Fig. 3.1
Set of surgical instruments
Step 1 Skin Landmark Identification
Recognizing the main landmarks on the skin (Fig. 3.2) is probably the most simple and fundamental step in all surgical head and neck procedures. Identification by palpation of laryngeal framework in sheep animal model is quite similar to human. Before starting the procedure, it is useful to identify:
Fig. 3.2
Superficial landmark identification. HB hyoid bone, partial cover by the muscles, ThC thyroid cartilage, Cr cricoid cartilage, Tr trachea
Step 2 Superficial Layer Dissection
Make a horizontal incision about 3–4 cm in order to show the superficial fascia that covers the muscles of the neck (Fig. 3.3). Incision could be performed with 10 or 15 blade.
Fig. 3.3
Skin incision; superficial cervical fascia dissected. Below structures that are covered by its fascia
In this step the main goal is to elevate only a cutaneous and subcutaneous flap.
When all superficial fascia is exposed, the surgeon has to dissect it on the midline with surgical scissor or blade (Fig. 3.3).
Step 3 Laryngeal and Tracheal Framework Identification
When the dissection of the superficial layers is completed, it is important to identify the main structures of laryngeal and tracheal framework and muscles surrounding the larynx (Fig. 3.4).
Fig. 3.4
Larynx exposed with muscles surrounding it
Step 4 Infrahyoid Muscle Dissection
This step simulates the strap muscle dissection on the midline performed in the human procedure in order to expose the trachea. Sheep thyroid does not have an isthmus so it is not necessary to split thyroid gland on the midline (Fig. 3.5).
Fig. 3.5
(a) Strap muscle dissection. (b) Tracheal explosion
Step 5 Incision of the Trachea
The debate is still ongoing as to whether a vertical or horizontal tracheal incision, with or without flap, should be made. The basic principle consists of incising as few tracheal rings as possible (Figs. 3.6 and 3.7).
