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Anatomy of the respiratory tract
The respiratory tract includes the mouth, nose, pharynx, larynx, trachea, bronchi and lungs. The nose contains nasal cavities lined with hairs and mucus to warm and filter air. It connects to the nasopharynx and paranasal sinuses. The pharynx consists of the nasopharynx, oropharynx and laryngopharynx and contains the tonsils. The larynx, or voice box, contains vocal cords and cartilage that support the airway and allow for sound production. It connects to the trachea and lungs.
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Anatomy of the respiratory tract
- 1. Anatomy of the respiratorytract Presentation by: Dr. Himanshu Jangid
- 2. DIVISIONS OF THE RESPIRATORYSYSTEM • MOUTH • NOSE AND NASAL CAVITIES • PHARYNX • LARYNX • TRACHEA AND BRONCHIAL TREE • LUNGS AND PLEURAL MEMBRANES • Alveoli
- 3. MOUTH • The vestibule:formed by the lips and cheeks without and by the gums and teeth within. • The mouth cavity:bounded by the alveolar arch of the maxilla and the mandible, and teeth in front, the hard and soft palate above, the anterior two-thirds of the tongue and the reflection of its mucosa forward onto the mandible below, and the oropharyngeal isthmus behind.
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- 5. MOUTH • The palate: •The hard palate is made up of the palatine processes of the maxillae and the horizontal plates of the palatine bones. • The soft palate hangs like a curtain suspended from the posterior edge of the hard palate. Its free border bears the uvula centrally and blends on either side with the pharyngeal wall. • Palatine aponeurosis: tough fibrous sheet, the ‘skeleton’ of the soft palate.
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- 7. MOUTH • The musclesof the soft palate: • the tensor palati, • the levator palati, • palatoglossus, • palatopharyngeus • musculus uvulae
- 8. NOSE • External nose:is formed by • The nasal bones. • The nasal part of the frontal bones. • The frontal processes of the maxillae. • A series of cartilages in the lower part. • A small zone of fibro-fatty tissue that forms the lateral margin of the nostril (the ala). • The cartilage of the nasal septum comprises the central support of this framework.
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- 12. NOSE • The cavityof the nose: • Subdivided by the nasal septum into two quite separate compartments. • Open to the exterior by the nares and into the nasopharynx by the posterior nasal apertures or choanae. • Immediately within the nares is a small dilatation, the vestibule, which is lined in its lower part by stiff, straight hairs.
- 13. NOSE • Little’s area:Thesphenopalatine branch of the maxillary artery ---------------> with the septal branch of the superior labial branch of the facial artery -----------> epistaxis occurs in some 90% of cases (Little’s area).
- 14. NASAL CONCHAE • Superiorand middle nasal conchae – Part of the ethmoid bone • Inferior nasal conches – Separate bone • Project medially from the lateral wall of the nasal cavity • Particulate matter – Deflected to mucus-coated surfaces
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- 17. NASAL INTUBATION CAUTIONS Occasionally, the posterior end of the inferior turbinate may be hypertrophied ---->resistance . The delicate mucosa of the nose and the posterior pharyngeal wall may easily be torn, and force must never be used in this manoeuvre. Cases are on record of nasal tubes being passed through the mucosa of the posterior pharyngeal wall into the retropharyngeal space and of serious haemorrhage from injury to the posterior ethmoidal vessels, which are branches of the internal carotid artery via the ophthalmic artery and therefore impossible to control by proximal ligation.
- 18. MAGILL’S FORCEPS FORNASAL INTUBATION • A nasotracheal tube must curve anteriorly as it passes through the nasopharynx. • It may be possible to pass a well-curved tube in a ‘blind’ manner, but more flexible tubes will need assistance if they are to be passed through the vocal cords. • Magill’s intubating forceps are commonly used for this purpose.
- 19. NOSE • Nasal obstructionmay cause gross discomfort; thus, packing the nose after surgery may cause restlessness upon emergence from on anaesthetic. • choanal atresia may cause cyanosis in the newborn.
- 20. NOSE • The naturalexpiratory resistance of the upper airways is in the order of 1–2 cmH2O and can be increased subconsciously to provide a natural form of continuous positive airway pressure (CPAP). • Intubation of the trachea decreases this natural expiratory resistance.
