948 
they become flaccid, and are loosely applied to 
the posterior surface of the larynx, and so con- 
tinued into the @sophagus: if examined from 
behind, the pharynx is seen to be of great 
breadth at the base of the skull, but narrows 
until opposed to the buccal cavity, where it 
again widens to contract somewhat abruptly at 
its termination : its lateral relations to the ca- 
rotid vessels and nerves of the neck have been 
considered in the descriptions of the constrictor 
muscles. 
3. The cavity and its openings.—The interior 
of the pharynx exhibits a cavity of considerable 
size, which is continuous with those of the 
nasal fossee and mouth anteriorly and the canal 
of the esophagus below. To study the varying 
dimensions of this cavity and the different 
openings which communicate with it, the pha- 
rynx must be slit up posteriorly and in the 
median line ; its greatest breadth is behind the 
mouth, the buccal portion, which may be mea- 
sured by the interval between the posterior ex- 
tremities of the alveolar border of the lower 
jaw, and is rather more than two inches ; thence 
narrowing upwards, the internal pterygoid plates 
will by their distance from each other, which 
is about one inch, give the diameter of the 
cavity at its nasal portion, while the distance 
between the posterior edges of the ale of the 
thyroid cartilage will denote its breadth at the 
inferior or laryngeal portion : the antero-poste- 
rior diameter can vary but little, in consequence 
of the relation which the vertebral column has 
to the pharynx behind: during the act of deglu- 
tition these measurements are of course altered, 
but there is much less change of form in the 
upper or nasal portion of the cavity than in the 
rest of its extent. Dropping into the cavity 
from before backwards and from above down- 
wards is the velum palati with the uvula de- 
pending from the centre of its posterior border : 
above this moveable curtain are seen the poste- 
rior openings of the nose with its median sep- 
tum, the vomer: these are situated between 
the internal pterygoid plates, extend upwards 
to the base of the skull, and are limited below 
by the velum; they are quadrilateral in their 
outline and continued into the upper part of 
the pharyngeal cavity; a little way within the 
nasal fosse and along their outer walls are seen 
the meatuses of the nose and the posterior 
edges of the inferior turbinated bones; pro- 
longing these latter backwards by an imaginary 
line, we are brought to the openings of the 
Eustachian tubes; they are two narrow ellipti- 
cal fissures, their long diameters, about three- 
eighths of an inch, directed from above down- 
wards, and situated one on either side of the 
pharynx above the soft palate, and impinging 
the posterior edges of the internal pterygoid 
plates; they look forwards and inwards towards 
the inferior and middle meatuses of the nose, 
and are marked by prominent and rounded 
margins internally; an accurate knowledge of 
their relation to the nasal fosse is of practical 
use in directing a probe or syringe into their 
canals ; behind the openings of the Eustachian 
tubes are the longitudinal sulci which lead up- 
wards and backwards toa cul-de-sac that occu- 
PHARYNX. 
sae the angle formed by the sudden bending 
orward of the aponeurosis of the pharynx 5 
below the velum is the posterior constricted 
aperture of the mouth, which will be again 
referred to in the description of the soft palate; 
it is limited above by the velum, below by the 
base of the tongue, and laterally by the poste- 
rior pillars of the fauces ; the uvula depending 
from the velum centrally gives it a double 
arched outline above, but it is capable of as- 
suming changes of form by the varied move-~ | 
ments of its boundaries, which are especially 
concerned in deglutition; below the isthmus 
faucium and behind the base of the tongue is 
the superior aperture of the larynx, surmounted 
in front by the epiglottis; it is a tri 
opening, the base directed forwards, and it has. 
also an oblique direction from above down- 
wards and from before backwards ; it is gene~ 
rally completely closed during deglutition by: 
the epiglottis being forced down upon it; on 
either side of the posterior surface of the larynx, 
between the thyroid and cricoid cartilages, are 
two gutters which lead sommes to the 
cesophageal opening of the pharynx; this " 
ing bas iis jong diameter se pre < to sid ein 
the flaccid state of its walls, but assumes a 
circular form when distended by the passage of 
food through it. : 
4. Mucous membrane and glands.—The inte- 
rior of the pharynx is lined by a mucous mem- 
brane continuous with that investing the several 
cavities which open into it; it is of a reddish: 
colour, and adherent to the muscular parietes 
by a thin submucous areolar tissue; from co- 
vering the back part and sides of the interior of 
the pharynx, it is to be traced along the under 
surface of the basilar process united to the 
periosteum through the medium of its sub-— 
mucous tunic, which at this part acquires co 
siderable thickness, and is occasionally the se 
of polypus; laterally and above it is ref 
over the guttural orifice of the Eustachian 
enters the canal, and is conducted by it to the 
cavity of the tympanum, forming an exceed 
ingly thin lining to both; continuous with th 
mucous membrane, investing the upper su 
of the velum, it passes through 
nasal openings into the nose; it may e 
traced through the isthmus faucium, coverin; 
the under surface of the velum and poste: 
pillars of the fauces, to be continuous with th 
membrane of the buccal cavity, while more 
teriorly, after assisting to form the aryten 
epiglottidean folds of the laryngeal mucot 
membrane, it is reflected over the poster 
surface of the larynx, to which it is connec! 
so loosely by an areolar tissue as to be throy 
into longitudinal folds, a provision for the di 
tation of this of the pharynx d ne p 
sage of the ane lastly, it is coniila into 
cesophagus. The mucous membrane above 
velum palati, upon its upper surface and wit 
the Eustachian tubes, is coated with epitl 
risms, corresponding in this res : 
rrhich lines the greater part of ihe neal cavitit 
while below the velum the epithelium assut 
the lamelliform or scaly character. Noy 
cous Memprane.) As it invests the up} 
