128 1MUSCULAR SYSTElM. 



be traced as an entire lining to the muscles of the abdomen ; and 

 is, from the resistance it opposes (which is by no means in- 

 considerable), of essential service in sustaining the burden of the 

 dependent viscera, in effecting which it. reduces the demand for 

 muscular action. Though it is an opening (removed a short dis- 

 tance, inwardly, from the external ring), called the internal abdo- 

 minal ring. 



3.— ANAL REGION. 



Comprehends a pair of muscles, and a single one. 

 RETRACTOR ANT. — {Iscfiiu-analis.) 



Situation. — On the side of the rectum, near its termination. 



Figure. — Long, slender, cylindroid. 



Attachment. — Inferiorly and anteriorly, to the sacro-sciatic 

 ligament, and to the os innominatum, below and behind the ace- 

 tabulum ; superiorly and posteriorly, to the lateral parts of the 

 rectum, close to its termination. 



Relations. — Externally, with the sacro-sciatic ligament ; inter- 

 nally, with the sphincter ani. 



Direction. — Curving obliquely around the gut. 



Structure. — Its posterior attachment is aponeurotic : at the 

 mesian line, inferiorly, where it meets its fellow, it terminates in 

 a small flat tendon. 



Action. — To retract the anus; to withdraw it within the pelvis. 



SPHINCTER ANl. 



Situation. — Encircling the termination of the rectum. 



Figure. — Oval ; open in the middle. 



Attachment. — Superiorly, to the coccyx, whence it descends 

 in two divisions; these diverge to include the gut between them, 

 around which they proceed, and again meet and unite inferiorly. 



Relations. — Posteriorly with the skin ; internally, with the in- 

 testine ; anteriorly, with the retractor. 



Direction. — Circular. 



Structure.— Va.\e and fleshy : connected, superiorly, with a 

 broad tendinous expansion, which attaches it to the coccyx. 



Jction.—To close the anus, after the expulsion of the fseces, 

 and to retain it closed. 



4._MALE GENITAL REGION. 



c REM ASTER. — ( lUo-testicularis.) 



Continued from the faschia superficialis abdominis upon the 

 spermatic chord, and thence into the fibrous texture of the scro- 



