THE MUSCLES OF THE PHARYNX 163 



and meet behind in the median line; the lowest are beneath 

 the inferior constrictor, the highest overlap the superior con- 

 strictor, the intermediate ones are transverse. The stylo- 

 pharyngeus muscle separates this from the superior constrictor. 



Fibers may come from the hyoid body, tongue, or mylohyoid 

 ridge; a frequent slip from the lateral thyrohyoid ligament 

 is the M. syndesmopharyngeus. 



Superior Constrictor (cephalopharyngeus). Origin, side of the 

 tongue, mucous membrane of the mouth, alveolus at the end 

 of the mylohyoid ridge, pterygomaxillary ligament, hamular 

 process, and lower third of the posterior margin of the internal 

 pterygoid plate; the fibers curve back and insert by blending 

 with the opposite muscle or end in the aponeurosis which 

 fixes the pharynx to the basilar process. Of all the constrictors, 

 only the upper half of this muscle ends in a raphe (linea alba). 

 The upper margin curves around the levator palati and Eus- 

 tachian tube; the space intervening, closed by fibrous membrane 

 is the sinus of Morgagni. 



These muscles are covered externally by dense connective 

 tissue, which is prolonged forward to the pterygomaxillary 

 ligament, and is continuous with the membrane over the 

 buccinator muscle ; hence it is called the buccopharyngeal fascia. 

 Next come the muscular layers, next the pharyngeal aponeu- 

 rosis, and next the mucous membrane. 



The M . stylopharyngeus rises from the inner surface of the 

 styloid process near the root, passes down and in under cover 

 of the middle constrictor, joined by the palatopharyngeus, 

 and ends on the superior and posterior borders of the thyroid 

 cartilage and lateral wall of the pharynx. 



The M. palatopharyngeus will be described with the palatal 

 muscles. 



Varieties. Splitting or doubling or a division into three 

 parts; supernumerary elevators are common, passing to the 

 constrictors or fibrous wall of the pharynx; from the petrous 

 portion or vaginal process = petropharyngeus, from the spine 

 of the sphenoid = sphenopharyngeus, from the hamular pro- 

 cess = pterygopharyngeus cxtcrnus, from the basilar process = 

 occipitopharyngeus, from the mastoid process (rare) = pharyngo- 

 mastoidcus; a small slip to the raphe from the pharyngeal 

 spine = azygospharyngcus. 



