the clinically oriented anatomy of the trachea

the clinically oriented anatomy of the trachea

1. The anatomy of trachea By Dr. Soran M Karim

2. Contents Overview Structure, parts and anatomy Location and relations; Related structures ( trachea insitu ) Blood supply, lymphatic drainage and nerve supply Tracheo -bronchial tree Clinical aspects (C.O.A.)

3. References Clinical anatomy by regions, 10 th edition, Richard Snell's; chapter 12; pages 545-548 Netters atlas with clinical correlations 5 th edition, pages 200-216.

4. Before we start! The  respiratory  conducting passages is divided into the upper respiratory tract and the lower respiratory tract . The upper respiratory tract includes the  nose ,  pharynx , and  larynx . The lower respiratory tract consists of the  trachea ,  bronchial tree , and lungs . 

5. Overview Trachea  is a key part of your respiratory system .   A tube or system of tubes that carries air. A mobile cartilaginous and membranous tube ( Fibro-cartilaginous tube ), non- collapsable . Part of   lower respiratory tract (LRT) . It forms the trunk of the tracheobronchial tree. The trachea extends between the Neck  and  thorax , consisting of two parts;  cervical  and  thoracic.

6. Structure 16 rings of hyaline type ( 16-22 ). Roughly occupying the midline Stars as a continuation of larynx at C6; lower end of cricoid cartilage . Ends at Angle of Louie ( Carina ; cartilaginous ridge/ interior); VL; IVD T3 & T4 . Along with bronchi and bronchioles form TBT!

7. Structure cont.; Parts; Cervical : 1-5 th ring/ Thoracic : from 6 th ring down. The trachea is a D (or C shaped) in cross-section Tracheal  fibro- cartilaginous   anterolaterally and a fibro-muscular wall posteriorly. The posterior wall of the trachea is formed by the trachealis muscle, making the cartilages appear as (incomplete C-shaped rings). The mean angle of tracheal bifurcation is 60° (+/- 10° ). Variations!; age; gender; breathing!

8. Trachea insitu Anatomical position; Below Cricoid cartilage Beginning of TBT Travels between neck and superior mediastinum Ends at Manibrio -sternal joint C6-T4 Descends just anterior to esophagus; then inclines to right!

9. Measurements Measurements; L; 10 cm (9- 14 cm)/ dm ; 2.5 cm (2- 3 cm ). Dm = 2 cm in male vs 1.5 cm in females Length = 10-13 in male vs 9-10 cm in females The lumen is smaller in living human than cadavers! Cervical part = 7 cm Thoracic part = 3-5 cm

10. Constriction sites! At upper end; by thyroid gland lobes At lower end ; a. near bifurcation by the arch of aorta b. behind manubrium; by BCA

11. Relations with esophagus!

12. Relations of cervical trachea Anteriorly; Skin, fasciae , thyroid isthmus (R2-R4), ITV, JA, thyroid ima artery!?, lt. BCV, overlapped by sternothryoid & sternohyoid . Posteriorly; Right and left recurrent laryngeal nerve and esophagus. Laterally; Thyroid gland and carotid sheath.

13. The  carina of trachea is a cartilaginous ridge within the trachea that runs antero -posteriorly (sagittal/mid-sagittal) between the two primary bronchi at the site of the tracheal bifurcation at the lower end of the trachea.  Just 25 cm away from incisors and 30 cm away from nostrils! Becomes flattened when carcinoma spread through tracheo -bronchial L.N.

14. Importance of (Carina) Functional; Tracheal mucosa over carina is the most sensitive! Starts cough reflex to clear sputum Clinical/ Pathological; Useful landmark/ endoscopy/

15. Termination The tracheal bifurcation is the point at which the trachea divides into, and is continuous with, the two main or principal bronchi. Within the thorax at this point, the trachea is displaced slightly to the right by the arch of the aorta on its left. It ends in Carina at the level of the sternal angle - the inferior margin of the T4.

16. Tracheobronchial Tree

17. Blood supply and lymphatic drainage The upper 2/3rd ; supplied  by tracheal branches of inferior thyroid arteries , that stem from the  thyrocervical trunk .  Lower 1/3rd ; receives blood from bronchial arteries Venous blood is drained to the inferior thyroid venous plexus, which empties into the  brachiocephalic veins , Azygos and hemiazygos veins. Lymphatic drainage  is to the pretracheal and paratracheal (cervical, thoracic) lymph nodes that empty into the  deep cervical lymph nodes .

18. Nerve supply The trachea receives innervation from the; Parasympathetic  supply originates from Vagus nerve via; the recurrent laryngeal nerves; secreto -motor and sensory to MM and motor to trachialsi !   Sympathetic  supply is provided by the sympathetic trunks (middle cervical sympathetic ganglion); vasomotor

19. Clinical correlations!

20. A tracheostomy ;is an opening surgically created through the neck into the trachea (windpipe) to allow air to fill the lungs. The ideal location for placement of the tracheostomy tube is between the R2-R3 . Palpate the neck to identify key anatomical landmarks. These include the thyroid cartilage, the cricoid cartilage, and the sternal notch.

21. Tracheostomy vs Tracheotomy The term “ tracheotomy ” refers to the procedure to make an incision (cut) into the trachea (windpipe). The temporary or permanent opening itself is called a “ tracheostomy .” However, the terms are sometimes used interchangeably.

22. Tracheomalacia In tracheomalacia , the tracheal cartilages become abnormally soft. As a result, they cannot maintain the trachea open and it continuously collapses during inspiration and expiration . The affected area can span only a few cartilages or affect the entire trachea. Being a congenital anomaly, the tracheomalacia manifests in early infancy. It presents with signs and symptoms of respiratory distress such as dyspnea, cough, stridor, wheezing and tachypnea.

23. TEF / tracheoesophageal fistula Esophagus (the tube that connects the throat to the stomach) Trachea (the tube connecting the throat to the windpipe and lungs ) They are separate. A ( TEF ) is  an abnormal connection between these two tubes . Most common congenital anomaly Direct surgical management!

24. What is Tracheal Stenosis?  Tracheal stenosis is the narrowing of the trachea (gets in the way of normal breathing). Symptoms of this condition can vary from very mild to severe, but the condition is treatable. There are two types of tracheal stenosis: Present since birth (congenital), which is rare Caused by an injury or illness (acquired)

25. TBT! The right main bronchus is shorter, wider and courses almost vertically compared to the left one. Therefore, it is more susceptible to foreign body obstructions.

26. Tracheoscopy ; A small procedure usually performed by an ENT surgeon to look at the trachea in more detail. An endotracheal tube is a flexible tube that is placed in the trachea (windpipe) through the mouth or nose.  

27. Summary; Intro; trachea? Structure and Functions Location , measurements and related structures ? Parts and vertebral levels Blood supply, lymphatics and nerve supply

28. Upcoming lecture; next week Lungs and pleural cavities Clinical anatomy by region Chapter 4 ; pages 192-217

29. Questions?

30. Quiz time ! Why foreign bodies lodge into the right main bronchus! Why trachea needs hyaline cartilage in the composition of its structure while esophagus doesn't!?