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Dissection of male pelvis from a lateral approach

Sphincter ani externus, close-up lateral view

Image #169-3

KEYWORDS: Muscles and tendons.

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Higher resolution images are available for a fee. Contact Drew Bourn, PhD, MLIS.

Dissection of male pelvis from a lateral approach

Sphincter ani externus, close-up lateral view

The divisions of the sphincter ani externus are not as distinct in this specimen as they are in the preparation shown in view 159-6. The relation of parts of the levator ani muscle to the sphincter ani externus is illustrated here and is also shown in 171-4 after the wall of the anal canal has been opened.

1 .	Iliococcygeus muscle
2 .	Pubococcygeus muscle
3 .	Puborectalis muscle (1-3 are parts of the levator ani muscle)
4 .	Superior fascia of urogenital diaphragm
5 .	Upper pointer: Internal pudendal artery (cutoff) Lower pointer: Pudendal nerve (cut off)
6 .	Urethra (opened)
7 .	Bulb of penis (dissected)
8 .	Bulbospongiosus muscle (cut along midline)
9 .	Coccyx (terminal segment)
10 .	Perineal branch of sacral nerve IV
11 .	Anococcygeal ligament
12 .	Branch of inferior rectal nerve (cut off)
13 .	Area of insertion of Levator ani muscle into wall of anal canal
14 .	Deep part
15 .	Superficial part
16 .	Subcutaneous part (14-16 refer to the external anal sphincter muscle)