PHARYNGEAL REGION". 2C3 



laginous surface behind it, nearly as far as its posterior border, and to the 

 inferior cornu. From these attachments, the fibres spread backwards and 

 inwards, to be inserted into the fibrous raphe in the posterior median line of the 

 pharynx. The inferior fibres are horizontal, and continuous with the fibres of 

 the oesophagus ; the rest ascend, increasing in obliquity, and overlap the Middle 

 constrictor. The superior laryngeal nerve passes near the upper border, and the 

 inferior or recurrent laryngeal beneath the lower border of this muscle, previous 

 to their entering the larynx. 



Relations. It is covered by a dense cellular membrane which surrounds the 

 entire pharynx. Behind, it lies on the vertebral column and the Longus colli. 

 Laterally, it is in relation with the thyroid gland, the common carotid artery, and 

 the Sterno-thyroid muscle. By its internal surface, with the Middle constrictor, 

 the Stylo-pharyngeus, Palato-pharyngeus, and the mucous membrane of the 

 pharynx. 



The Middle Constrictor is a flattened, fan-shaped muscle, smaller than the pre- 

 ceding, and situated on a plane anterior to it. It arises from the whole length of 

 the greater cornu of the hyoid bone, from the lesser cornu, and from the stylo- 

 hyoid ligament. The fibres diverge from their origin ; the lower ones descending 

 beneath the Inferior constrictor, the middle fibres passing transversely, and the 

 upper fibres ascending to cover in the Superior constrictor. It is inserted into 

 the posterior median fibrous raphe, blending in the middle line with the fibres of 

 the opposite muscle. 



Relations. This muscle is separated from the Superior constrictor by the glosso- 

 pharyngeal nerve and the Stylo-pharyngeus muscle ; and from the Inferior con- 

 strictor, by the superior laryngeal nerve. Behind, it lies on the vertebral column, 

 the Longus colli, and the Eectus anticus major. On each side it is in relation 

 with the carotid vessels, the pharyngeal plexus, and some lymphatic glands. Near 

 its origin, it is covered by the Hyo-glossus, from which it is separated by the 

 lingual artery. It covers in the Superior constrictor, the Stylo-pharyngeus, the 

 Palato-pharyngeus, and the mucous membrane. 



The /Superior Constrictor is a quadrilateral muscle, thinner and paler than the 

 other constrictors, and situated at the upper part of the pharynx. It arises from 

 the lower third of the margin of the internal pterygoid plate and its hamular 

 process, from the contiguous portion of the palate bone and the reflected tendon of 

 the Tensor palati muscle, from the pterygo-maxillary ligament, from the alveolar 

 process above the posterior extremity of the mylo-hyoid ridge, and by a few fibres 

 from the side of the tongue in connection with the Genio-hyo-glossus. From these 

 points, the fibres curve backwards, 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. Its superior fibres arch beneath the Levator 

 palati and the Eustachian tube, the interval between the upper border of the 

 muscle and the basilar process being deficient in muscular fibres, and closed by 

 fibrous membrane. 



Relations. By its outer surface, with the vertebral column, the carotid vessels, 

 the internal jugular vein, the three divisions of the eighth and ninth nerves, the 

 Middle constrictor which overlaps it, and the Stylo-pharyngeus. It covers the 

 Palato-pharyngeus and the tonsil, and is lined by mucous membrane. 



The Stylo-pharyngeus is a long, slender muscle, round above, broad and thin 

 below. It arises from the inner side of the base of the styloid process, passes 

 downwards along the side of the pharynx between the Superior and Middle con- 

 strictors, and, spreading out beneath the mucous membrane, some of its fibres are 

 lost in the Constrictor muscles, and others, joining with the Palato-pharyngeus, 

 are inserted into the upper border of the thyroid cartilage. The glosso- pharyngeal 

 nerve runs on the outer side of this muscle, and crosses over it in passing forward 

 to the tongue. 



Relations. Externally, with the Stylo-glossus muscle, the external carotid 

 artery, the parotid gland, and the Middle constrictor. Internally, with the internal 



