88 GENERAL ANATOMY OF THE TISSUES. 



isolated muscles in the human body; as, for example, is the 

 case in the genito-rectal muscles of mammalia, but exist either 

 scattered in the connective tissue, or in the form of muscular 

 membranes. In both cases the bundles are either parallel or 

 interwoven into networks. Their distribution is as follows : 



1 . In the Intestinal canal the smooth muscle forms : first, 

 the tunica musculosa from the lower half of the oesophagus, 

 where smooth bundles are still mingled with transversely 

 striated fibres, as far as the sphincter am interims : secondly, 

 the muscular lavers of the mucous membrane, from the 

 oesophagus to the anus: and thirdly, scattered muscular bundles 

 in the villi. 



2. In the Respiratory organs, a layer of smooth muscles 

 appears in the posterior wall of the trachea, and accompanies 

 the bronchia, even to their finest ramifications, as a complete, 

 circularly fibrous membrane. 



3. In the Salivary glands, this tissue is found solely in 

 "Wharton's duct; and here only scantily, and forming an incom- 

 plete coat. 



4. The Liver has a perfect muscular layer in the gall- 

 bladder, and scattered smooth muscles, also in the ductus 

 choledochus. 



5. The Spleen has this kind of muscle in many animals in 

 its outer coat, and in the trabecule, mixed with connective 

 tissue and elastic fibres. 



6. In the Urinary organs the smooth muscles are found in 

 the calices and pelves of the kidneys, form a complete mus- 

 cular layer in the ureters and urinary bladder, but are only 

 sparingly to be found in the urethra. 1 



7. The Female sexual organs possess smooth muscles in the 

 oviducts, the uterus, where during pregnancy their elements 

 become excessively developed, and attain a length of \" , the 

 vagina, the corpora cavernosa, and in the broad ligaments of 

 the uterus in different places. 



8. In the Male sexual organs they are found in the dartos, 

 between the t. vaginalis communis and propria, in the vas 



1 [Mr. Hancock (On the Anatomy and Physiology of the Male Urethra, London, 

 1852), who had made out the existence of the organic muscular layer in the urethra 

 independently, attrihutes to it much more anatomical and physiological importance. 

 (See helow, § Urinary Organs.) — Eds.] 



