Journal of Animal Research & Veterinary Science Category: Agriculture Type: Research Article
Anatomical Study on the Pelvic Diaphragm of Male Balady Dog
- Mohammed A Nazih1*
- 1 Lecturer Of Anatomy And Embryology, Faculty Of Veterinary Medicine, New Valley University, New Valley Governorate, Egypt
*Corresponding Author:Mohammed A Nazih
Lecturer Of Anatomy And Embryology, Faculty Of Veterinary Medicine, New Valley University, New Valley Governorate, Egypt
Tel: +20 1003732616,
Received Date: Jun 24, 2019 Accepted Date: Jul 18, 2019 Published Date: Jul 25, 2019
MATERIAL AND METHODS
The red dotted lines for ischiorectal fossae and the bluish one for the urogenital triangle.
For examining the urogenital triangle, a median longitudinal incision was cut along the scrotum and prepuce to the level of the pubic symphysis. All dimensions were measured using varineir caliper.
It is interesting to note that, there was a thick fatty coat covered the areas of dissection, so carful dissection is preferred.
The intermediate perineal part represents the perineal body and the longitudinal cutaneous perineal muscle and the ventral one is composed of the urogenital diaphragm. The perineal fasciae represent the latter and is composed of superficial and deep parts.
The dorsal part
Figure 3a: A photograph the perineal region (lateral view).
Figure 3b: A photograph showing the ischiorectal fossa (Caudolateral view).
1- Sacroischiatic ligament
2- Lateral coccygeus muscle
3- Pubococcygeus muscle
4- Ischiococcygeus muscle
5- External sphincter ani muscle
6- Internal obturator muscle
The dotted triangular region indicates the right ischiorectal fossa
1- Lateral coccygeus muscle (reflected)
2- Pubococcygeus muscle
3- Ischiococcygeus muscle
4- External phincter ani muscle
2- External phincter ani M
3- Ischial tuberosity
4- Colle’s fascia
5- Penie part of retractor penis M
6- Superficial perineal pouch
Figure 6: A photograph showing the perineal region (caudal view).
1- Lateral coccygeus M
2- External sphincter ani M
3- Ischial tuberosity
4- Colle’s fascia
5- Penile part of retractor penis M
6- Ischiocavernosus M
7- Bulbospongiosus M
8- Scrotal septum
9- Deep penile fascia
10- Superficial penile fascia
1- External sphinter ani M
2- Ishiococcygeus M
3- Pubococcygeus M
4- Lateral coccygeus M
5- Ischiocavernosus M
6- Bulbospongiosus M
7- Penile part of retractor penis M
8- Perineal M
9- Pelvic urethra
10- Deep (dorsal) layer of the deep perineal fascia
11- Ischial tuberosity
12- Internal obturator M
The black arrow indicates the ischiourethralis M (covered by 10)
The blue arrow indicates superficial perineal fascia (septum between 5 and 6)
Figure 8: A photograph showing the perineal region (removed left half of pelvic bone).
1- Iliococcygeus M
2- Pubococcygeus M
3- Ischiococcygeus M
4- Vertebral part of retractor penis M
5- External sphincter ani M
6- Perineal M
7- Bulbospongiosus M
8- Left penile crus
Figure 9: A photograph showing the perineal region (left lateral view).
1- External sphinter ani M
2- Perineal M
3- Perineal body
4- Ischiococcygeus M
5- Pubococcygeus M
The anal part (Suspensory apparatus of the anus), includes the rectococcygeus and the retractor penis muscle. The former, (Figures 10 and 11a) is the extrarectal continuation of the rectal musculature to the coccygeal vertebrae. The median dorsal longitudinal rectal muscle fibers coalles at the level of the pelvic out let to form a caudo dorsal projection inserted in the ventral aspect of the 5th caudal vertebra.
Figure 10: A photograph showing the perineal region (deep dissection).
