952 THE OEGAys OF DIGESTION 



of the palato-pharyngeus and are inserted into the posterior border of the thyroid 

 cartihige ( htr. ooOa): tin- rest blend with the constrictors. 



The palato-pharyngeus is described with tlie muscles of the soft palate. 



The niu.scular coat of tlie pharynx is svipplied by the pharyngeal plexus and 

 the external and recurrent laryngeal nerves. The stylo-jjliaryngeus is sujjplied by 

 the gloss()-])haryngeal nerve. 



Relations.-^The pharynx is loosely connected by areolar tissue with the pre- 

 vertebral fascia, the longus colli, and the rectus capitis anticus major muscles, 

 and vertebral colunni. Laterally, it is in relation with the styloid process and its 

 muscles, the ninth, tenth, and eleventh cranial nerves, the superior laryngeal nerve 

 and its internal and external laryngeal branches, the parotid and thyroid glands, 

 the sheath of the carotid vessels, the pharyngeal plexus of nerves, the ascending 

 pharyngeal artery, and the ascending palatine branch of the facial artery; above, 

 it is separated from the ramus of the mandible and internal pterygoid muscle by a 

 cellular interval; and beneath its investing fascia there is a plexus of veins. 



The interior of the pharynx, viewed from behind, presents the seven open- 

 ings already named. At its upper and back part the mucous membrane forms a 

 rounded projection which corresponds to the anterior recti muscles, and on each 

 side of this it sinks backwards, beneath the tip of the petrous portion of the tem- 

 poral bone, and l)ehind the Eustachian tube, to form a ad-de-sac known as the 

 pharyngeal recess, or fossa of Rosenmiiller. 



In the roof of the cavity just below the body of the occipital bone and in the 

 middle line, the jnucous membrane dips into a little pouch with a contracted orifice, 

 the pharyngeal bursa, wdiich is easily demonstrated in the foetus and young child, 

 but commonly entirely disapj^ears in the adult. 



Embedded in the roof of the pharynx, in front of the pharyngeal l)ursa, and 

 between the oritices of the Eustachian tul)es, there is a collection of lymphoid 

 follicles which is known as the pharyngeal tonsil, or Luschka's tonsil. Tliis por- 

 tion of the naso-pharynx is exceedingly liable to become swollen and chronically 

 thickened in naso-pharyngeal catarrh. 



TRF OESOPHAGUS 



The CESophagus is that portion of the alimentary tract which extends between 

 the pharynx and the stomach. It is more constricted than the rest of the canal, 

 being narrowest at its commencement opposite the sixth cervical vertebra and lower 

 border of the cricoid cartilage. It is again somewhat contracted in its passage 

 through the dia])hragm, which is opposite the upper border of the eleventh thoracic 

 vertebra. It is nine or ten inciies (25 cm.) in length, and in its course downwards 

 follows the curv(^s of the vertebral colunm, until it finally ])asses forwards in front 

 of, and slightly to the left of the aorta to gain the oesophageal opening in the dia- 

 phragm. In addition to these curves it presents two lateral cur^^atures, one convex 

 towards the left side at the root of the neck and in the upper part of the thorax, 

 and the other concave towards the left in the lower part of the thorax where it leaves 

 the vertebral column. It lies in the middle line at its commencement opposite the 

 sixth cervical vertebra, and again, at a lower level, opposite tlu^ fifth thoracic vertebra. 



Relations in the neck. — The oesophagus has in front of it the trachea, the 

 ])()sterior portion of the left lateral lol^e of the thyroid gland, and the left recurrent 

 laryngeal nerve, l)ranches of the inferior thyroid artery and the carotid sheath. 

 Behind, it rests upon the vertebral column, the left longus colli muscle, and pre- 

 vertebral fascia. 



On its right side are, placed the right carotid and right recurri'nt nerve; and on 

 the left side the left inferior thyroid vessels, left carotid artery, left subclavian, 

 and the thoracic duct. The recurrent nerves pass upwards on each side to gain the 



