PURPOSE: It is still unclear whether the longitudinal anal muscles or conjoint longitudinal coats (CLCs) are attached to the vagina, although such an attachment, if present, would appear to make an important contribution to the integrated supportive system of the female pelvic floor. MATERIALS AND METHODS: Using immunohistochemistry for smooth muscle actin, we examined semiserial frontal sections of 1) eleven female late-stage fetuses at 28-37 weeks of gestation, 2) two female middle-stage fetus (2 specimens at 13 weeks), and, 3) six male fetuses at 12 and 37 weeks as a comparison of the morphology. RESULTS: In late-stage female fetuses, the CLCs consistently (11/11) extended into the subcutaneous tissue along the vaginal vestibule on the anterior side of the external anal sphincter. Lateral to the CLCs, the external anal sphincter also extended anteriorly toward the vaginal side walls. The anterior part of the CLCs originated from the perimysium of the levator ani muscle without any contribution of the rectal longitudinal muscle layer. However, in 2 female middle-stage fetuses, smooth muscles along the vestibulum extended superiorly toward the levetor ani sling. In male fetuses, the CLCs were separated from another subcutaneous smooth muscle along the scrotal raphe (posterior parts of the dartos layer) by fatty tissue. CONCLUSION: In terms of topographical anatomy, the female anterior CLCs are likely to correspond to the lateral extension of the perineal body (a bulky subcutaneous smooth muscle mass present in adult women), supporting the vaginal vestibule by transmission of force from the levator ani.
Anal Canal/*anatomy & histology/embryology ; Female ; Fetus/anatomy & histology ; Humans ; Male ; Muscle, Smooth/*anatomy & histology/embryology ; Pelvic Floor/anatomy & histology ; Sex Characteristics ; Vagina/*anatomy & histology/embryology

Objective: To document the anatomical structure of the area anterior to the anorectum passing through the levator hiatus between the levator ani slings bilaterally. Methods: Three male hemipelvises were examined at the Laboratory of Clinical Applied Anatomy, Fujian Medical University. (1) The anatomical assessment was performed in three ways; namely, by abdominal followed by perineal dissection, by examining serial cross-sections, and by examining median sagittal sections. (2) The series was stained with hematoxylin and eosin to enable identification of nerves, vessels, and smooth and striated muscles. Results: (1) It was found that the rectourethralis muscle is closest to the deep transverse perineal muscle where the longitudinal muscle of the rectum extends into the posteroinferior area of the membranous urethra. The communicating branches of the neurovascular bundle (NVB) were identified at the posterior edge of the rectourethralis muscle on both sides. The rectum was found to be fixed to the membranous urethra through the rectourethral muscle, contributing to the anorectal angle of the anterior rectal wall. (2) Serial cross-sections from the anal to the oral side were examined. At the level of the external anal sphincter, the longitudinal muscle of the rectum was found to extend caudally and divide into two muscle bundles on the oral side of the external anal sphincter. One of these muscle bundles angled dorsally and caudally, forming the conjoined longitudinal muscle, which was found to insert into the intersphincteric space (between the internal and external anal sphincters). The other muscle bundle angled ventrally and caudally, filling the gap between the external anal sphincter and the bulbocavernosus muscle, forming the perineal body. At the level of the superficial transverse perineal muscle, this small muscle bundle headed laterally and intertwined with the longitudinal muscle in the region of the perineal body. At the level of the rectourethralis and deep transverse perineal muscle, the external urethral sphincter was found to occupy an almost completely circular space along the membranous part of the urethra. The dorsal part of the external urethral sphincter was found to be thin at the point of attachment of the rectourethralis muscle, the ventral part of the longitudinal muscle of the rectum. We identified a venous plexus from the NVB located close to the oral and ventral side of the deep transverse perineal muscle. Many vascular branches from the NVB were found to be penetrating the longitudinal muscle and the ventral part of rectourethralis muscle at the level of the apex of the prostate. The rectourethral muscle was wrapped ventrally around the membranous urethra and apex of the prostate. The boundary between the longitudinal muscle and prostate gradually became more distinct, being located at the anterior end of the transabdominal dissection plane. (3) Histological examination showed that the dorsal part of the external urethral sphincter (striated muscle) is thin adjacent to the striated muscle fibers from the deep transverse perineal muscle and the NVB dorsally and close by. The rectourethral muscle was found to fill the space created by the internal anal sphincter, deep transverse perineal muscle, and both levator ani muscles. Many tortuous vessels and tiny nerve fibers from the NVB were identified penetrating the muscle fibers of the deep transverse perineal and rectourethral muscles. The structure of the superficial transverse perineal muscle was typical of striated muscle. These findings were reconstructed three-dimensionally. Conclusions: In intersphincteric resection or abdominoperineal resection for very low rectal cancer, the anterior dissection plane behind Denonvilliers' fascia disappears at the level of the apex of the prostate. The prostate and both NVBs should be used as landmarks during transanal dissection of the non-surgical plane. The rectourethralis muscle should be divided near the rectum side unless tumor involvement is suspected. The superficial and deep transverse perineal muscles, as well as their supplied vessels and nerve fibers from the NVB. In addition, the cutting direction should be adjusted according to the anorectal angle to minimize urethral injury.
Humans ; Male ; Rectum/surgery* ; Anal Canal/anatomy & histology* ; Rectal Neoplasms/surgery* ; Proctectomy ; Urethra/surgery*

