1150 



THE DIGESTIVE SYSTEM. 



Those from the superior part of the posterior wall join a few retro-pharyngeal glands which are 

 found on each side between the pharynx and the rectus capitis anterior muscle. These latter 

 glands, which are large in the child, small in the adult, but apparently always present (Fig. 

 906), are of considerable clinical interest, as they often form the starting-point of post-pharyngeal 

 abscess. For fuller details see section on Lymph Glands. 



The nerves of the pharynx, both motor and sensory, are derived chiefly from the pharyngeal 

 plexus, which is formed by branches of the vagus, glosso-pharyngeal, and sympathetic. The 

 soft palate and the neighbourhood of the palatine tonsil are supplied by the palatine branches 

 of the spheno -palatine ganglion. The tonsil receives a branch from the glosso-pharyngeal direct. 

 The vault of the pharynx, and the region around the orifice of the tuba auditiva, as well as the 

 orifice itself, are supplied by branches from the spheno-palatine ganglion. Finally, the 

 internal laryngeal nerve supplies the mucous membrane of the back of the larynx, where it forms 

 the anterior wall of the laryngeal portion of the pharynx. 



Hyoid bone 



Thyreoid cartilage 



Cricoid cartilage 



Trachea 



(Esophagus 



(ESOPHAGUS. 



The oesophagus or gullet is the portion of the digestive canal which intervenes 

 between the pharynx above and the stomach below. With the exception of the 



pylorus, it is the narrowest, and at the 

 same time one of the most muscular parts 

 of the whole alimentary tube. 



It extends from the termination of the 

 pharynx, at the inferior border of the cricoid 

 cartilage and opposite the sixth cervical 

 vertebra, to the cardiac orifice of the stomach, 

 opposite the eleventh thoracic vertebra. 

 Between those two points it traverses the 

 inferior part of the neck, the whole length of 

 the thorax, and, having pierced .the dia- 

 phragm, it enters the abdomen, and im- 

 mediately afterwards joins the stomach. In 

 its course it does not adhere to the median 

 plane of the body, but twice leaves it, and 

 curves to the left. The first of the curva- 

 tures corresponds to the inferior part of the 

 neck and the superior part of the thorax, 

 * Aperture in diaphragm where the oesophagus projects beyond the 

 left margin of the trachea to the extent 

 of J or J inch (4 to 6 mm.). It returns 

 to the median plane at the level of the 

 fourth thoracic vertebra, posterior to the 

 aortic arch. Lower down, posterior to the 

 pericardium, it again passes to the left, and 

 at the same time forwards, in order to 

 reach the cesophageal opening in the dia- 

 phragm (which is placed anterior to and 

 to the left of the aortic opening), and it 

 maintains this direction until the stomach 

 is reached. It leaves the median plane at 

 the seventh thoracic vertebra, crosses an- 

 terior to the aorta at the level of the 

 eighth thoracic vertebra, and traverses the 

 diaphragm at the level of the tenth. 



In addition to the curvatures just de- 

 THE COURSE OF gcribedj it is a i so curved ^ t he antero- 



posterior direction, in correspondence with 

 the form of the vertebral column, upon which it, in great part, lies. 



In length it usually measures about ten inches (25 cm.). 



Its breadth, where the tube is widest, varies between half an inch (13 mm.) 

 in the empty contracted condition and an inch or more (25 to 30 mm.) in the 

 fully distended state. 



Thoracic duct 



12th thoracic 



vertebra 



Abdominal aorta 



Fio. OOT.- 