- 21. PHARYNX • Nasopharynx • Oropharynx •Laryngopharynx
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- 23. PHARYNX • NASOPHARYNX: Passageway for air only. • soft palate is elevated during swallowing to block the nasopharynx and prevent food or saliva from going up rather than down. • In the lateral walls of the nasopharynx, paired auditory/eustachian tubes connect the nasopharynx to the middle ear. • Posterior nasopharynx wall also houses a single pharyngeal tonsil (commonly called the adenoids).
- 24. PHARNYX • OROPHARYNX: • Arch-likeentranceway – fauces • From the soft palate to the tip of the epiglottis. • Two types of tonsils in the oropharynx – Palatine tonsils – in the lateral walls of the fauces – Lingual tonsils – covers the posterior surface of the tongue
- 25. PHARNYX • Waldeyer’s ring:The palatine and pharyngeal tonsils, together with lymph collections on the posterior part of the tongue and in relation to the Eustachian orifice. • Form a more or less continuous ring of lymphoid tissue around the pharyngeal entrance,which is termed Waldeyer’s ring.
- 26. WHAT IS LUDWIG’SANGINA ? • Ludwig’s angina :Because of the fascial coat, inflammatory oedema may spread downwards from infections within the mouth or the tonsils or from dental sepsis. • The spread of the oedema is restricted by the pharyngeal fascia and produces swelling and oedema of the tissues of the larynx and pharynx. • This may produce difficulty in swallowing and then rapidly progresses to laryngeal obstruction unless the seriousness of the situation is realized and surgical drainage of the deep pharyngeal tissues performed. • Similar complications can occur after operations involving the floor of the mouth. • The anaesthetist should always consider the advisability of tracheostomy in these patients.
- 27. PHARYNX • The laryngopharynx:from the tip of the epiglottis to the lower border of the cricoid at the level of C6. • Permits passage of both food and air. • Piriform fossa: The larynx bulges back into the centre of the laryngopharynx, leaving a recess on either side. • Here swallowed sharp foreign bodies such as fish bones tend to impact.
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- 29. PIRIFORM FOSSA IMPLICATION •The internal branch of the superior laryngeal nerve passes in the submucosa of the piriform fossa. • Local anaesthetic solutions applied to the surface of the piriform fossa on wool balls held in Krause’s forceps will produce anaesthesia of the larynx above the vocal cords. • This is a useful nerve block to supplement oral anaesthesia for laryngoscopy.
- 30. PHARYNX • Muscles ofthe Pharynx • Superior, Middle, and Inferior constrictor muscles - fibers run in a somewhat circular direction. • Cricopharyngeus muscle- lower part of the inferior constrictor, which arises from the cricoid cartilage. • Stylopharyngeus and Salpingopharyngeus muscles - fibers run in a somewhat longitudinal direction.
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- 33. PHARYNX • Nerve Supply: •All muscle except Stylopharyngeus -Pharyngeal plexus • Stylopharyngeus – Glossopharyngeal nerve • Sensory Nerve Supply of Pharyngeal Mucous Membrane • Nasal pharynx: The maxillary nerve (V2) • Oral pharynx: The glossopharyngeal nerve • Laryngeal pharynx : The internal laryngeal branch of the vagus nerve
- 34. IMPORTANCE OF PHARYNX •Before larynx its pharynx which makes the main airway ; hence necessory part to be managed first. • Helps in deglutition, protects larynx from aspiration.
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- 39. LARYNX • Voice boxis a short, somewhat cylindrical airway ends in the trachea. • Prevents swallowed materials from entering the lower respiratory tract. • Conducts air into the lower respiratory tract. • Produces sounds. • Supported by a framework of nine pieces of cartilage (three individual pieces and three cartilage pairs) that are held in place by ligaments and muscles.
- 40. Larynx • Nine c-ringsof cartilage form the framework of the larynx • thyroid cartilage – (1) Adam’s apple, hyaline, anterior attachment of vocal folds, testosterone increases size after puberty • cricoid cartilage – (1) ring-shaped, hyaline • arytenoid cartilages – (2) hyaline, posterior attachment of vocal folds, hyaline • cuneiform cartilages - (2) hyaline • corniculate cartlages - (2) hyaline epiglottis – (1) elastic cartilage
- 42. SURFACE MARKINGS OFLARYNX
- 43. LARYNX • Muscular wallsaid in voice production and the swallowing reflex • Glottis – the superior opening of the larynx • Epiglottis – prevents food and drink from entering airway when swallowing
- 44. VOCAL CORDS • Inferiorligaments are called the vocal folds. • True vocal cords : produce sound when air passes between them . • Superior ligaments are called the vestibular folds. • False vocal cords : no function in sound production, protect the vocal folds. • The tension, length, and position of the vocal folds determine the quality of the sound.
