NORMAL ANATOMY OF THE LARYNX. 
number,* of which three are single and un- 
‘symmetrical, the epiglottis, thyroid, and cri- 
goid ; two are placed laterally, and form a pair, 
ed the arytenoids. Upon the summits 
these are found two minute cartilaginous 
bodies, termed cornicula; the remaining 
0 (which, however, are not always present) 
fe situated anterior to the arytenoids, and in- 
volved in the aryteno-epiglottic folds, named 
_ the cuneiform cartilages. 
The cricoid cartilage. Gr. xeiKog, a ring, 
#100 3 Lat. Cartilago annuliformis ; Fr. Cri- 
edide ou annulaire ; Germ. Ringknorpel ; Ltal. 
ricoide.—This cartilage, situated at the base 
of the larynx, which it supports, is the thickest 
_ stron 
st of the whole assemblage of car- 
t is connected to the first ring of the 
a by elastic ligaments and mucous memn- 
its form, that of a ring, is not quite 
 Gireular, but approaching to an elliptical figure. 
t is shallow in front, at c, e, (fig. 20,) but it 
thicker and deeper than the first ring of the 
_ trachea; and, posteriorly, it is considerably 
_ deeper than at its anterior part, in the propor- 
ion of eight to two and a-half. 
Fig. 20. 
A, an anterior, B, the side view of the cricoid 
) Cartilage; a, the posterior superior margin; 5, b, 
‘the crico-arytenoid articulating surface; 6, 9, f, e, 
the superior descending margin ; d, e, the tracheal 
ure of the cricoid ; a, d, the greatest, a, c, the 
‘ depth of surface; a, e, the obliquity of the 
‘superior section to the axis; A, the left surface 
‘articulating with the inferior cornua of the thyroid 
| cartilage. 
_ The anterior external surface gives attach- 
ment to the crico-thyroid muscles (see fig. 26); 
more posteriorly we find an apophysis for the 
iculation of the thyroid (fh, fig. 20, B). Its 
osterior surface is divided into two equal por- 
tions by a vertical ridge along its middle line, 
a, d, fig. 20, B. This ridge, which was first 
noticed by Galen, gives attachment to some 
longitudinal fibres of the esophagus. On each 
side of it a concave surface is observed, which 
Bives origin to the crico-arytenoidei postici, 
9 €y fig 27. 
cee internal surface is smooth, and lined by 
the mucous membrane of the larynx. The 
| inferior margin is horizontal, and nearly circu- 
| 
: 
af 
- Galen describes only three, yov3pog bupecesdns, 
KovBpoc Dewrepos, xovdpos a-uTasvoesdnc. 
101 
lar; but the superior, which is bevelled 
obliquely inwards and upwards, about ec, e, 
(fig. 20,) ascends backwards in the direction 
of e, fig, 6, (fig. 20,) being slightly curved 
downwards between f° and g. The anterior 
superior outline of this cartilage presents that 
of the section of a cylinder, whose obliquity to 
its axis is in the direction a, e, and therefore is 
elliptical. It recedes anteriorly from the lower 
margin of the thyroid cartilage in the direction 
of g, f; e, (fig. 20,) leaving an interval called 
the crico-thyroid space, a, (fig. 20, B,) which is 
occupied by the crico-thyroid ligament ; on each 
side, in the lines e, f, g, by the lateral liga- 
ments, and more posteriorly by the crico- 
arytenoidei lateralgs, in the space f, g, to the 
external side of 6 (fig. 20). 
The posterior superior margin is horizontal 
on each side of a, (fig. 20,) and parallel to the 
inferior at d, having at 6 and 6 an oblong, 
oblique, and slightly cylindrical surface, in- 
clined upwards and outwards for the articu- 
lation of the arytenoid cartilages. These sur- 
faces are considered by Willis as “ portions of 
cylinders, whose axes are inclined both with 
respect to the horizontal and vertical sections.” 
In the vertical section, the projection of this 
articulating axis is in the position G, C, (fig. 
28,) and in the horizontal, in the line O, P, 
(fig. 30.) Between these surfaces is a slight 
depre:sion for the insertion of the arytenoid 
muscles. 
The thyroid cartilage. Syn. Lat. Cartilago 
scutiformis ; Fr. Thyroide ; Germ. Schildknor- 
pel.—This cartilage derives its name from Queeos, 
a shield, and edocs, form. It embraces the 
cricoid in a manner analogous to the carapax 
of the tortoise. It is formed to protect the 
internal mechanism of the larynx, both in front 
and at both sides, but is open behind. It serves 
Fig. 21. 
An angular view of the thyroid cartilage. a, the 
notch ; 6, b, the superior cornua ; c,c, the inferior 
cornua ; g, g, the superior tubercles ; h, h, the in- 
ferior tubercles; e, e, the wings of the thyroid ; 
i,a,i, the superior margin; h, d, h, the inferior 
margin ; a, d, the mesial line; f, the pomum. 
as a fulcrum and lever for the action of several 
muscles. It is composed of two quadrilateral 
lamine uniting in front at the mesial line (a, d, 
