PHARYNX. 



947 



and, lastly, is said to arise from the side of the 

 tongue near its base : this lingual origin is con- 

 sidered by some anatomists as a part of the 

 genio-hyo-glossus muscle :* arising thus, the 

 superior constrictor winds round the pharynx 

 and is inserted into the cephalo-pharyngeal 

 aponeurosis, upon which it is placed, and joins 

 with its fellow from the opposite side at the 

 median raphe. The superior fibres make a 

 semicircular sweep upwards towards the spine 

 of the basilar process, to which they are con- 

 nected by the raphe : the rest pass more trans- 

 versely to their insertion and are partially over- 

 lapped by the middle constrictor: between the 

 upper border of this muscle and the base of 

 the skull the pharyngeal aponeurosis is left un- 

 covered by muscular fibres. The superior 

 constrictor corresponds posteriorly to the cer- 

 vical vertebras, and is separated laterally from 

 the internal pterygoid by a triangular space 

 which is occupied by the internal carotid ar- 

 tery, internal jugular vein, and the eighth and 

 ninth pairs of nerves : the stylo-pharyngeus 

 muscle is also related to its outer side before it 

 descends beneath the middle constrictor: by its 

 internal surface it is applied upon the levator 

 palali and palato-pharyngeus muscles, the mu- 

 cous membrane and the tonsil. 



The muscular layer thus formed round the 

 pharynx is of varying thickness, the greatest 

 strength prevailing behind the buccal cavity, 

 where the inferior constrictor, in itself the 

 strongest of these muscles, overlaps the middle: 

 on the other hand, there is but little occa- 

 sion for muscular action behind the nasal 

 fossae, so we find, in accordance with this 

 circumstance, a greater delicacy in the fibres 

 of the superior constrictor and a defici- 

 ency of muscle altogether higher up: pro- 

 bably, also, the overlapping of these muscles 

 from below upwards and the oblique direction 

 of many of their fibres have reference to the 

 downward passage of the food. The margins 

 of the constrictors, as these muscles lie on each 

 other, are not very distinct, particularly towards 

 the back part of the pharynx. Additional mus- 

 cular slips have occasionally been observed by 

 different anatomists, which may be briefly no- 

 ticed : 1. fibres from the petrous process of 

 the temporal bone to pass downwards and back- 

 walds ; 2. from the basifar process directed 

 inwards ; 3. from the internal pterygoid plate 

 and hamular process directed downwards and 

 inwards ; 4. from the spinous process of the 

 sphenoid and from the cartilaginous portion of 

 the Eustachian tube. 



Use. Besides constricting the cavity of the 

 pharynx, the inferior and middle constrictors 

 can raise the larynx and carry it backwards, 

 the latter through the medium of the os hyoides. 



The extrinsic muscles of the pharynx are two 

 on either side, the stylo- and palato-pharyngei. 



* Cruveilhier says " that those fibres of the 

 genio-hyo-glossus, which occupy the interval be- 

 tween the os hyoides and the stylo-^lossus, cover 

 the corresponding portion of the pharynx, or rather 

 the amygdaloid excavation." Valsalva and San- 

 torini regard these fibres as forming a distinct 

 muscle, and name it the glosso-pharyngeus. 



Stt/lo-pluiryngeus. This is a long slender 

 muscle, broader below than above, and arises 

 from the inner side of the styloid process at 

 its base, and from the neighbouring part of the 

 vaginal process : it descends inwards and for- 

 wards towards the greater cornu of the os 

 hyoides, and expanding insinuates itself be- 

 neath the upper edge of the middle constrictor 

 muscle to be applied upon the mucous mem- 

 brane of the pharynx : it is inserted with the 

 palato-pharyngeus into the posterior border of 

 the thyroid cartilage : soon after its origin it 

 passes with the stylo-glossus muscle between 

 the external and internal carotid arteries, lying 

 upon the latter and the internal jugular vein : 

 a particular feature in this muscle is its close 

 relation to the glosso-pharyngeal nerve, which 

 winds round its lower border from behind for- 

 wards: as it descends, its next relation is the 

 side of the superior constrictor, and passing 

 between it and the constrictor medius it is 

 applied upon the mucous membrane of the 

 pharynx. 



Use. The stylo-pharyngei raise and widen 

 the pharynx, preparing it for the reception of 

 the food : they are important muscles in deglu- 

 tition : the larynx is also raised by them. 



Palato-pliaryngeus. This muscle will be 

 again referred to as belonging to the palate : its 

 fibres are contained in the fold of mucous 

 membrane known as the posterior pillar of the 

 fauces: it expands upwards to the soft palate, 

 and downwards to the pharynx under the supe- 

 rior constrictor : it descends to spread its fibres 

 on the mucous membrane, and is inserted with 

 the stylo-pharyngeus into the posterior border 

 of the thyroid cartilage. 



2. General review of the attachments of the 

 pharynx. By referring to the foregoing de- 

 scriptive anatomy of its aponeurosis and mus- 

 cles, the pharynx will be seen to form from 

 one-half to two-thirds of a vertically elongated 

 cylinder, open in front; and although before 

 terminating, the interior of the pharynx is con- 

 verted into a complete canal, it is so only by 

 the relation of a totally distinct organ, viz. the 

 larynx. Descending perpendicularly from the 

 base of the skull to the lower border of the 

 cricoid cartilage, the pharynx is applied evenly 

 to the anterior aspect of the bodies of the cer- 

 vical vertebra and deep muscles of the neck, 

 having a remarkably loose areolar tissue inter- 

 vening, important as preserving to it a perfect 

 freedom of motion, while, by its anterior edges, 

 it is fixed to the internal pterygoid plates, to 

 the pterygo-maxillary ligaments, by means of 

 which it is continuous with the lateral walls of 

 the mouth, to the inferior maxillary bone, the 

 sides of the tongue and cornua of the os hyoides, 

 thus forming behind the nasal and buccal cavi- 

 ties a large pouch, whose parietes being con- 

 stantly strained apart by these attachments, 

 preserve a perfectly free cavity, a circumstance 

 of considerable importance with reference to 

 the continual passage of air to and from the 

 respiratory apparatus : continuing downwards, 

 the pharynx next embraces the sides of the 

 thyroid and cricoid cartilages, but as there is 

 no longer occasion for this tension of its walls, 



3 P 2 



