Page 112 - BSAVA Manual of Canine and Feline Head, Neck and Thoracic Surgery, 2nd Edition

Chapter 8
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Surgery of the extrathoracic

trachea

Zoë J. Halfacree and Chick Weisse

Anatomy and physiology

The trachea extends from the cricoid cartilage of the
larynx to the carina at the level of the heart base, where it
divides to form the mainstem bronchi. It is composed of
between 35 and 46 incomplete C-shaped cartilage rings
that are united dorsally by the dorsal tracheal ligament
and trachealis muscle and joined together by fibroelastic
tissue, the annular ligaments, to form a circular tube in
cross section (Figure 8.1). The trachea is lined by mucosa
composed of a pseudostratified columnar epithelium,
which contains ciliated epithelium and goblet cells. The
cervical trachea has a delicate segmental blood supply, The segmental blood supply to the trachea is derived from the
which arises as branches from the cranial and caudal 8.2 cranial and caudal thyroid arteries.
thyroid arteries (Figure 8.2); venous drainage is via
the internal jugular veins. The trachea is innervated by the
vagus and recurrent laryngeal nerves.
The trachea serves as a conduit for passage of air to Indications for surgery of the
and from the lungs during ventilation, but also plays a role
in warming and filtering the air following inhalation. The extrathoracic trachea
mucociliary escalator, provided by the ciliated epithelium,
plays an essential role in clearing particulate matter from • Tracheal trauma:
the lungs. • Perforation or avulsion of the trachea
• Tracheal necrosis, e.g. secondary to endotracheal
intubation injury.
• Management of segmental tracheal stenosis.
• Management of obstructive tracheal masses (mural or
intramural).
• Management of tracheal collapse.
• Management of upper airway obstruction by temporary
Tracheal
Adventitia mucosa and or permanent tracheostomy.
submucosa

Tracheal trauma

Tracheal trauma may be caused by external or internal
forces. External forces include bite wounds, cervical stick
injury and choke chain injuries. Internal trauma to the
trachea may be caused iatrogenically following inappro-
priate use of an endotracheal tube.
Owing to the complex nature of the forces exerted from
a bite wound to the neck (penetrating, avulsion and crush-
Cartilage Trachealis ing forces), a range of different injuries may be observed.
muscle Penetrating injuries may cause perforation of the trachea
and the development of a ‘sucking’ cervical wound and
extensive subcutaneous emphysema. Even in the absence
of a full-thickness skin wound, tracheal avulsion or crico-
8.1 Cross-sectional anatomy of the trachea.
tracheal separation may occur, resulting in the development

BSAVA Manual of Canine and Feline Head, Neck and Thoracic Surgery, second edition. Edited by Daniel J. Brockman, David E. Holt and Gert ter Haar. ©BSAVA 2018 103

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