Chapter 102 Trachea and Bronchi Flashcards
Label the diagram


How many terminal bronchioles are dogs estimated to have?
17,000 - 36,000
What type of cartilage are tracheal rings composed of?
Tracheal rings composed of hyaline cartilage
What is the name of dorsal muscle connecting traceal rings (N.B. inserts to external surface of tracheal rings)
Trachealis muscle

Approximately how many tracheal rings are there (and upper range)
Approx 35 tracheal rings (up to 46 reported)
What si the name of the tissue between tracheal rings?
Annular ligament
How many cartilage rings is the left mainstem bronchus typically made up of? And the right?
Typically 3 rings in left mainstem bronchus, only 1 in right.
How are bronchioles distinguised from smaller bronchi?
Smaller bronchi contain overlapping cartilage plates (rather than rings); diasppearance of plates marks transition to bronchiole.
List the layers of the trachea:
- Mucosa
- Submucosa
- Fibrocartilaginous layer
- Adventitia (in cervical trachea), serosa (in thoracic trachea).
where along thelength of the trachea is the cartilage the thinnest and the luminal diameter smallest?
At thoracic inlet
What type of epithelium lines the trachea?
Ciliated, pseudostratified, columnar epithelium
Aside from goblet cells, there are other mucus secreting glands in the trachea.
- What are they named?
- How do they differ from goblet cells?
- What is the pproximate density of these cells in canine trachea?
- What are they named? Tubuloalveolar mucus glands
- How do they differ from goblet cells? Produce equivalent mucous of 40 goblet cells
- What is the pproximate density of these cells in canine trachea? 1 opening/mm
During progression down the bronchial tree, how does ‘cell population’ vary?
Tubuloalveolar glands disappear first, then goblet cells, then ciliated cells.
Where does the trachea receive its segmental blood supply from?
Cranial and caudal thyroid arteries. Branches travel towards midline where they extensively anastomose
Where do the mainstem bronchi/bronchioles receive blood supply from?
Broncho-oesophageal arteries.
What is the venous drainage of the trachea/bronchi?
Thyroid vein, jugular vein, broncho-oesophageal veins
List 4 lymph nodes that drain trachea/bronchi:
- Cranial mediastinal
- Medial retropharyngeal
- Deep cervical
- Tracheobronchial
Which nerves supply the trachea/bronchi?
Is there a dominant side (in dogs at least)?
Vagus/recurrent laryngeal
Right dominant side. (L stimulation –> only 28% response compared with R stimulation)
List 3 functions of trachea
- Conduit fo rair passage
- Warms and humidifies air
- Mucociliary clearance
What is the typical mucociliary clearance rate in dogs?
1 - 1.5 cm/min
List two physiological changes that occur with trachealis m contraction
- Increased airflow velocity
- Increased rigidity
- Creates mucosal inversion ‘furrow’ along which mucus collected and expelled
What is the normal ratio of tracheal:thoracic inlet diameter in:
Normal dogs:
Brachy dogs:
English Bulldogs:
Normal dogs: 0.2
Brachy dogs: 0.16
English Bulldogs: 0.13
List 3 radiographic findings of URT obstruction.
And 3 of lower RT obstruction
URT obstruction:
- Tracheal narrowing distal to obstruction
- Tall, domed diaphragm
- Under-aerated lungs
- (Poss pulmonary oedema)
Lower RT obstruction:
- Flattened diaphragm
- Over-inflated lungs
- –> prominent pulmonary vasculature
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What is the advantage of fluoro over rads for evaluatio of trachea?
What is the advantage of CT over rads?
List an advantage of tracheobronchoscopy:
- Fluoro allows dynamic assessment (increased intrathoracic pressure (e.g. during cough) can exacerbate collapse)
- CT results in less under-estimation of dimensions (CT validated as method for diagnosing tracheal hypoplasia, collapse, stenosis in non-anaesthetised dogs and cats = “virtual endoscopy”!)
- Tracheobronchoscopy allows grading of collapse and evaluation of bronchial tree (?presence of bronchomalacia), collection of BAL.