- 46. LARYNX • Cavity ofthe Larynx • The cavity of the larynx extends from the inlet to the lower border of the cricoid cartilage, where it is continuous with the cavity of the trachea. It is divided into three regions: • The vestibule, which is situated between the inlet and the vestibular folds • The middle region, which is situated between the vestibular folds above and the vocal folds below • The lower region, which is situated between the vocal folds above and the lower border of the cricoid cartilage below
- 47. LARYNX • Sinus ofthe Larynx • The sinus of the larynx is a small recess on each side of the larynx situated between the vestibular and vocal folds. • It is lined with mucous membrane. • Saccule of the Larynx • The saccule of the larynx is a diverticulum of mucous membrane that ascends from the sinus . • The mucous secretion lubricates the vocal cords.
- 48. LARYNX • Muscles ofthe Larynx • Extrinsic Muscles • move the larynx up and down during swallowing. • many of these muscles are attached to the hyoid bone, which is attached to the thyroid cartilage by the thyrohyoid membrane. • movements of the hyoid bone are accompanied by movements of the larynx. • Elevation: The digastric, the stylohyoid, the mylohyoid, the geniohyoid, the stylopharyngeus, the salpingopharyngeus, and the palatopharyngeus muscles • Depression: The sternothyroid, the sternohyoid, and the omohyoid muscles
- 49. LARYNX • Intrinsic Muscles •Two muscles modify the laryngeal inlet: • Narrowing the inlet: The oblique arytenoid muscle • Widening the inlet: The thyroepiglottic muscle • Five muscles move the vocal cords: • Tensing the vocal cords: The cricothyroid muscle • Relaxing the vocal cords: The thyroarytenoid (vocalis) muscle • Adducting the vocal cords: The lateral cricoarytenoid muscle • Abducting the vocal cords: The posterior cricoarytenoid muscle • Approximates the arytenoid cartilages: The transverse arytenoid muscle
- 50. LARYNX • Nerve Supplyof the Larynx • Sensory Nerves • Above the vocal cords: The internal laryngeal branch of the superior laryngeal branch of the vagus. • Below the level of the vocal cords: The recurrent laryngeal nerve. • Motor Nerves • All the intrinsic muscles of the larynx except the cricothyroid muscle are supplied by the recurrent laryngeal nerve. • The cricothyroid muscle is supplied by the external laryngeal branch of the superior laryngeal branch of the vagus.
- 51. LARYNX • Blood Supplyof the Larynx • Upper half of the larynx: The superior laryngeal branch of the superior thyroid artery • Lower half of the larynx: The inferior laryngeal branch of the inferior thyroid artery
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- 59. The position ofthe laryngoscope in the normal patient
- 60. The receding chinand poorly- developed mandible.
- 61. LARYNGOSCOPY GRADING SYSTEM The Cormackand Lehane laryngoscopy grading system. Grade 1: all structures visible. Grade 2: only posterior part of glottis visible. Grade 3: only epiglottis seen. Grade 4: no recognizable structures.
- 62. TRACHEA • A flexibletube also called windpipe. • about 11.25 cm long and 2.5 cm in diameter • Extends through the mediastinum and lies anterior to the esophagus and inferior to the larynx. • Anterior and lateral walls of the trachea supported by 15 to 20 C-shaped tracheal cartilages. • Cartilage rings reinforce and provide rigidity to the tracheal wall to ensure that the trachea remains open at all times • Posterior part of tube lined by trachealis muscle
- 63. TRACHEA • At thelevel 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. • The most inferior tracheal cartilage separates the primary bronchi at their origin and forms an internal ridge called the carina • The upper two thirds--> inferior thyroid arteries • The lower third --->bronchial arteries.
- 65. TRACHEA • Unilateral orbilateral enlargement of the thyroid gland can cause gross displacement or compression of the trachea. • Dilatation of the aortic arch (aneurysm) can compress the trachea. • Inhaled Foreign Bodies--->Right lung.
- 66. BRONCHIAL TREE • Air-conductingpassages that originate from the left and right primary bronchi. • Progressively branch into narrower tubes before terminating in terminal bronchioles. • Incomplete rings of hyaline cartilage support the walls of the primary bronchi to ensure that they remain open. • Right primary bronchus - shorter, wider, and more vertically oriented. • Foreign particles are more likely to lodge in the right primary bronchus.
