THE PHARYNX. 819 



Development. In mammalia, according to Miiller and Weber, the salivary glands, 

 as shown in the case of the parotid gland in the embryo of the sheep, first appear in 

 the form of a simple canal with bud-like processes lying in a blastema, and communi- 

 cating with the cavity of the mouth. This canal becomes more and more ramified to 

 form the ducts, whilst the blastema soon acquires a lobulated form, corresponding with 

 that of the future gland, and at last wholly disappears, leaving the branched ducts, 

 with their blood-vessels and connecting tissues. The submaxillary gland is said to 

 be the first formed ; then the sublingual and the parotid. 



THE PHARYNX. 



The pharynx is that part of the alimentary canal which unites the cavi- 

 ties of the mouth and nose to the oesophagus. It extends from the base 

 of the skull to the lower border of the cricoid cartilage, and forms a sac 

 open at the lower end, and imperfect in front, where it presents apertures 

 leading into the nose, mouth and larynx. 



The velum pendulum palati projects backwards into the pharynx, and 

 during the passage of the food completely separates an upper from a lower 

 part by means of the contraction of the muscles connected with it which are 

 placed in the posterior pillars of the fauces. Seven openings lead into the 

 cavity of the pharynx ; viz., above the velum, the two posterior openings 

 of the nares and, at the sides the apertures of the Eustachian tubes ; while, 

 below the velum, there is first the passage leading from the mouth, then the 

 superior opening of the larynx, and lastly the passage into the oesophagus. 



The walls of the pharynx consist of a fascia or layer of fibrous tissues, 

 named the pharyngeal apoueurosis, dense at its upper part but lax and 

 weak below, surrounded by muscles, and lined by a mucous membrane. 

 At its upper end this fibrous wall is attached to the posterior margin of the 

 body of the sphenoid bone, and passes outwards to the petrous portion of 

 the temporal. It is strengthened in the middle line by a strong band de- 

 scending between the recti antici muscles from a part of the basilar process 

 which often presents a marked tubercle. 



The pharynx is usually described as attached superiorly to the basilar process 

 of the occipital bone ; it is certain, however, from dissections in both young and old 

 subjects, that the recti capitis antici muscles come quite forward to the anterior ex- 

 tremity of the basilar process ; that the posterior wall of the pharynx at its upper end 

 forms a cul-de-sac on each side opposite the tip of the petrous bone, and lies in a 

 curve, with its convexity forwards, in front of the recti muscles ; and that the only 

 connection of the pharynx with the occipital bone is by means of the mesial band, 

 which has been described, and which forms a cranio-pharyngeal ligament. The 

 tubercle from which this band principally springs is sometimes named tuberculum 

 pharyngeum, 



Behind, the wall of the pharynx is loosely connected by areolar tissue 

 to the prevertebral fascia covering the bodies of the cervical vertebrae and 

 the muscles which rest upon them. At the sides, the walls have similar 

 connections, by loose areolar tissue, with the styloid process and its muscles, 

 and with the large vessels and nerves of the neck. In front, they are 

 attached in succession to the sides of the posterior nares, the mouth and 

 the larynx. Thus, commencing above by a tendinous structure only, at the 

 petrous portion of the temporal bone and the Eustachian tube, the walls are 

 connected by means of muscle and fibrous membrane, first, with the inter- 

 nal pterygoid plate, then with the pterygo-maxillary ligament, and next 

 with the mylo-hyoid ridge of the lower jaw ; below this, they are attached 



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