1. Pelvic Diaphragm :
It is formed of levator ani Ms.+ small coccygeus Ms. + their covering fascia.
It is incomplete anteriorly to allow passage of urethra in males /and urethra & vagina in female.
N.supply :perineal branch of S4 N. and perineal branch of pudendal N.

2. The pelvic diaphragm : divides the cavity of pelvis into main pelvic cavity above & perineum below.
The perineum is diamond shaped ,bounded anteriorly by symphysis pubis …posteriorly by coccyx … laterally by ischial tuberosities.
Anal triangle : it is the posterior division of perineum /bounded posteriorly by tip of coccyx… and on each side by ischial tuberosity & sacrotuberous lig. overlapped by lower border of gluteus maximus.

3. Contents of Anal triangle :
Anus.
Lower part of Anal canal.(upper part lies in pelvis)
Ano-coccygeal body (or raphe) :a fibrofatty mass that extends from anus to tip of coccyx.
Ischio-rectal fossa on each side.

4. Anus :
lies in midline.
The skin around anus and over ischio-rectal fossa on each side is supplied by inferior rectal N. (somatic).
Lymph vessles of the skin of anus drain into medial group of superficial inguinal L.N.

5. Anal Canal
It is about 1,5 in. long, descending from rectal ampulla to anus.
Posteriorly : anococcygeal body, which is a mass of fibrous tissue lying between anal canal & coccyx.
Laterally : fat-filled ischiorectal fossae.
Anteriorly : In male : perineal body, urogenital diaphragm, membranous part of urethra, and bulb of penis In female : perineal body, urogenital diaphragm, and lower part of vagina.

6. Structure of anal canal
Mucous membrane of upper ½ is derived from hindgut entoderm.
It is lined by columnar epithelium.
It is thrown into vertical folds-anal columns, which are joined together at their lower end by semilunar folds called anal valves.
Nerve supply : autonomic hypo-gastric plexus (as rectal mucosa), sensitive only to stretch.
Arterial supply : superior rectal artery –of inferior mesenteric/ sup.rectal v., a tributary of inf. Mesenteric and portal v.
Lymphatic drainage : along sup. Rectal artery to pararectal nodes, then to inferior mesenteric nodes.

7. Structure of anal canal
Mucous membrane of lower ½ is derived from ectoderm of proctodeum.
It is lined by stratified squamous epithelium, which gradually merges at anus with perianal epidermis.
No anal columns.
Nerve supply : somatic inferior rectal N., sensitive to pain, temperature, touch and pressure.
Arterial supply : inferior rectal artery –of internal pudendal /inf.rectal v., a tributary of int. pudendal v. and drains to internal iliac v. (systemic venous drainage)
Lymphatic drainage : to medial group of superficial inguinal ligament.

8. Structure of anal canal
Pectinate line: it is the line of joining between upper & lower halves of anal canal/ at the level of anal valves..
Muscle coat : as rectum- consists of outer longitudinal & inner circular layer of smooth muscle. The longitudinal muscle descends between the internal & external anal sphincters.
Anal sphincters :
1-Involuntary internal sphincter: is formed by thickening of smooth circular L.of muscular coat at upper end of anal canal Voluntary external sphincter: a-Subcutaneous part : surrounds the lower end of anal and has No bony attachment b-superficial part : attached to coccyx behind and the perineal body in front c-deep part : encircle upper end of anal canal and has no bony attachments.

9. Involuntary internal sphincter supplied by …by symp. Fs
Involuntary internal sphincter supplied by …by symp. Fs. .from inferior hypogastric plexus.
Voluntary external sphincter… by inferior rectal N. + perineal branch of S4 N.
Puborectalis muscle
It is fibres of the two levator ani muscles, forming a sling around the junction of rectum & anal canal.
It is attached in front to pubic bones.
At the junction of rectum & anal canal, the internal sphincter, deep part of external sphincter & puborectalis muscles form a ring called anorectal ring which can be felt on rectal examination.

10. Ischiorectal Fossa : Its base is the skin of perineum.
Its medial wall is levator ani & anal canal.
Its lateral wall is obturator internus, covered with pelvic fascia.
Contents :dense fat , pudendal nerve & int.pudendal vessels inside the pudendal canal on the lat.wall of the fossa , inf. Rectal N.& vessels cross fossa to reach anal canal.

