Supply and Lymphatic Drainage of the
Trachea • Arterial supply:
• inferior thyroid arteries
• These are branches of the thyrocervical trunks
• bronchial arteries
• These arise from descending thoracic aorta,
and supply the lower part of the trachea
• Venous drainage:
• inferior thyroid veins
• which join the respective brachiocephalic
veins; however, these veins may unite to form
a single vein that usually ends in the left
brachiocephalic vein
• Lymphatic Drainage: paratracheal and
pretracheal nodes
16. Innervation of the Trachea
• Sensory fibres: recurrent
laryngeal nerves
• These supply its mucosa
• Parasympathetic fibres: vagus
nerves
• these are secretomotor to
tracheal glands
• Sympathetic fibres: from
sympathetic chain
• produce vasoconstriction of
tracheal vessels, thereby
reducing the secretory activity
of tracheal glands
17. •Compression of the trachea:
• trachea may be constricted in
double aortic arch and aortic
aneurysm
• Tracheal tug (or Oliver’s sign)
is seen in aortic aneurysm
• Xrized by abnormal descent
of the trachea during systole
• Enlargement of thyroid gland,
thymus, or malignant nodes
may also compress trachea
Applied Anatomy of the Trachea:
Tracheal Compression & Tracheal Tug
18. Applied Anatomy of the Trachea:
Tracheotomy & Tracheostomy
• When larynx is obstructed, tracheotomy
may be performed
• By midline incision of the trachea midway btw
thyroid cartilage and suprasternal notch
• A tube could then be introduced to enhance
ventilation (tracheostomy)
• Greater risk is associated with a low
tracheotomy
• owing to the possibility of bleeding from
inferior thyroid vein, thyroidea ima artery
(when present); left brachiocephalic vein or
brachiocephalic trunk (in children)
• Common carotid artery and recurrent
laryngeal nerves are at risk during
tracheotomy
19. Applied Anatomy of the Trachea: Bronchoscopy
• Biopsies may be taken
and the interior of the
trachea examined
during bronchoscopy
• Carina can be seen
• Foreign bodies and fluid
may also be removed
from the trachea using
a bronchoscope
21. Bronchi
Bronchi exist as:
• Principal bronchi
• arise from the trachea
• at the level of the
sternal angle
• Secondary or lobar
bronchi
• arise from the principal
bronchi and
• supply the lobes of the
lungs
• Tertiary or segmental
bronchi
• arise from the
secondary bronchi and
• supply
bronchopulmonary
segments
• Series of smaller tubes
that branch repeatedly
to supply the lungs
22. Right Principal Bronchus
• Shorter, wider & more
vertically-disposed than
left principal bronchus
• Forms an angle of 1550
with the trachea
• Length: 2.5 cm
• half the length of the left
principal bronchus
• Gives off a right superior
lobar (eparterial)
bronchus before it
reaches the hilum of
right lung
• Termination; by diving
into:
• middle lobar bronchus,
and
• inferior lobar bronchus
• at the hilum of the right
lung
23. Right Principal Bronchus
• Anterior Relations:
• SVC, ascending aorta,
right pulmonary artery
and veins
• Superior Relation:
• Arch of the Azygos vein
• Clinical Anatomy:
• Is the more common site
for the lodgment of
objects that enter the
trachea
• Is easier to approach
surgically than the left,
which is closer to the
aorta
24. Left Principal Bronchus • Narrower and
longer than right
principal bronchus
• Length:
• 5 cm in length
• double the length
of the right one
• Makes an angle of
1350 with the
trachea
• Thus, it is more
transversely-
disposed than the
right one.
25. Left Principal Bronchus • Enters the root of the left
lung opposite T6
vertebra
• Posterior Relations:
• esophagus (at T5),
• thoracic duct, and
• descending thoracic
aorta.
• Superior Relations:
• aortic arch
• Left pulmonary artery
• Lies initially behind and
then below the left
pulmonary artery
• Is situated behind and
just above the plane of
the transverse sinus of
the heart
27. Secondary (Lobar) Bronchi • Arise from the primary
bronchi
• Usually 3 on the right and
2 on the left
• Enter the lungs through
the hila
• Here, they all lie below the
pulmonary arteries, except
the eparterial bronchus,
• that enters hilum above
the right pulmonary artery
• Each supplies a lobe of the
lungs
• Here, each ends by dividing
into series of smaller tubes
called segmental (or
tertiary) bronchi
28. Right superior lobar bronchus
(Eparterial bronchus)
• Origin:
• Lateral aspect of the right
principal bronchus
• it passes superolaterally,
above the right pulmonary
artery
• Is the highest-placed
structure in the hilum of
the right lung
• Ends about 1 cm from its
origin by dividing into 3
segmental bronchi:
• Apical segmental bronchus
• Anterior segmental
bronchus, and
• posterior segmental bronchi
• These supply the respective
bronchopulmonary
segments of the superior
lobe of the right lung
29. Middle Lobar Bronchus • Origin:
• Anterior aspect of the right
principal bronchus,
• 2 cm distal to the origin of
eparterial bronchus
• Passes anterolaterally to
the middle lobe of the
right lung
• Termination:
• Divides into medial and
lateral segmental bronchi,
• that supply the respective
bronchopulmonary
segments of the middle
lobe of the right lung
30. Right Inferior Lobar Bronchus
• Origin:
• the continuation of the right
principal bronchus
• beyond the origin of the
middle lobar bronchus
• Termination: divides into
• Superior segmental
bronchus,
• medial basal segmental
bronchus,
• lateral basal segmental
bronchus,
• anterior basal segmental
bronchus, &
• posterior basal segmental
bronchus
• supply the respective
bronchopulmonary segments
of the inferior lobe of the
right lung.
31. Left Superior Lobar Bronchus • Origin:
• from the anterolateral part of the
left principal bronchus
• Has two main divisions:
• upper and lower (lingular)
divisions.
• these correspond to the right
superior and middle lobar bronchi
respectively.
• Supplies the apical, anterior and
posterior bronchopulmonary
segments of the superior lobe of
the left lung (thro its upper div.)
• Apical and posterior segmental
bronchi could be fused as
apicoposterior segmental
bronchus
• Also supplies the superior and
inferior lingular
bronchopulmonary segments (of
the lingula) of the superior lobe
of the left lung
• through its lower (lingular) division
32. Left Inferior
Lobar Bronchus
• Is the continuation of the left
principal bronchus
• Divides in the same manner as does
the right inferior lobar bronchus
• Gives rise to the left superior
segmental bronchus from its
posterior aspect
• This supplies superior
bronchopulmonary segment of the left
inferior lobe
• Also gives rise to the left anterior
basal and medial basal segmental
bronchi (via a common stem)
• They may be fused as anteromedial basal
bronchus
• These supply bronchopulmonary
segments of the same name
• Is also the source of the left posterior
basal and lateral basal segmental
bronchi
• They supply bronchopulmonary
segments of the same name in the
inferior lobe of the left lung
33. • Each segmental (tertiary) bronchus divides repeatedly and
dichotomously;
• producing several (>20) generations of intrasegmental bronchi; and eventually
smaller tubes devoid of cartilage termed bronchioles
• Bronchioles include terminal and respiratory bronchi.
• Respiratory bronchioles supply alveolar sacs