1- Retractor penis M
2- Rectum (cut)
3- Pelvic urethra
5- Urinary bladder
6- Ischiococcygeus M
7- Pubococcygeus M
8- Iliococcygeus M
9- Ventral sacrococcygeus M
10- Left penile crus the yellow arrow indicates the obturator nerve
11- Rectococcygeus M
1- Medial coccygeus group (reflected)
2- Rectococcygeus M
3- Vertebral part of retractor penis M
4- External sphincter ani M
5- Perineal M
6- Perineal body
7- Bulbospongiosus M
The black arrow indicates the retractor penis M
The blue arrow indicates the rectal part
The green arrow indicates the penile part
The red arrow indicates the anal part of retractor penis M
The Retractor penis muscle (Figures 5,6,10,11a,11b,12), it consists of two parts; large and vertebral, the former is represented in right and left thin flat tape like in shape bundles. Each arises from the ventral aspect of the 1st and 2nd caudal vertebrae. It is directed in a caudoventral direction to run on the dorsolateral aspect of the anorectal junction. At the level of the dorsal insertion of the medial coccygeal muscle group, it inclines laterally on the anal canal. It passes on the deep face of the ischiococcygeus muscle, where the muscle divides into strong anal, penile and rectal parts. The former, is the caudal one and extends along the dorsolateral side of the anal passage, it proceeds deeply to the para-anal sinus, where the bundles terminate between the anal sphincter muscles. The penile part is the longest and crosses the lateral side of the anal canal in a vertical direction. It reaches the ventral border of the latter, where both fibers of the opposite sides are collected commonly in a single bundle and pass caudally between both perineal muscles. The muscle extends along the ventral border of penis to the glans and enrolled in the deep penile fascia. The rectal division is the cranial smaller part and its fibers are encircled with that of the terminal part of the rectum.
Figures 12: A photograph showing the penile region, deep dissection (lateral view).
1- Deep penile fascia
2- superficial penile fascia
3- Retractor penis M
4- Ischiocavernosus M
The vertebral part (Figures 8,11a,11b), is a thin flat fascicles derive from the ventral aspect of the 3rdcaudal vertebra. The muscle passes ventrally and vertically on the caudal aspect of the external sphincter ani muscle and deeply to the ischiococcygeus muscle. The muscle fibers of both sides terminate in the bulb of penis.
The intermediate part
The perineal muscle (Figures 8,9,11a,7) is the right and left ventral median longitudinal continuation of the external sphincter ani muscle. Each short bundle ascends from the perineal body on the lateral aspects of the penile part of retractor penis muscle. The muscle bundles encircle both sides of the anal canal respectively and joined together forming the external anal sphincter.
The ventral part
The perineal fat coat covers the ischiorectal fossae and the area of urogenital triangle, where over the former, the fat bad supports the muscles of the dorsal part of the pelvic diaphragm caudally and laterally. While on the urogenital triangle, the coat divides it from the skin externally figure 2.
The membranous layer (Colle’s fascia), (Figures 5,6,13,14) is a fibrous sheath extending from the perineal body dorsally and bilaterally stretched to the ischial tuberisities. It covers the caudoventral aspect of the ischial arch and extends ventrally to envelope the root of penis. At the arch, it coats the bulbospongiosus muscle and wraps around the penile part of retractor penis muscle. A fibrous division arises to separate between the bulbospongiosus and ischiocavernosus muscle. The fascia continues around the intrascrotal part of penis, where it receives the scrotal septum at the median plane. It proceeds cranially to join the tunica dartus of penis (superficial penile fascia) and the dorsal aspect of the latter, attached to the suspensory ligament of penis. Cranially, the dorsal extension of the superficial penile fascia, continued with the scrapa fascia of the abdominal wall. Colle’s fascia encloses a space or pouch (superficial perineal pouch) divides the deep penile fascia (internally) and perineal fat (externally). It contains the blubospongiosus and ischiocavernosus muscle.
2- Deep penile fascia
3- Superficial penile fascia
The dotted line indicates the junction between the superficial penile fascia and scrapa
Figures 14: A diagram showing the line of extension of colle’s fascia.
