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- 1. Gross Anatomy ofthe TRACHEA AND BRONCHI PROF. OLUWOLE AKINOLA
- 2. Learning Objectives At theend 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 theTrachea • 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 theTrachea 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 ofcervical 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 ofcervical 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 theThoracic 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 ThoracicPart 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 ofthoracic part of the trachea include: • Esophagus, • which lies directly behind it • Vertebral column and its anterior longitudinal ligament
- 13. Related to theright 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 ofthe 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 andLymphatic 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 theTrachea • 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 thetrachea: • 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 ofthe 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 ofthe 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
- 20. SURFACE PROJECTION OFTHE TRACHEA •
- 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
- 26. Left Principal Bronchus •Termination: •Divides into: • left superior lobar bronchus, & • left inferior lobar bronchus
- 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 lobarbronchus (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 LobarBronchus • 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 LobarBronchus • 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