Levator ani muscle

In this study, where possible, anabolic activity is expressed as the ratio of the activity of the compound to that of testosterone or testosterone propionate (in most cases subcutaneous administration of the drug) or methyltestosterone (in most cases oral administration of the drug) in increasing the weight of the levator ani muscle of the rat. The standard of comparison (T = testosterone, TP = testosterone propionate, MT = methyltestosterone) is expressed as 100% activity. Androgenic activity where possible, is expressed as the ratio of the activity of the compound compared to that of testosterone or testosterone propionate (subcutaneous administration) or methyltestosterone (oral administration) in increasing the weight of the seminal vesicles or ventral prostate of the rat. 

The anaboliciandrogenic ratio (quotient), Q, is expressed as the anabolic activity of the compound compared to T, TP, or MT as measured by the percent increase in weight of the levator ani muscle in the castrated... 

Hershberger, L.G., Shipley, E.G. and Meyer, R.K. (1953) Myotrophic activity of 19-nortestosterone and other steroids determined by modified levator ani muscle method. Proceedings of the Society for Experimental Biology and Medicine, 83, 175-180. 

The levator ani muscle generally requires another logarithmic increase in dose before definitely responding. This extremely useful assay is adaptable for comparison of materials, whether given parenterally or orally (37). 

The laboratory mouse can also be used for this purpose, except that its prostate is extremely small and comparatively large doses must be used for response, whereas, in contrast to the rat, its seminal vesicle appears to be somewhat more sensitive and is more generally employed as an androgenic end point. Here the weight of the kidney rather than the levator ani muscle is an index of anabolic activity (27). 

Male rats 23-25 days of age are castrated. Three weeks later the test compounds dissolved in corn oil are administered intramuscularly daily for seven days. One day after the test injection the animals are sacrificed and the seminal vesicles, ventral prostates and levator ani muscles removed and weighed. Comparison with data obtained from untreated controls permits evaluation of androgenic effect (seminal vesicles and ventral prostates) and anabolic effect (levator ani). 

The levator ani muscle responds to some extent to androgens per se. Nitrogen retention studies are therefore preferred as a more valid index for anabolic activity. 

The Wingspread classification divides anorectal malformations into high, intermediate or low form (Stephens and Smith 1988). The classification is based on the level of the rectal pouch relative to the levator ani muscle, i.e. above the levator ani is designated a supralevator or high, at the level of the... 

The borders of the posterior compartment are the skeletal elements of the sacrum and the coccyx dorsally. They are completed by the anococcygeal body (see Table 1.1) dorsocaudally and by the components of the levator ani muscle laterally and cau-dally (Fig. 1.1a). The rectovaginal fascia constitutes an incomplete border ventrocranially The ventro-... 

The borders of the anterior compartment are the pubic symphysis ventrally the components of the levator ani muscle laterally (Fig. 1.1b) and the perineal membrane (see Table 1.1) caudally. There is no distinct border between the anterior and middle compartment in the female. The contents of the anterior compartment are bladder and urethra (Fig. 1.1b). 

The borders are the components of the levator ani muscle laterally and the perineal body caudally (Fig. 1.1b). No distinct borders can be described ventrally, whereas the rectovaginal fascia/septum constitutes the dorsal border. The middle compartment contains the female genital organs that are arranged in a more or less coronal plane. In more detail the ovaries, the uterine tubes, the uterus and the vagina are situated in this compartment (Fig. 1.1a). 

Fig. 1.5a-c. Levator ani muscle (arrows), a Axial section (5 mm) of an adult female. xO.6. b Parasagittal MR image of an adult female, c Sagittal section (5 mm) of an adult female, x 1.0. jsc, ischiococ-cygeal muscle if, ischioanal fossa ilc, iliococcygeal muscle pc, pubococcygeal muscle... 

Within the posterior pelvic compartment all components of the levator ani muscle are to he found the puhococcygeus muscles and the iliococcygeus muscles constitute an irregular plate and insert into the coccyx where they overlap each other in a staggered arrangement (Fig. 1.5). The inferior component, the puhorectalis muscles, do not insert into any skeletal... 

Within the anterior compartment two structures are found that are composed of dense connective tissue the tendinous arch of the pelvic fascia that originates from the pubic bone and that is connected to the pelvic parietal fascia covering the levator ani muscle on its visceral side (superior fascia of the pelvic diaphragm see Table 1.1) and the semicircular fibrous sheath that covers the ventral and lateral... 

Fig. l.lOa-d. Anterior compartment and the so-called ligaments of the urethra.a Axial section (400 pm) of a 24-week-old female fetus with the semicircular urethral sheath arrows). xl2. b Sagittal section (500 pm) of a 13- to 14-week-old female fetus with the pubovesical ligament white spots) and the origin of the tendinous arch arrowhead). x25. c Axial section (400 pm) of a 17-week-old female fetus with the pubovesical ligaments white spots), x 12. d Axial section (5 mm) of an adult female with the pubovesical ligaments white spots). x7.5. pbo, pubic bone u, urethra lam, levator ani muscle... 

The striated muscles of the anterior compartment are the ventral parts of the levator ani muscle (see Table 1.1), i.e. the pubococcygeus and puborectalis muscle of each side. As they are covered by the superior fascia of the pelvic diaphragm, they are clearly separated by the adjacent organs (Fig. 1.10a,d and... 

The middle compartment does not have any specific striated muscles. The lateral vaginal wall comes in close contact to the puborectalis portion of the levator ani muscle. Both structures are always separated by the superior fascia of this muscle (Fig. 1.6b). 

The intralevatoric side of the perineal body is connected with connective tissue septa of the ischioanal fossa [11] that are also connected to the inferior fascia of the levator ani muscle [30]. 

Fritsch H, Frohlich B (1994) Development of the levator ani muscle in human fetuses. Early Hum Dev 37 15-25... 

Fig. 12.13. Vaginal metastasis of malignant melanoma. Contrast enhanced CT. An unspecific mass with inhomogeneous contrast enhancement in the vagina is shown. The right levator ani muscle (arrow) can not be well delineated suggesting tumor involvement. (Figure courtesy of Dr. Forstner)...

Due to the lack of whole coverage of the pelvic floor coronal images are necessary to evaluate the entire anatomic region [12, 34, 42, 43]. We perform a coronal stack of slices while the patient is continuously straining. Those images depict the levator ani muscle in more detail and facilitate the detection of... 

In a normal anatomical setting the vagina, the rectum and the posterior components of the levator ani muscle lie one upon the other (Fig. 13.1a). Therefore, the position of the vagina and uterus is dependent on the amount of filling of the rectal ampulla. 

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