PURPOSE: We recently demonstrated the morphology of the anococcygeal ligament. As the anococcygeal ligament and raphe are often confused, the concept of the anococcygeal raphe needs to be re-examined from the perspective of fetal development, as well as in terms of adult morphology. MATERIALS AND METHODS: We examined the horizontal sections of 15 fetuses as well as adult histology. From cadavers, we obtained an almost cubic tissue mass containing the dorsal wall of the anorectum, the coccyx and the covering skin. Most sections were stained with hematoxylin and eosin or Masson-trichrome solution. RESULTS: The adult ligament contained both smooth and striated muscle fibers. A similar band-like structure was seen in fetuses, containing: 1) smooth muscle fibers originating from the longitudinal muscle coat of the anal canal and 2) striated muscle fibers from the external anal sphincter (EAS). However, in fetuses, the levator ani muscle did not attach to either the band or the coccyx. Along and around the anococcygeal ligament, we did not find any aponeurotic tissue with transversely oriented fibers connecting bilateral levator ani slings. Instead, in adults, a fibrous tissue mass was located at a gap between bilateral levator ani slings; this site corresponded to the dorsal side of the ligament and the EAS in the immediately deep side of the natal skin cleft. CONCLUSION: We hypothesize that a classically described raphe corresponds to the specific subcutaneous tissue on the superficial or dorsal side of the anococcygeal ligament.
Aged, 80 and over ; Anal Canal/*anatomy & histology/embryology ; *Cadaver ; Female ; *Fetus ; Humans ; Male ; Muscle, Smooth/*anatomy & histology/embryology ; Rectum/*anatomy & histology/embryology

BACKGROUNDManometric pressure asymmetry of the anal sphincter exists in the anal canal. There are reports about the anatomy of the anal sphincter, but the relationship between the configuration and the pressure asymmetry of the anal sphincter is not clear. This study is to investigate the anatomic evidence and clinical application of anal sphincter pressure asymmetry.

METHODSPC polygram HR at the state of relaxing and squeezing was used in 27 normal children and 12 abnormal ones with fecal incontinence.

RESULTSIn normal children, longitudinal pressure gradients existed at eight channels in the anal canal, and the maximal pressure 1 cm from the anal verge. Longitudinal pressure asymmetry changes of eight channels also existed in the anal canal, from 3 cm to 2 cm to 1 cm from the anal verge. The high pressure distribution changed from the posterior to the anterior anal canal. Anteriorly, 1 cm from the anal verge, the maximal pressure was formed in the anal canal. However, neither longitudinal pressure gradients nor longitudinal pressure asymmetry changes were seen in patients with fecal incontinence.

CONCLUSIONThe configuration and function of the striated muscle complex possibly contribute to the formation of the pressure asymmetry of the anal sphincter, which is essential to anal control.

Adolescent ; Adult ; Anal Canal ; anatomy & histology ; physiology ; Child ; Child, Preschool ; Fecal Incontinence ; physiopathology ; Female ; Humans ; Male ; Manometry ; Pressure

The primary importance of magnetic resonance (MR) imaging in evaluating anal fistulas lies in its ability to demonstrate hidden areas of sepsis and secondary extensions in patients with fistula in ano. MR imaging is relatively expensive, so there are many healthcare systems worldwide where access to MR imaging remains restricted. Until recently, computed tomography (CT) has played a limited role in imaging fistula in ano, largely owing to its poor resolution of soft tissue. In this article, the different imaging features of the CT and MRI are compared to demonstrate the relative accuracy of CT fistulography for the preoperative assessment of fistula in ano. CT fistulography and MR imaging have their own advantages for preoperative evaluation of perianal fistula, and can be applied to complement one another when necessary.
Adult ; Anal Canal/anatomy & histology ; Female ; Humans ; *Magnetic Resonance Imaging ; Male ; Middle Aged ; Rectal Fistula/diagnosis/*radiography/surgery ; Tomography, X-Ray Computed ; Young Adult

A perianal tick and the surrounding skin were surgically excised from a 73-year-old man residing in a southwestern costal area of the Korean Peninsula. Microscopically a deep penetrating lesion was formed beneath the attachment site. Dense and mixed inflammatory cell infiltrations occurred in the dermis and subcutaneous tissues around the feeding lesion. Amorphous eosinophilic cement was abundant in the center of the lesion. The tick had Y-shaped anal groove, long mouthparts, ornate scutum, comma-shaped spiracular plate, distinct eyes, and fastoons. It was morphologically identified as a fully engorged female Amblyomma testudinarium. This is the third human case of Amblyomma tick infection in Korea.
Aged ; Anal Canal/*injuries/parasitology/*pathology/surgery ; Animals ; Female ; Histocytochemistry ; Humans ; Ixodidae/anatomy & histology/*growth & development ; Korea ; Male ; Microscopy ; Skin/parasitology/pathology ; Tick Bites/*diagnosis/*pathology/surgery ; Tick Infestations/*diagnosis/*pathology/surgery