The yellow lines indicates the colle’s fascia (superficial perineal fascia)
The blue line indicates the superficial penile fascia
The red line indicates the scrapa fascia of the abdominal wall
The green line indicates the perineal membrane
The brown line indicates the dorsal layer of the urogenital diaphragm
In general concern, the pelvic diaphragm was integrated in three distinct regions; dorsal, intermediate and ventral. The former, represented the ischiorectal part which lodged in the anal triangle. Nearly achieved findings were mentioned by Budras et al.  in dog which described the ischiorectal fossa without the anal triangle. While the recent results revealed that the right and left ischiorectal fossae comprised the anal triangle. On the other hand, the intermediate perineal region connected the dorsal to the ventral one. The latter, included in the urogenital triangle and comprised the urogenital diaphragm, while the intermediate one included the perineal body and muscle. A classification which wasn’t reported in the previous available literatures. Budras et al.,  in dog had a different classification in which they added three parts of pelvic diaphragm to the coccygeus and levator ani muscle. The authors categorized the parts into anal, perineum proper, and urogenital. The former consisted of external and internal anal muscles and rectococcygeus muscle. The proper division included the perineal body and muscle. While the urogenital one was composed of ischiocavernosus, bulbospongiosus and retractor penis muscle. In this aspect, Sisson and Grossman  in domestic animals, Bllenger and Canfield  in dog had the opinion that the pelvic diaphragm was consisted of coccygeus and levator ani muscle. The latter authors added the superficial gluteal, internal obturator, external anal sphincter muscle and sacrotuberous ligament.
It was important to note that the ischiorectal part of the pelvic diaphragm of the current study, included the coccygeus muscle group and an anal part (suspensory apparatus of anus). The former, represented the lateral coccygeus muscle and medial coccygeus group (levator ani muscle). A nearly findings were cited by Desai  and Miller et al.  in dog which reported lateral and medial coccygeus muscle and did not grouped the latter. Evans and delahunta  and Budras et al.,  in dog mentioned coccygeus and levator ani muscle. While Sisson and Grossman  in domestic animals had the opinion that there were coccygeus and retractor ani muscle. The lateral coccygeus muscle of balady dog was described as quadrilateral in shape, arose from the ischiatic spine and had cranial, caudal, ventral and dorsal borders. Nearly recorded results were cited by Desai  and Miller et al.,  in dog but they weren’t described its borders and the muscle was attached to the coccygeal vertebrae. However, the present study reported that the muscle was inserted to the lateral aspect of the first three caudal vertebrae. In this aspect, Budras et al.,  in dog declared that the coccygeus muscle was attached to the first four caudal vertebrae. While Hall et al.,  in dog cited that it was inserted to the first caudal vertebra.
Concerning the anatomical structures of the medial coccygeus group (levator ani muscle) in the study at hand revealed that the levator ani muscle was grouped into three muscular divisions of thin flat fascicles; Iliococcygeus, pubococcygeus and ischiococcygeus muscle. The former was the cranial and the pubococcygeus was the middle largest while the last was the caudal and smaller one. Nearly findings were cited by Koing and Liebich  in domestic mammals which declared that the levator ani muscle represented the iliocaudalis and ischiocaudalis muscle. On the other hand, Hall et al.,  in dog have the opinion that there were three divisions of the levator ani muscle; pubococcygeus, iliococcygeus and puborectalis. Each part of the levator ani muscle in the balady dog had a distinct area of origin, the iliococcygeus muscle arose from the cranial border of the ilio-pubic junction and the obturator nerve separated it from the pubococcygeus muscle. The present study described the pubococcygeus muscle as the main muscle of the medial coccygeus group with fan shaped fascicles. The muscle originated from dorsal and lateral aspects of the pelvic symphysis and pubis. It was attached dorsally to the anal canal to the 4th caudal vertebra and related medially to a thick fat bad separated it from the prostate gland. A result which confermed the suggestion of Hedlund , Bllenger and Canfield , Ferreira and Delgado , Ribeiro  and Souza et al.,  which confirmed the relation between the prostatic hyperplasia and the incidence of perineal hernia, where the hypertrophid gland will damaged the fibers of the levator ani muscle. The ischiococcygeus part of the levator ani muscle was attached from the caudo dorsal aspect of the ischial part of pelvic symphysis. In this regard, most of the available literatures, Desai  and Miller et al.,  in dog, Sisson and Grossman  in domestic animals and Evans and