3 I 8 MUSCULAR COATS OF ALIMENTARY CANAL, [sect. 147. 



Fie. 133. 



the region of the anus. Nevertheless, the longitudinal muscular 

 layer beneath the pelvic fascia is thicker, which, according to 

 Treitz, is owing to the additional fibres coming from the fascia, 

 the levator and the coccyx (musculus recto-coccygeus, Treitz), some 

 of which also become intermingled with the circular muscular 

 fibres. 



All the muscles of the proper intestine belong to the smooth or 

 unstriped (vegetative, organic) muscles, as they are termed (see 

 § 29). Their elements, or the fibre-cells, are fusiform, 0*002'" to 

 0*003'", broad in the middle and flattened, 0*06'" to o*i'" long, pale 

 and homogeneous, with a nucleus 0*006'" to o*oi2"' long, o*ooi'" 

 to 0*0028'" broad, which, according to Lehmann, is invisible in 

 muscles which have been macerated in water, and, according to 

 Henle, completely disappears on commencing putrefaction; which 

 phenomenon I am disposed to ascribe to the escape of the nuclei 

 from the fibre-cells, which happens with extreme facility. Many 

 of the fibres are marked with nodular swellings, frequently, also, 

 by zig-zag curvatures, which are especially frequent in alcohol-pre- 

 parations, and occasion the transversely banded appearance of the 



entire fasciculi of such muscles. The 

 fibre-cells of the different muscular 

 strata are ranged alongside each other, 

 and cohere longitudinally and trans- 

 versely, so as to form slender mus- 

 cular bands, which then, being severally 

 enveloped in some connective tissue, 

 and frequently united into thicker 

 bundles, form the thicker or thinner 

 muscular coats of the different regions, 

 which coats are themselves likewise 

 invested by considerable layers of con- 

 nective tissue, and separated from the 

 neighbouring parts. 



The blood-vessels of the smooth 

 muscles are very numerous, and their 

 capillaries, 0*003'" to 0*004'" broad, 

 form a well-characterised network with 

 rectangular meshes. Nothing is known 

 about the lymphatics of the muscles themselves ; and the condition 

 of the nerves is likewise unascertained, except that Echer observed 

 divisions of fine nerve-fibres in the muscular coat of the stomach of 

 the frog and rabbit. 



Blood-vessels of the smooth mus- 

 cular fibres of the intestine, from an 

 injection by Gcrlach. Magnified 45 

 times. 



