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Questions and Answers
What is the primary muscle responsible for normal tidal volume respiration?
Which of the following statements about the diaphragm is true?
What is the normal range of diaphragm movement during deep breathing?
Which of the following factors can affect the position of the diaphragm?
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What is the primary function of the external intercostal muscles?
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What is the primary function of the internal intercostal muscles?
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Which of the following is an inwardly directed force in the alveoli that must be overcome during inspiration?
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What is the term used to describe the ease with which the lungs and thoracic wall can be expanded?
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Which of the following is responsible for decreasing the size of the alveoli during expiration?
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Which law relates the pressure and volume of a gas?
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Which of the following is the least common anatomical variation of the ribs?
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What is the significance of the sternal angle (of Louis) in relation to the trachea?
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Which of the following is the primary function of the nasal conchae and paranasal sinuses?
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What is the significance of the trachea being posterior to and in line with the jugular notch?
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What is the primary function of the ala nasi, the flared portion of the lateral wall of each nostril?
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What is the primary function of the arytenoid cartilages in the larynx?
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What is the significance of the cricoid cartilage in the pediatric airway?
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Which of the following statements about the anatomical differences between the adult and pediatric larynx is true?
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What is the primary function of the corniculate cartilages in the larynx?
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What is the significance of the rima glottidis in the larynx?
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Which of the following statements about the trachea is correct?
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What is the primary function of the carina?
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Which of the following statements about the bronchial circulation is correct?
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Which of the following structures is responsible for the turbulent flow that helps trap inhaled particles in the respiratory system?
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Which of the following statements about the innervation of the larynx is correct?
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Which of the following is a characteristic of the human sternum?
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What is the purpose of the sternal angle (angle of Louis) on the human sternum?
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Which of the following is a true statement about the human trachea?
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What is the primary function of the nose in the human upper airway?
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What is the anatomical term used to describe the presence of extra ribs arising from the lumbar vertebrae?
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Study Notes
Larynx
- Located in adults between C3-C6, and C3-C5 in children
- Framework formed by 9 total pieces of cartilage (3 paired, 3 unpaired)
- Epiglottic cartilage: most superior
- Thyroid cartilage: largest, forms laryngeal prominence at C5
- Cricoid cartilage: connects larynx to trachea
- Arytenoid cartilages (2): posterior to thyroid cartilage
- Corniculate cartilages (2): attached to arytenoid cartilages
- Cuneiform cartilages (2): support soft tissue between arytenoids and epiglottis
Laryngeal Cavity
- Rima glottidis: opening between true vocal cords and arytenoid cartilages
- Narrowest portion of the airway
- Glottis: true vocal cords and the rima glottidis
Pediatric Airway Differences
- In pediatric patients, cricoid was considered the narrowest portion of the airway
- Newer studies suggest the glottic opening may be the narrowest in pediatric patients
- Shapes and locations of structures also vary between infant and adult
Intubation
- Easy to insert laryngoscope blade too deep in children
- Must be careful not to hide the larynx
Larynx Innervation
- Innervation of the larynx: CN X (Vagus)
- Sensory: Interior Branch of Superior laryngeal nerve provides sensation for upper portion of the larynx down to and including upper half of the vocal cords
- Recurrent laryngeal nerve transmits sensation below the true cords and lower half of the cords
- Motor: ALL intrinsic muscles except the cricothyroid are innervated by the RECURRENT LARYNGEAL nerve
- Cricothyroid muscle is innervated by superior laryngeal nerve
Trachea
- Fibrocartilaginous tube, approximately 10-20cm long and 12mm in diameter
- Begins at the end of the larynx (C6) and extends to T5-6
- Supported by 16-20 C-shaped rings of cartilage with smooth muscle posteriorly
- The carina is the lowermost portion of the trachea where it divides into primary bronchi
- Lined with ciliated pseudostratified epithelium which functions as mucociliary escalator
Removing Inhaled Particles
- The lungs produce 100mL of mucous per day
- Turbulent flow helps trap precipitate
- Cough Reflex: mucociliary escalator mechanism
- Impaired by endotracheal intubation and volatile anesthetics
- Ciliated epithelial cells beat particles up the airway to be swallowed in the oropharynx
Branching of Tracheobronchial Tree
- Conducting Zone: no gas exchange
- Respiratory Zone: gas exchange occurs
- Dead Space: area where no gas exchange occurs
- Secondary (Lobar) Bronchi: three on the right, two on the left
- Segmental Bronchi: ten on the right, eight on the left
- Terminal Bronchioles: diameter of 1 mm, contains no cartilage
- Relatively thick smooth muscle wall compared to lumen
- Can contract during asthma attack
- No goblet cells
Bronchial Circulation
- Supplied by systemic circulation
- Some mixes with alveolar venous return, causing an anatomic shunt
- AV shunt causes slight dilution of PO2 (bronchial venous mixes with pulmonary vein blood)### Alveolar-Arterial Gradient
- PA - Pa ~ 5-15mmHg, useful in determining the cause of restrictive lung disease
- Normal gradient: blame the chest wall (extrinsic restrictive disease)
- Increased gradient: problem is in the lung (intrinsic restrictive lung disease)
Bronchial Innervation
- Sensory and motor innervation via vagus
- Parasympathetic: Acetylcholine (Ach) causes bronchoconstriction via M3 (Gq) receptors
- Sympathetic: Epinephrine/Norepinephrine causes bronchodilation via B2 (Gs) receptors
Respiratory Zone
- Composed of: acinus (terminal respiratory unit), respiratory bronchioles, alveolar ducts, and alveoli
- Alveoli form from birth to age 4 and continue to maximize expansion until age 8
- Respiratory bronchioles: first segment of airway where gas exchange occurs (transitional zone)
- Alveolar ducts: walls completely lined with alveoli
- Alveolar sac: located at end of each 3rd generation of alveolar ducts
Gas Exchange
- Diffusion: main mechanism for gas exchange from alveoli into blood
- More lipid-soluble anesthetics diffuse easier, resulting in build-up in bloodstream
- Diffusion = Area/Thickness
- Normal lung: area of blood-gas interface is about the size of a tennis court
Alveoli
- 300 million in adult lungs, polygon shape maximizes surface area
- Surrounded by 1,000 pulmonary capillaries each
- Type I alveolar cells: squamous, form walls, involved with gas exchange
- Type II alveolar cells: cuboidal, produce surfactant
- Alveolar macrophages: eliminate foreign debris
- Alveolar pores (pores of Kohn): allow for collateral ventilation
Alveolar Stability
- Alveoli have tendency to collapse, prevented by: surfactant, alveolar pores, and interdependence
Lungs
- Cone-shaped structures located in thorax, occupying all of thoracic cavity except mediastinum
- Right lung has three lobes, left lung has two lobes, and is more narrow
- Lungs innervated by pulmonary plexus, sympathetic fibers (T2-T6), and parasympathetic fibers from vagus
- Few to no pain receptors in lungs
Lungs Perfusion and Ventilation
- Normal perfusion and ventilation (V/Q) difference between the two lungs due to different surface areas
- Right lung has three lobes and receives 60% of cardiac output to lungs
- Parasympathetic fibers produce constriction of airways and increase mucus secretion by mucus glands
- Sympathetic hormones produce dilation of airways (beta-2 response)
Pleural Membranes
- Serous membranes that line thoracic cavity and cover lungs
- 10cc of pleural fluid produced per lung, prevents friction in pleural cavity
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Description
Test your knowledge of the anatomy of the larynx, including cartilages like thyroid, cricoid, and arytenoid. Learn about the position of the larynx in adults and children, as well as the framework formed by different cartilages.
