Page 152 - Manual of Equine Field Surgery

148 HEAD AND NECK SURGERIES

Lingual process of_

basihyoid bone

Pai red ~:::::....! ~~1-4
thyrohyoideus mm.

Cricothyroid --!~+.;.
membrane

Cricoid cartilage -+- g.ib,=~;:.,'
Linguof acial v. -+-~~·

Parotid gland

Paired

sternothyroideus mm.
Paired omohyoideus mm.

Paired sternohyoideus mm. -+-it-':'

Paired sternomandibularis mm. ~e:= ~~

-f;.~,Ulf, .. ~-1:~

Figure 25-1 Ventral view of the head and rostral Figure 25-2 Ventral view of the larynx.

neck with the skin and cutaneous colli muscle removed.

sternothyrohyoideus muscles. The paired ster- long incision is made through the anesthetized

nothyrohyoideus muscles originate from manu- skin on the ventral midline of the neck (Figure

brium sterni and extend on the ventral aspect of 25-3). The level of the caudal portion of the inci-

the trachea. The smaller sternothyroideus inserts sion is at the level where the sternomandibularis

on the caudal border and abaxial surface of the diverges from midline, exposing the paired ster-

thyroid cartilage. The larger sternohyoideus nothyrohyoideus muscles. The rostral portion of

muscle inserts on the basihyoid bone and the the incision is at the level of convergence of the

lingual process of the hyoid bone (Figures 25-1 omohyoideus and sternohyoideus muscles. At this

and 25-2). The paired omohyoideus muscles orig- mid-cervical region, the sternothyrohyoideus

inate from the subscapular fascia close to the muscles are well exposed and are relatively free

shoulder joint and merge with the sternohyoideus from other structures.

in the proximal third of the neck. The incision is continued through the subcu-

Important landmarks for the laryngotomy taneous tissue and the cutaneous colli muscle. The

incision include the paired sternohyoideus sternohyoideus muscle is then exposed and split

muscles overlying the larynx and the V-shaped longitudinally on midline. The dissection contin-

cricothyroid membrane, which lies between the ues laterally along the trachea to the lateral

thyroid and cricoid cartilages. borders of the sternothyrohyoideus muscles. The

ventral surface of the muscles is then separated

from the cutaneous colli and sternomandibularis

PROCEDURE muscles by scissors and blunt finger dissection.

The dissection should continue until a 5-cm lon-

Myectomy and Tenectomy Procedures gitudinal section of the paired muscle is under-

mined and separated from the surrounding

Sternothyrohyoideus Myectomy tissues. The combined sternothyrohyoideus mus-

This procedure can be performed in the standing cles are elevated from the wound and an approx-

patient or under general anesthesia, A 6- to 8-cm- imately 5-cn1 length of muscle is removed by