Rectum
5
Plate371
RectumandAnalCanal
Sigmoid colon
Peritoneal reflection
Rectosigmoid junction
Rectal fascia
Longitudinal muscle layer
Circular muscle layer
Muscularis mucosae
Levator ani muscle
Anorectal line
Anal columns (Morgagni’s)
Anal sinus
Pectinate (dentate) line
Internal rectal venous plexus
in submucous space
Deep part* of external
sphincter muscle
Conjoined longitudinal muscle
Internal sphincter muscle
Anal valve
Anal crypt
Superficial part* of external
sphincter muscle
Anal glands
Transverse fibrous septum
Muscularis mucosae of anal canal
Peri-anal space
Subcutaneous part* of external sphincter muscle
Corrugator cutis ani muscle
External rectal venous plexus in peri-anal space
Intersphincteric groove (anocutaneous line)
15–17 cm
11–13 cm
8–9 cm
5–6 cm
4–5 cm
2.5–3 cm
0.5–1 cm
Sweat glands and
hairs in perianal skin
Anal verge
Pecten
Anoderm
Anatomical
anal canal
Surgical anal canal
*Parts variable and often indistinct
Superior
Middle
Inferior
Transverse folds
of rectum (valves
of Houston)