- 67. BRONCHIAL TREE • Theprimary bronchi ---> hilus of each lung together with the pulmonary vessels, lymphatic vessels, and nerves. • Primary bronchus---> several secondary bronchi . • Left lung has two secondary bronchi. • Right lung has three secondary bronchi. • They further divide into tertiary bronchi. • Each tertiary bronchus is called a segmental bronchus because it supplies a part of the lung called a bronchopulmonary segment.
- 68. PRIMARY BRONCHI Right bronchus Larger –Leaves the trachea at 25o angle – Divides into secondary bronchi before entering the lung – 10 bronchopulmonary segment Left bronchus – Departs the trachea at 45o angle – Does not divide into secondary bronchi until it reaches the lung – 8 bronchopulmonary segment
- 69. LUNGS • Cone shaped •Total volume of 3.5-8.5 liters • Superior portion is apex • Inferior portion is base • Apical portion rises above the clavicle • Attached by hilum and pulmonary ligament
- 70. LUNGS Left Lung • dividedinto 2 lobes by oblique fissure • smaller than the right lung • cardiac notch accommodates the heart Right Lung • divided into 3 lobes by oblique and horizontal fissure • located more superiorly in the body due to liver on right side
- 71. LUNGS • Bronchopulmonary segmentsare as follows: • Right lung • Superior lobe: Apical, posterior, anterior • Middle lobe: Lateral, medial • Inferior lobe: Superior (apical), medial basal, anterior basal, lateral basal, posterior basal • Left lung • Superior lobe: Apical, posterior, anterior, superior lingular, inferior lingular • Inferior lobe: Superior (apical), medial basal, anterior basal, lateral basal, posterior basal
- 73. SURFACE ANATOMY OFLUNGS
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- 76. LUNGS • Pulmonary Circulation –Pulmonary artery • carry blood to the lungs for oxygenated. These vessels are central in each bronchopulmonary segment and branch in a manner similar to the segmental bronchi. They are considered segmental in nature. – Pulmonary vein • at the periphery of each segment and are considered intersegmental. • Bronchial artery(branches of the descending aorta): supply blood to the lungs. One for right lung and two for left lung.
- 77. NERVES TO LUNGS •At the root of each lung is a pulmonary plexus composed of efferent and afferent autonomic nerve fibers. The plexus is formed from branches of the sympathetic trunk and receives parasympathetic fibers from the vagus nerve. • The sympathetic efferent fibers --> bronchodilatation and vasoconstriction. • The parasympathetic efferent fibers--->bronchoconstriction, vasodilatation, and increased glandular secretion.
- 78. VENTILATION OF THELUNGS • Young children-->ribs are nearly horizontal--->Rely mainly on the descent of the diaphragm to increase their thoracic capacity on inspiration--->Referred to as the abdominal type of respiration. • After the second year of life, the ribs become more oblique, and the adult form of respiration is established. • In the adult a sexual difference exists . • The female tends to rely mainly on the movements of the ribs rather than on the descent of the diaphragm on inspiration. This is referred to as the thoracic type of respiration. • The male uses both the thoracic and abdominal forms of respiration, but mainly the abdominal form.
- 79. MUSCLE ASSISTING VENTILATION •The scalenes help increase thoracic cavity dimensions by elevating the first and second ribs during forced inhalation. • The ribs elevate upon contraction of the external intercostals, thereby increasing the transverse dimensions of the thoracic cavity during inhalation. • Contraction of the internal intercostals depresses the ribs, but this only occurs during forced exhalation. • Normal exhalation requires no active muscular effort.
- 81. INHALATION AND EXHALATION Figure15–6. Actions of the respiratorymuscles. (A)Inhalation:diaphragm contracts downward;external intercostalmuscles pull ribcage upward and outward; lungs are expanded. (B) Normal exhalation :diaphragm relaxes upward;rib cage falls down and in as external intercostal muscles relax; lungsare compressed.
- 82. PLEURA • The outersurface of each lung and the adjacent internal thoracic wall are lined by a serous membrane called pleura. • The outer surface of each lung is tightly covered by the visceral pleura. • while the internal thoracic walls, the lateral surfaces of the mediastinum, and the superior surface of the diaphragm are lined by the parietal pleura. • The parietal and visceral pleural layers are continuous at the hilus of each lung
- 83. PLEURAL CAVITY The potentialspace between the serous membrane layers is a pleural cavity. • The pleural membranes produce a thin, serous pleural fluid that circulates in the pleural cavity and acts as a lubricant, ensuring minimal friction during breathing. • Pleural effusion – pleuritis with too much fluid
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