i6o6 HUMAN ANATOMY. 



The inferior constrictor (Figs. 1339, '360), the thickest of the three, arises 

 from the posterior part of the outer aspect of the cricoid cartilage, from the oblique 

 line and the triangular surface below and behind it on the thyroid cartilage, including 

 the inferior horn. It overlaps the preceding muscle, its upper fibres reaching to some 

 3 cm. below the base of the skull and the lower ones being nearly horizontal. The 

 median raphe, which receives almost all the fibres, is wanting below. The lowest 

 fibres are circular and continuous with the circular fibres of the gullet. 



The stylo-pharyngeus (Fig. 1361) arises from the inner side of the styloid 

 process near its root and descends to the inter\^al between the superior and middle 

 constrictors near the hyoid bone, where it passes under the latter and ends by expand- 

 ing in the side of the pharynx, some of its fibres going to the posterior border of the 

 thyroid cartilage and others joining the expansion of the palato-pharyngeus. A 

 bundle from the thyroid division passes to the side of the epiglottis, forming on the 

 wall of the pharynx the fold known as the plica pharyyigo-epiglottica. The fibres 

 of the superior constrictor may be inseparable from the upper part of this layer. 



The salpingo-pharyngeus has been described in connection with the levator 

 palati (page 1571). 



Variations. — Additional muscles are very common, being chiefly longitudinal bundles due 

 to splitting of one of the normal muscles, especially the stylo-pharyngeus, or to new bundles of 

 fibres arising from the base of the skull in the vicinity of the upper insertion of the pharyngeal 

 fascia . There may be a pair of occipito-pharyngeal muscles, arising from the occipital bone on 

 either side of the median line and descending to be lost in the posterior pharyngeal wall ; or 

 there may be an azygos muscle instead. Bands may arise at the side from the petrous portion 

 of the temporal bone or the spine of the sphenoid. 



Actions. — The general action of the pharyngeal muscles is sufiliciently evident ; 

 the constrictors decrease the size of the pharynx, probably drawing the larynx upward 

 and backward at the same time. The longitudinal muscles raise the larynx and 

 pharynx, acting chiefly on the latter. 



Vessels. — The arteries of the pharynx are from many sources and are irregu- 

 lar. The chief is the ascending pharyngeal, which runs up near the posterior lateral 

 angle. Occasionally, when enlarged, it is seen pulsating on the posterior wall. 

 Branches from the facial play an uncertain part. The veins form the pharyngeal 

 plexus situated outside of the constrictors and communicating in all directions. The 

 chief outlets are by a pair of veins on each side, one going up to the internal jugular 

 near the base of the skull and the other down to the external jugular or some of its 

 tributaries (Luschka). A submucous plexus is particularly developed in the lower 

 posterior wall, which opens into the pharyngeal plexus by several branches piercing 

 the inferior constrictor. The following are nearly constant : a superior and posterior 

 one near the middle line, one running outward on each side near the back of 

 the thyroid cartilage, forming a part of the origin of the pharyngeal vein, and one 

 passing forward to the superior thyroid vein.' The lymphatics, which are numerous, 

 run in the upper part to the prevertebral nodes and to the deep cervdcal system, as 

 do the lower ones at another level. The presence of lymphatic nodes behind the 

 naso-pharynx is of practical importance, as they are sometimes inflamed and may 

 suppurate. They lie near the fossae of Rosenmiiller. 



Nerves. — The constrictors are supplied by the pharyngeal plexus, the lower 

 receiving fibres also from the recurrent laryngeal. The stylo-pharyngeus is supplied 

 by the glosso-pharyngeal. The nerves of the mucous membrane are from the glosso- 

 pharyngeal, the pneumograstric, and the sympathetic, to a great extent in a plexiform 

 arrangement. 4 



PRACTICAL CONSIDERATIONS : THE PHARYNX. 



The pharynx may be said to present only three sides for consideration, but its 

 continuity above with the nares, anteriorly with the mouth, and below with the ori- 

 fices of the larynx and oesophagus associates it intimately with the diseases of those 

 regions. The naso-pharynx and the laryngeal relations will be considered with the 

 Respiratory Passages (page 1829). 



' Bimar et Lapeyre : Comptes rendus de I'Acad. des Sciences. Paris, tome cv., 1887. 



