7 CARTILAGES OF THE LARYNX. 909 
the hyoid bone by the lateral thyro-hyoid ligament. he inferior cornu is shorter 
and stouter than the superior cornu. As it proceeds downwards it curves slightly 
inwards, and upon the inner face of Hyoid bone —_Epiglottis 
its extremity it shows a circular flat aS LS, 
facet, by means of which it articulates | 
with a similar facet on the lateral 
aspect of the cricoid cartilage. The / 
superior border of the ala is for the i lanes ya 
most part sheghtly convex, and in miemDrae ay 
front it dips suddenly down to become Superior comn of —- 
continuous with the margin of the i 
thyroid notch. Posteriorly, where it 
joins the superior cornu, it exhibits Thyroid mee 
Cartilago triticea 
a shallow notch or concavity. The 
inferior border is to all intents and Pomun eee 
\e 
purposes horizontal, but it is marked Guiéa-thewoid 
off by a projection, termed the inferior membrane 
tubercle, into a short posterior part, Inferior cornu of 
sn . aie ; ae os s thyroid cartilage 
which shows a shallow concavity in 
front of the inferior cornu, and a_ Cricoid eartilage 
longer part which hes in front of the Tag 
¥ COCA 
tubercle, which is also concave, but to i, 5 
a less degree. The external surface ay ayant 
of the ala is divided into two unequal Witteman walla Wy 
areas by an oblique line or ridge. ts = a 
his Ji hea ieee aie a Fira, 612.—THE CARTILAGES AND LIGAMENTS OF THE 
us line begins above at the superior LARYNX VIEWED FROM THE FRONT. 
tubercle, a prominence situated im- 
mediately below the superior border, and a short distance in front of the root of 
the superior cornu. From this the oblique line proceeds downwards and _ forwards, 
to end inferiorly in the inferior tubercle on the lower border of the ala. The area 
which lies behind the oblique line is much smaller than that which les in front. 
It is covered by the inferior constrictor muscle 
(> Epiglottis of the pharynx. The larger anterior area is for 
x the most part covered by the thyro-hyoid 
Hyoid bone Musele. To the oblique line are attached the 
cartilacy  8Uerno-thyroid and thyro-hyoid muscles. The 
triticea inner surface of the ala of the thyroid cartilage 
Thyro-hyoid 
“menbrane. 18 Smooth and slightly concave 
os Swanson Cricoid Cartilage (cartilago ericoidea).— 
fan Lhe, cricoid cartilage is shaped lke a signet- 
ring. Behind, there isa broad, thick, and some- 
Superior 
_ tubercleon what quadrilateral plate, termed the posterior 
ala o Z - 5 A 
thyroid lamina; whilst in front and laterally, the cir- 
cartilage 
cumference of the ring is completed by a curved 
’ (ben line Hand, called the anterior arch. The lumen of 
ee tubercle the ring enclosed by these parts is circular 
Inferior cornu of 17 S =o aene Se pee ra b= 3 
thyroid cartilage below, but above, the ring is compressed later- 
Crico-thyroid aly, so that the lumen becomes elliptical. The 
membrane : ° ° 
Cricoid cartilage SUperior border of the posterior lamina presents 
a faintly-marked mesial notch. On either side 
of this there is an oval convex facet which 
looks more outwards than upwards, and which 
articulates with the base of the arytenoid 
cartilage. The posterior surface of the lamina 
is divided by an elevated median ridge into two 
depressed areas which give attachment to the 
posterior crico-arytenoid muscles. The front part of the anterior arch of the cricoid 
is in the form of a narrow band, but as it proceeds backw ards towards the posterior 
lamina its superior border rises rapidly, and in consequence the arch becomes much 
Fic. 613.—PROFILE VIEW OF 3 CARTILAGES 
AND LIGAMENTS OF THE Gare NX. 
