952 THE ORGANS OF DIGESTION. 



is found in the tonsils. Across the back part of the pharyngeal cavity, between the 

 two Eustachian tubes, a considerable mass of this tissue exists, and has been named 

 the pharyngeal tonsil. Just below this in the middle line is the orifice of an 

 irregular, flask-shaped recess of the mucous membrane, extending up as far as 

 the basilar process of the occipital bone. It is known as the bursa pharyngea, 

 and is the remains of the diverticulum of the alimentary canal, which is con- 

 cerned in the development of the pituitary body (which see). It is only occa- 

 sionally present in the adult. 



The muscular coat has been already described (page 419). 



Surgical Anatomy. The internal carotid artery is in close relation with the pharynx, so 

 that its pulsations can be felt through the mouth. It has been occasionally wounded by sharp- 

 pointed instruments introduced into the mouth and thrust through the wall of the pharynx. 

 In aneurism of this vessel in the neck the tumor necessarily bulges into the pharynx, as this is 

 the direction in which it meets with the least resistance, nothing lying between the vessel and 

 the mucous membrane except the thin Constrictor muscle, whereas on the outer side there is 

 the dense cervical fascia, the muscles descending from the styloid process, and the margin of the 

 Sterno-mastoid. 



The mucous membrane of the pharynx is very vascular, and is often the seat of inflamma- 

 tion, frequently of a septic character, and dangerous on account of its tendency to spread to the 

 larynx. On account of the tissue which surrounds the pharyngeal wall being loose and lax, the 

 inflammation is liable to spread through it far and wide, extending downward into the posterior 

 mediastinum along the oesophagus. Abscess may form in the connective tissue behind the 

 pharynx, between it and the vertebral column, constituting what is known as post- pharyngeal 

 abscess. This is most commonly due to caries of the cervical vertebrae, but may also be caused 

 by suppuration of a lymphatic gland which is situated in this position opposite the axis, and 

 which receives lymphatics from the nares, or by a gumrna or by acute pharyngitis. The abscess 

 may be most easily evacuated by an incision, with a guarded bistoury, through the mouth. It 

 has recently been proposed to open the abscess aseptically by an incision in the neck behind the 

 Sterno-mastoid. The operation, however, is a difficult one, unless the abscess is pointing later- 

 ally, and does not give such free access to the seat of disease for the removal of necrosed bone, if 

 any exists, and does not appear to present sufficient advantages to warrant its performance. 



Foreign bodies not unfrequently become lodged in the pharynx, and most usually at its 

 termination at about the level of the cricoid cartilage, just beyond the reach of the finger, as the 

 distance from the arch of the teeth to the commencement of the oasophagus is about six 

 inches. 



The position of the openings of the Eustachian tubes should be studied with a view to 

 catheterism of these tubes. This is to be done by introducing the instrument through the 

 anterior nares, so that its points rest on the floor of the nasal cavity close to the septum ; it is 

 then pushed gradually and slowly backward until the posterior wall of the pharynx is reached. 

 Then having been slightly withdrawn so as to free the point from the wall of the pharynx, it is 

 rotated outward and upward, so that the ring of the instrument is turned toward the external 

 ear, and it can then be made to glide into the Eustachian tube. 



THE (ESOPHAGUS. 



The oesophagus, or gullet, is a muscular canal, about nine inches (23 centim.) 

 in length, extending from the pharynx to the stomach. When empty its lumen 

 appears as a transverse slit. Its diameter varies from 1.8 to 2.4 centim. It 

 commences at the upper border of the cricoid cartilage, opposite the iriterverte- 

 bral disk between the fifth and sixth cervical vertebrae, descends along the front 

 of the spine through the posterior mediastinum, passes through the Diaphragm, 

 and, entering the abdomen, terminates at the cardiac orifice of the stomach oppo- 

 site the tenth dorsal vertebra or the intervertebral disk between the tenth and 

 eleventh dorsal vertebrae. The general direction of the oesophagus is vertical, 

 but it presents two or three slight curves in its course. At its commencement it 

 is placed in the median line, but it inclines to the left side as far as the root of 

 the neck, gradually passes to the middle line again, and finally again deviates to 

 the left as it passes forward to the oesophageal opening of the Diaphragm. The 

 oesophagus also presents an antero-posterior flexure, corresponding to the curva- 

 ture of the cervical and thoracic portions of the spine. It is the narrowest part 

 of the alimentary canal, being most contracted at its commencement and at the 

 point where it passes through the Diaphragm. 



Relations. In the neck the oesophagus is in relation, in front, with the 

 trachea, and at the lower part of the neck, where it projects to the left side, with 



