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The muscle fibres encircling the common bile-duct were now cut 
along the long axis of the duct. The mucous membrane of the duct 
was removed and an arrangement represented in Fig. 11 was found. 
At this point it is well to recall that the fibres marked CS, in both 
Figs. 10 and 11 are those fibres of the inner circular muscular coat 
which lie immediately in front of and also under the ampulla. These 
muscle fibres, Fig. 11 CS, run under the ampulla and there decussate 
irregularly, so that the fibres of the one side pass to the other side 
and then curving upward and backward around the common bile-duct, 
embrace it. Here is seen the origin or termination of those muscle 
fibres which embrace the common bile-duct and bend forward as they 
pass under the bile-duct. Passing from this place of decussation, 
back toward the point of entrance of the common bile-duct into the 
intestinal wall, one finds the continuation of those muscle fibres which 
simply embrace the duct without bending forward as they pass under 
it, Eig: 11. LR. 
The muscle fibres of the outer longitudinal muscular coat, which 
lie in front of the ampulla and under the fibres, CS, have no con- 
nexion with the muscular arrangement of the duodenal portion of the 
common bile-duct. Further back, however, near the decussation of 
the fibres, CS, the fibres of the outer longitudinal muscle coat seem 
to be more or less involved in the general decussation. Some of the 
fibres of the outer longitudinal muscle coat run up to the side of the 
bile-duct, then bend around and run forward on it and at its side 
toward the ampulla. Others, when they reach the side of the duct, 
plunge inward and mingle with those bundles which embrace the 
common bile-duct. Serial cross-sections of the duodenal portion of 
the common bile-duct of the rabbit also give complete confirmation 
of the anatomy of the sphincter muscle just described. 
The Sphincter of the Common Bile-duct in Man. 
Preliminary to the description of the duodenal portion of the 
human common bile-duct, it will be well to state that many individual 
variations in structure occur but that these variations do not alter 
the general anatomical bearing of the region. Fig. 12 shows the 
entrance of the common bile-duct, B, and the duct of Wırsung, W, 
into the intestinal wall. We see a simple separation of the fibres of 
the outer longitudinal muscular coat of the intestine, ZI. The com- 
mon bile-duct and the duct of Wirsuna@ pass through this separation. 
At F we find muscle fibres arising from the outer longitudinal mus- 
cular coat. These fibres run up on the common bile-duct and 
Anat. Anz. XVII. Aufsätze, 14 
