Dissection of male pelvis from a lateral approach

Sphincter ani externus, close-up lateral view

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Image #169-3

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)