396 



THE MUSCLES AND FASCIA 



The Middle constrictor (m. constrictor pharyngis medius) is a flattened, fan- 

 shaped muscle, smaller than the preceding. It arises from the whole length of 

 the upper border of the greater cornu of the hyoid bone, from the lesser cornu, 

 and from the stylohyoid ligament. The fibres diverge from their origin, the lower 

 ones descending beneath the Inferior constrictor, the middle fibres passing trans- 

 versely, and the upper fibres ascending and overlapping the Superior constrictor. 

 The muscle is inserted into the posterior median fibrous raphe, blending in the 

 middle line with its fellow of the opposite side. 



Relations. Between this muscle and the Superior constrictor are the glossopharyngeal nerve, 

 the Stylopharyngeus muscle and the stylohyoid ligament; and between it and the Inferior con- 

 strictor is the superior laryngeal nerve. Behind, the Middle constrictor lies on the vertebral 



column, the Longus colli, and the Rectus 

 capitis anticus major. On each side it is in 

 relation with the carotid vessels, the pharyn- 

 geal plexus, and some lymph nodes. Near 

 its origin it is covered by the Hyoglossus, the 

 lingual vessels being placed between the two 

 muscles. It lies upon the Superior constric- 

 tor, the Stylopharyngeus, the Palatopharyn- 

 geus, the fibrous coat, and the mucous 

 membrane of the pharynx. 



The Superior constrictor (m. con- 

 strictor pharyngis superior] is a quadri- 

 lateral muscle, thinner and paler than 

 the other Constrictors, and situated 

 at the upper part of the pharynx. It 

 arises from the lower half of the posterior 

 margin of the internal pterygoid plate 

 and its hamular process, from the con- 

 tiguous portion of the palate bone and 

 the reflected tendon of the Tensor palati 

 muscle, from the pterygomandibular 

 ligament, from the alveolar process 

 above the posterior extremity of the 

 mylohyoid ridge, and by a few fibres 

 from the side of the tongue. From 

 these points the fibres curve backward, 

 to be inserted into the median raphe', 

 being also prolonged by means of a 

 fibrous aponeurosis to the pharyngeal 

 spine on the basilar process of the occipital bone. 1 The superior fibres arch beneath 

 the Levator palati and the Eustachian tube. The interval between the upper 

 border of the muscle and the basilar process is deficient in muscle fibres and is 

 closed by a portion of the pharyngeal aponeurosis (fascia pharyngobasilaris). 

 This interval is known as the sinus of Morgagni. 



Relations. By its superficial surface the Superior constrictor is in relation with the prever- 

 tebral fascia and muscles, the vertebral column, the internal carotid and ascending pharyngeal 

 arteries, the internal jugular vein and pharyngeal venous plexus, the glossopharyngeal, vagus, 

 spinal accessory, hypoglossal, lingual, and sympathetic nerves, the Middle constrictor and 

 Internal pterygoid muscles, the styloid process, the stylohyoid ligament, and the Stylopharyn- 

 geus. By its deep surface, it is in relation with the Palatopharyngeus, the tonsil, the fibrous 

 coat, and the mucous membrane of the pharynx. 



FIG. 306. Muscles of the pharynx. External view. 



1 Accessory bundles of origin sometimes arise from the margins of the middle lacerated foramen and descend 

 to blend with the main muscle mass. 



