THE MUSCLES OF THE SOFT PALATE. 307 



connective tissue, which is but loosely attached to the adjacent prevertebral fascia 

 (p. 298). This layer is stronger above than below, and is prolonged forwards over 

 the lateral part of the superior constrictor to the pterygo-maxillary ligament, where 

 it becomes continuous with the membrane covering the buccinator muscle, whence 

 the whole structure is named the bucco-pharyngeal fascia. 



The stylo-pharyngeus (fig. 279, 3), larger and longer than the other styloid 

 muscles, arises from the inner surface of the styloid process near the root, and pro- 

 ceeding downwards and inwards to the side of the pharynx, passes under cover of 

 the middle constrictor muscle, where it gradually expands, and being joined by the 

 palato-pharyngeus, ends on the superior and posterior borders of the thyroid carti- 

 lage, and in the lateral wall of the pharynx. 



Relations. The external surface of this muscle is, in the upper part of its extent, in 

 contact with the styloid process and the external carotid artery ; in the lower, with the 

 middle and inferior constrictors of the pharynx. Internally it rests on the internal carotid 

 artery and superior constrictor, and lower down on the mucous membrane of the pharynx. 

 The glosso-pharyngeal nerve crosses over the muscle in turning forwards to the tongue. 



Varieties. Splitting or doubling of the stylo-pharyngeus is often met with ; a division 

 into three parts has also been observed. 



Supernumerary elevator muscles of the pharynx are not unfrequently present, arising from 

 a neighbouring part of the base of the skull, and inserted variably into one or other of the 

 constrictors, or passing between those muscles to the fibrous layer of the pharynx. Their 

 most frequent origin is from the under surface of the petrous bone in front of the carotid 

 canal or from the vaginal process of the temporal bone {petro-pliaryngeus), but they also 

 occur arising from the spine of the sphenoid (spheno-pharyngeus), from the hamular process 

 (pterygo-pharyng&us externus), or farther back, from the basilar process (pccipito-pharyngeus), 

 or very rarely from the mastoid process {pliaryngo-mastoideus). Belonging to the same group 

 is the azygos pharyngia, a small median slip sometimes present, arising from the pharyngeal 

 tubercle of the occipital bone, and descending to the raphe or the posterior wall of the 

 pharynx. 



Nerves. The constrictor muscles are supplied by the pharyngeal plexus, their motor fibres 

 being derived from the bulbar portion of the spinal accessory nerve, and in the case of the 

 middle constrictor perhaps also from the glosso-pharyngeal. The inferior constrictor receives 

 branches in addition from the external and inferior laryngeal nerves. The stylo-pharyngeus 

 is innervated by the glosso-pharyngeal. 



THE MUSCLES OP THE SOFT PALATE. 



The soft palate (velum pendulum palati) is a moveable curtain, continued 

 backwards from the hard palate. It presents posteriorly a free pendulous margin, 

 prolonged in the middle into a conical process, the uvula, and at each side into a 

 prominent curved fold, the posterior pillar of the fauces, which runs downwards and 

 backwards on the side wall of the pharynx, while from the base of the uvula and the 

 under surface of the soft palate another fold, the anterior pillar of the fames, descends 

 to the tongue ; between the two pillars on each side is lodged the tonsil. The con- 

 stricted passage between the anterior pillars, leading from the mouth to the pharynx, 

 is called the isthmus of the fauces. The soft palate is acted on by five pairs of 

 elongated muscles, two superior, one intermediate, and two inferior. 



The palato-glossus muscle, or constrictor isthini faucium, occupies the 

 anterior pillar of the fauces. Superiorly it is placed below all the other muscles of 

 the palate, and its fibres are continuous with those of its fellow of the opposite side ; 

 inferiorly it enters the side of the tongue, where it becomes continuous with the 

 transverse fibres of that organ. 



Behind and continuous with the fibres of the palato-glossus are some thin bundles of 

 muscular fibres which ascend from the side of the tongue and are lost over the outer surface 

 of the tonsil. They were named amygdalo-glossus by Broca. 



The palato-pharyngeus arises in the soft palate in two layers which embrace 

 the Ipvator palati and azygos uvulae muscles. The superficial or upper layer con- 



VOL. II. X 



