Clinical Anatomy of the European Hamster 
elastic cartilages that are almost triangular in shape 
(Fig. 3-18). They lie between the thyroid laminae, 
and their caudal ends articulate with the cranio- 
dorsal cricoid laminae. A muscular process {proc- 
essus muscularis) is bent laterally, while a vocal 
process (processus vocalis) points ventrally and 
possesses a small hook at its cranial edge. 
The epiglottis is a leaf like structure that protects 
the entrance to the glottis (Fig. 3-18). The cranio- 
ventral surface of the epiglottis lies adjacent to the 
free, caudal edge of the soft palate, and the tip 
{apex) projects dorsally into the pharynx. Ventral 
to this free edge, the epiglottis closes the pharynx 
caudally. The craniodorsal edge of the epiglottis 
forms an arch which bends laterally and continues 
medially, narrowing to form the base {basis). The 
epiglottis is composed of elastic cartilage. 
At the dorsal part of its inner surface, the epiglottis is covered by 
stratified squamous epithelium, while the remaining inner surface is 
of a pseudostratified ciliated columnar epithelium. At the cranial base 
of the epiglottis, the uniform structure of this epithelium is interrupted 
by excretory ducts of some subepithelial glands so that the epithelium 
sometimes takes on a mixed appearance (Fig. 3-18). 
The dorsal part of the lateral walls of the vestibule of the larynx is 
covered with stratified squamous epithelium, whereas its ventral sur- 
face is coated with pseudostratified ciliated columnar epithelium. At 
the vestibular fold (plica vestibularis) this stratified columnar epi- 
thelium is also found, while the vocal folds {plicae vocales) are coated 
with stratified squamous epithelium. Between these two folds is situa- 
ted the ventricle of the larynx, which is lined by a pseudostratified 
ciliated cylindrical epithelium with areas of stratified squamous epi- 
thelium. Caudally from the vocal folds begins a ciliated columnar 
epithelium, two-cell-layers thick, which extends to the trachea (Fig. 
3-19). 
3.5.1 Ligaments of the Larynx 
The various cartilages of the larynx are connected with each other by 
ligaments. For example, the cricothyroid ligament (lig. cricothyreoi- 
deum) and the thyroepiglottic ligament (Itg. thyreopiglotticum) are 
distinctly visible microscopically. A cricotracheal ligament {lig. crico- 
tracheale) is likewise recognizable. In horizontal section through the 
larynx, the vocal ligament {lig. vacate) is especially prominent histo- 
logically. 
3.5.2 Muscles of the Larynx 
Except for m. arytaenoideus transversus and the 
m. hyoepiglotticus, all muscles of the larynx are 
paired. M. thyreohyoideus joins the hyoid bone to 
the thyroid cartilage. M. sternothyreoideus is prom- 
inent, originating with m. sternohyoideus on the 
manubrium and extending craniodorsally to insert 
on the lateral surface of the thyroid lamina. 
M. cricothyreoideus originates on the cricoid arch 
and runs craniodorsally to the caudal thyroid lam- 
ina. M. cricoarytaenoideus dorsalis originates dor- 
sally on the cricoid lamina and inserts laterally on 
the muscular process of the arytenoid cartilage. M. 
arytaenoideus transversus forms a muscular con- 
nection between the dorsal edges of the two aryten- 
oid cartilages. M. cncotrachealis runs from the 
cricoid arch to the first and second tracheal rings 
dorsally. The minute m. cricoarytaenoideus later- 
alis extends craniodorsally from the cricoid to the 
vocal process of the arytenoid cartilage. M. thyreo- 
arytaenoideus runs ventrally from the vocal process 
of the arytenoid cartilage. The prominent m. vocalis 
parallels m. thyreoarytaenoideus. 
The interior of the larynx is divided into the ves- 
tibule {vestibulum laryngis), the glottis and the 
infraglottis {cavum infraglotttcum). The vestibule 
extends from the laryngeal opening {aditus laryn- 
gis) to the vestibular folds {plicae vestibulares). The 
laryngeal opening is bordered ventrally by the epi- 
glottis, laterally by the aryepiglottic folds {plicae 
aryepiglotticae) and dorsally by the arytenoid carti- 
lages. A plica lateralis is not found. A median ven- 
tricle {ventriculus laryngis medianus) is formed at 
the base of the epiglottis; this is more pronounced 
in older animals. The vestibular fold at the cau- 
dal end of the vestibule is formed by m. ventricu- 
laris and its mucosa. It extends obliquely ventrally 
from the vocal process of the arytenoid cartilage to 
the base of the epiglottis. 
Between the vestibular fold and the vocal fold 
{plica vocalis), a perpendicular fissure is located, 
the lateral ventricle {ventriculus laryngis lateralis), 
which begins cranial to the vocal process of the 
arytenoid cartilage and extends ventrally to lie be- 
tween the m. vocalis and the m. ventricularis. The 
glottis is a laterally compressed space between the 
vocal folds cranially and the infraglottis caudally. 
Hie vocal folds are folded into the rima glottidis, 
especially by the vocal ligament {lig. vocale), a con- 
nective tissue extension of the vocal process of the 
arytenoid cartilage, which extends ventrally, lying 
lateral to m. vocalis. Caudally, the interior of the 
larynx broadens to form the infraglottis, which 
assumes the inner diameter of the first tracheal 
ring, with which it is continuous caudally. 
3.6 TRACHEA 
The cervical and thoracic trachea is a nearly 
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