A missing distal complex of the external and internal anal sphincters: a macroscopic and histologic study using Japanese and German elderly cadavers.
Surg Radiol Anat
; 43(5): 775-784, 2021 May.
Article
em En
| MEDLINE
| ID: mdl-33135107
ABSTRACT
The lower margin of the internal anal sphincter (IAS) is considered to lie on a J-shaped, subcutaneous part (SCP) of the external anal sphincter (EAS). The lower IAS is united with the J-shaped SCP to form a smooth-striated muscle complex. In the first part of this study, we ensured the presence of the J-shaped EAS in the lateral wall of the anal canal from 12 near-term fetuses. Second, in the lateral anal wall, the examination of the longitudinal section from 20 male and 24 female Japanese cadavers (72-95 years-old) demonstrated that the J-shaped EAS was lost in 15 (34%) due to the very small SCP. Third, we demonstrated that the J-shaped EAS was restricted in the latera anal wall using longitudinal histological sections of the anal canal from 11 male Japanese cadavers (75-89 years-old). Therefore, a site-dependent difference in the IAS-EAS configuration was evident. Finally, we compared a frequency of the lost J-shape between human populations using 10 mm-thick frontal slices from 36 Japanese and 28 German cadavers. The two groups of cadavers were compatible in age (a 0.2-years' difference in males). The macroscopic observations revealed that the J-shaped EAS was absent from 13 (36%) Japanese and six (20%) German specimens, suggesting that the SCP degeneration occurred more frequent in elderly Japanese than elderly German individuals (p < 0.05). The distal IAS-EAS complex seemed to push residual feces out of the anal canal at a transient phase from evacuation to closure. The absence might be the first sigh of anal dysfunction.
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Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Canal Anal
/
Músculo Esquelético
/
Músculo Liso
Limite:
Aged
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Aged80
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Female
/
Humans
/
Male
País/Região como assunto:
Asia
/
Europa
Idioma:
En
Revista:
Surg Radiol Anat
Assunto da revista:
ANATOMIA
/
RADIOLOGIA
Ano de publicação:
2021
Tipo de documento:
Article
País de afiliação:
Japão