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Dissection of male pelvis from a lateral approach

Sphincter ani externus, close-up lateral view

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Image #169-3
Bassett ImageDiagram Image
Legend Image
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)