946 
membrane is of great width at its origin, the 
external carotid foramina marking off the la- 
teral limits, but it quickly narrows as it de- 
scends: the sharp angle which it forms is 
brought into relation with the internal carotid 
artery and superior cervical ganglia of the sym- 
pathetic nerve: in the interior of the pharynx 
a longitudinal sulcus, sometimes crossed by a 
transverse slip, will be found behind the open- 
ing of the Eustachan tube, leading to a cul-de- 
sac which occupies this angle. 
The pharynx is surrounded by muscular 
fibres which have been collected into three 
distinct muscles on either side, and named, 
from their action, constrictors; these may be 
considered as intrinsic: two other muscles on 
either side are inserted into its walls, and are 
extrinsic as not belonging so exclusively to it. 
The constrictor muscles are membraniform, 
Spreading as thin muscular lamine around the 
sides and back part of the pharynx, and have 
@ common insertion into a posterior median 
raphé: they partly overlap each other from 
below upwards, so that the inferior constrictors 
alone can be wholly examined without inter- 
fering with the rest, and are invested on their 
outer surface with a dense fascia: they arise by 
numerous and distinct points of attachment, 
which gave occasion to their being divided 
originally into several muscles, each with its 
appropriate name given according to its par- 
ticular origin: these are now reduced to three 
on each side, and arranged into superior, middle, 
and inferior. 
Constrictor pharyngis inferior.* — This 
muscle is the thickest and strongest of the set, 
has an irregular quadrilateral outline, and is 
situated at the lower part of the pharynx: it 
derives its origin from the cricoid and thyroid 
cartilages by two slips: the one, triangular and 
fleshy, arises from the side of the cricoid car- 
tilage between the origins of the crico-arytenoi- 
deus posticus and crico-thyroideus muscles : 
from the latter it occasionally receives a few 
fibres: the other, broader and more extensive, 
lies on the ala of the thyroid cartilage, and 
arises from the two tubercles, which the ala 
presents on its external surface, and from a 
tendinous structure that stretches obliquely 
from one tubercle to the other: it is here 
blended with the attachments of the sterno- 
thyroid and thyro-hyoid muscles: it also em- 
braces the inferior cornu of the thyroid carti- 
lage: from these f sears it spreads round the 
side and back of the pharynx to the posterior 
median raphé, into which it is inserted con- 
jointly with the muscle from the opposite side; 
the fibres pass in different directions: the su- 
perior are longer and pursue a more oblique 
course upwards, while the nearer they are ex- 
amined to the lower margin of the muscle, the 
shorter and less oblique they become, and at 
length assume nearly a transverse direction. 
The origins of the inferior constrictor muscle 
are concealed by the thyroid gland and sterno- 
thyroid muscle : it is in relation laterally to the 
* Thyro-pharyngeus, crico-pharyngeus. 
PHARYNX. 
sheath of the carotid vessels, and posteriorly to 
the cervical vertebra and deep muscles of the 
neck: its internal surface is applied partly 
upon the mucous membrane and the terminal 
fibres of the syle phacnges and palato-pha- 
ryngeus muscles, but to a greater extent upon 
the middle constrictor muscle: the obli 
upper margin extends as high as the middle of 
the pharynx and close by its thyroid attach- 
ment allows the superior laryngeal nerve to 
pass beneath it: the circular fibres of the ceso- 
Ee are connate. its nes i 
ut distinguishe their greater delicacy 
paler colour: ania Na the cricoid cartilage the 
inferior or recurrent laryngeal nerve slips be- 
neath its lower margin. Some of the lower 
fibres have occasionally been noticed to arise 
from the first ring of the trachea. 
Constrictor pharyngis medius* is of a trian- 
gular form, fixed by its apex to the hyoid bone 
and by an extensive base to the ian 
behind : its origin is received into the ang 
formed by the greater and smaller cornua of 
os hyoides, to which processes the muscular 
fibres are attached as well as to the lower part 
of the stylo-hyoid ligament: the origin extends 
along the greater cornu quite to its posterior 
extremity, and is concealed by the hyo-glossus 
muscle, the lingual artery intervening: from 
this contracted commencement the middle con- 
strictor spreads widely over the back of the 
pharynx, the superior fibres obliquely ascend- 
ing towards the basilar process of the occipital 
bone, to the spine of which they are connected 
through the medium of the raphé, the muscle 
itself rarely reaching so high; the middle fibres 
take a more or less transverse direction, while 
the inferior descend under cover of the inferior 
constrictor: the whole muscle is inserted, wi 
its fellow from the opposite side, into 
raphé. After emerging from beneath the hyo- 
glossus it is related to the external carotid ar 
tery and superior laryngeal nerve laterally, and 
to the aoe ait column behind: by its internal 
surface it overlaps the superior constrictor, at 
is applied upon the stylo- and palato-pharyng 
muscles and the mucous membrane. Near th 
great cornu of the hyoid bone the stylo-phi 
ryngeus muscle insinuates itself beneath 
upper border, separating it from the superi 
constrictor. 
Constrictor pharyngis superior,;> : 
teral in shape ood enelicaiad from its ¥ 
numerous attachments. The fibres of | 
muscle are paler and it is altogether thinner t 
the two former: it arises, firstly, by short ter 
nous fibres from the lower half of the pos 
edge of the internal pterygoid plate and its 
mular process ; secondly, from an aponeut 
described as the inter- or pterygo-maxillary | 
ment common to it and the buccinator mu 
and which stretches from the inner pteryg 
late to the posterior extremity of the aly 
rder of the inferior maxillary bone; thin 
from the back part of the mylo-hyoid 
; Brashear r 
+ Cephalo- pharyngeus, pterygo -f 
mylo-pharyngeus, glosso-pharyngeus, 
