60 CLINICAL APPLIED ANATOMY. 



parts of the body exposed to friction and contamination with 

 damp, infected soil. 



Infection with Trichina spiralis occurs as the result of eating 

 measly pork. The investing capsule having been dissolved by 

 the gastric juice, the worms mature and breed in the upper part 

 of the small intestine. It is said the adult female may partially 

 penetrate the intestinal wall, and actually deposit her ova in the 

 lymphatic sinuses of the bowel. Whether the lancet-shaped 

 embryos thus reach the spaces or penetrate the bowel from its 

 interior by their own endeavours is immaterial, they become 

 widely disseminated. Two views are held as to the anatomical 

 route by which this dissemination occurs. One idea is that 

 the embryos, entering the lymph spaces, are carried along the 

 thoracic duct to the veins, traverse the heart and lungs, and 

 are ultimately carried to the muscles by the arterial blood stream ; 

 the other view is that, after penetrating the wall of the bowel, 

 they gain access to the root of the mesentery, or cross the 

 peritoneal cavity, and having thus reached the subperitoneal 

 connective tissue, migrate along its planes to the interstitial tissue 

 of the muscles, and in smaller numbers to the subcutaneous 

 tissues of the body. The muscles most affected are, in order, 

 the diaphragm, especially its crura ; the intercostals ; the cervical 

 and laryngeal muscles ; the muscles of the eye ; the biceps and 

 triceps. In the larger muscles the parasites are most numerous 

 near the tendinotfs ends, possibly the lateral pressure during 

 contraction is less at these points. The parasites lie between the 

 individual muscle fibres, and are not actually within the sarco- 

 lemma as was formerly supposed. 



The muscles infected become swollen, tender and hard. 

 Implication of the diaphragm and intercostals interferes with 

 respiratory movements, whilst infection of the masticatory 

 muscles, the tongue, pharynx and larynx causes the actions of 

 chewing, talking and swallowing to be excessively painful. The 

 patient is quite crippled by the inflammation of the muscles of 

 the limbs and trunk, and assumes a semiflexed attitude to 

 relieve muscular tension as far as possible. The oedema which 