delahunta  and Budras et al.,  in dog had the opinion that the muscle was a single, not grouped and originated from the medial edge of ilium and dorsal aspect of the pubic symphysis. Sisson and Grossman, added that the muscle originated from the ischiatic spine and sacroischiatic ligament. The recently applied study revealed that all parts of the levator ani muscle were inserted to the 4th caudal vertebra. A little differences were recorded by Desai  and Miller et al.,  in dog which determined that the muscle was inserted to the 3rd to 6th caudal vertebrae. While Budras et al.,  in dog recorded its insertion to the 4th to 7th caudal vertebrae. The name levator ani muscle was referred to the human anatomy, as the normal attitude of the human body allowed the muscle to elevate the anus upward. Regarding that in animals, their normal body posture will changed the name to the retractor ani muscle as considered by Sisson and Grossman  in domestic animals. In this aspect, Drake et al.,  in human declared that the muscle consisted of the ischiococcygeus, pubococcygeus and puborectalis. And the latter surrounded the anal opening and supported it during defecation. That was in agreement with the opinion of Hall et al.,  in dog. While in contrary to our dissecting observation, where the parts of the medial coccygeus group were inserted to the caudal vertebrae without reinforcement fibers to the sphincter anal muscle. The ischiococcygeus muscle was separated from the external anal phincter by the vertebral head of retractor penis muscle. In this regard, the medial coccygeus muscle group of both sides formed the levator window, which allowed the anal canal to pass through freely with its suspensory apparatus. Where the study used the name medial coccygeus group rather than the levator ani one. Similarly cited results were recorded by Budras et al.,  in dog which affirmed very few muscle fibers derived from the levator ani muscle to the external anal sphincter and the name levator ani was misleading. A results which were in contrast to that of Desai  and Miller et al.,  in dog, Sisson and Grossman  in domestic animals which revealed that the levator ani muscle bended with the external anal sphincter. Ischiococcygeus muscle in the present dissection and that of Koing and Liebich  in dog was a homologous to that considered puborectalis by Drake et al.,  in human and Hall et al.,  in dog.
Regarding the perineal muscle in the present work, the muscle extended from the perineal body and encircled the lateral sides of the anal canal formed the external anal sphincter. Nearly results were cited by Budras et al.,  in dog which revealed that the muscle extended from the external anal sphincter to the bulbospongiosus muscle. That was different from the opinion of Hall et al.,  which mentioned that the anal sphincter muscle originated from the anococcygeal ligament and coursed ventrally on both sides of the external anal opening.
Our dissection revealed that the perineal body was a fibrous mass ventrally located to the anal opening where it gave an attachment for the perineal muscle and fasciae. That was different from that reported by Hall et al.,  in dog which declared that there were no muscle fibers attached to the perineal body.
The study described the suspensory apparatus of anus and decleared that the retractor penis muscle consisted of four divisions; anal, penile, rectal and vertebral. The former was the broadest, the penile was the longest, the rectal was the smallest and all derived from a common bundle. While the vertebral division descended from the 3rd caudal vertebra. Nearly similar findings were reported by Budras et al.,  in dog. In this regard, Evans and delahunta  named three parts of the muscle; pars analis, rectalis and penile.
The ventral part of the pelvic diaphragm was recently described, where it comprised the urogenital diaphragm. The latter was composed of dorsal and ventral layers which were considered the deep perineal fascia. Its dorsal layer extended from the pelvic symphysis to the level of ischial arch, where it twirled ventrally to form the ventral layer. A very small deep perineal pouch was formed between them enclosed the ischiourethralis muscle. In case of human, Drake et al.,  recorded the external urethra muscle was wrapped in the urogenital diaphragm. The ventral layer of the urogenital diaphragm was the perineal membrane which attached cranially to the pubic symphysis. At the ischial arch, it formed the superficial perineal fascia (Colle’s fascia). A result which wasn’t cited in the available respected literatures. The Colle’s fascia covered the superficial perineal pouch which contains the bulbospongiosus and ischiocavernosus muscle. That was similar to findings that reported by Drake et al.,  in human.
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Citation:Nazih MA (2019) Anatomical Study on the Pelvic Diaphragm of Male Balady Dog. J Anim Res Vet Sci 3: 019.
Copyright: © 2019 Mohammed A Nazih, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.