11. Pudendal Nerve : Branch of sacral plexus.
It leaves pelvis through greater sciatic foramen , crossing back of sacrospinous ligament, and passes through lesser sciatic foramen to enter perinum.
It passes in the pudendal canal in ischiorectal fossa.

12. Branches of Pudendal Nerve :
Inf. rectal N… supplies ext.anal sph., m.m.of lower ½ of anal canal & perianal skin.
Perineal N… supplies muscles of urogenital triangle ,and skin of scrotum (or labia majora).
Dorsal N. of penis… to penis (or clitoris).

13. Internal Pudendal Vessels :
Internal pud.artery … branch of internal iliac artery ,passes from gluteal region to pelvis through G.S.foramen and enters perineum through lesser sciatic foramen.
Branches of int. pud.artery :1-inf. Rectal artery supplies… lower ½ of anal canal branches to penis (or labia majora & clitoris).
Int. pud. Vein : drains into int. iliac vein.

14. Internal Hemorroids (piles) :
Are due to varicosities of tributareis of superior rectal vein.
Hemorrhoid is a fold of m.m. & submucosa containing a varicosed tributary of sup. Rectal vein. (B)
It occurs in upper ½ of anal canal where m.m. innervated by autonomic N.S., so they are painless and sensitive only to strech.
Position of varicosed tributaries of the vein lie in anal columns at 3-,7-,and 11-o’clock positions. (C)
A, normal tributary of superior rectal vein within the anal column. B, varicosed tributary of superior rectal vein forming internal homorroids. C, positions of varicosed tributaries of the vein.

15. External Hemorroids :
Are varicosities of tributaries of inf. Rectal vein.
They are covered by m.m of lower ½ of anal canal or skin & commonly associated with internal hemorrhoids.
Innervated by inf. Rectal nerves, so they are painful & sensitive to pain,temp, touch & pressure.
It is recognized as a small acute tender swelling at the anal margin.

16. Perianal Abscesses :
Produced by fecal trauma to anal mucosa , or infection of anal fissure (due to tearing of anal valve), or infection of anal mucosal gland.
Types : Submucous abscess Subcutaneous(beneath perianal skin) Ischiorectal abscess pelvirectal abscess (bet.ampulla of rectum & upper surface of levator ani.
Ischiorectal abscess may involve the opposite fossa by spread of infection across midline behind anal canal.

17. Anal Fissure :
In chronic constipation … the anal valves may be torn down to the anus forming the fissure.
It is elongated linear ulcer which lies most commonly in midline posteriorly.
It is a very painful condition specially during defecation because the fissure extends to the lower ectodermal part of anal canal which is supplied by somatic nerve (inf.rectal nerve).
Anal fissre is examined under local anesthesia.

18. Anal Fistula :
Due to inadequate treatment of anal abscesses ,leading to fistula.
It opens between the anal canal lumen., and skin close to anus.
If the abcess opens onto only one surface, it is known as a sinus.
The most important part of sphincteric mechanism of anal canal is the anorectal ring ,it consists of : 1-int. sphincter puborectalis part of levator ani deep part of ext.sph.
Damage to ano-rectal ring will produce fecal incontinence.

19. Cancer and lymph drainage of lower Anal Canal :
Lower ½ of m.m.of anal canal is drained to superficial inguinal L.N.
Cancer of lower ½ of anal canal leads to secondary deposits in inguinal L.N.

21. Urogenital Triangle It is bounded It lies in diamond -shaped perineum.
Anteriorly… by pubic arch.
Laterally … by ischial tuberosities.
Posteriorly : transverse line passing through the 2 ischial tuberosities.
It lies in diamond -shaped perineum.
Urogenital Triangle

22. Fascia of Urogenital Triangle :
Superficial fascia : fatty layer (fascia of camper) : it is continuous with fat of ischiorectal fossa + superficial fascia of thigh. In scrotum, the fat is replaced by smooth muscle – dartos muscle membranous layer (colles’fascia) : it is attached posteriorly to posterior end of urogenital diaphragm/laterally to pubic arch/anteriorly, it is continuous with : the fascia of scrotum (or labia majora) , fascia of penis, membranous layer of superficial fascia of abdomen (Scapa’s fascia).

23. Urogenital Diaphragm
It is a musculofascial diaphragm ,lies in anterior part of perineum (in urogenital triangle) , filling in the gap of pubic arch.
It is formed by sphincter urethrae & deep transverse perineal Ms ,which are enclosed between the superior fascial layer & inferior fascial layer (or perineal membrane).
The closed space between superficial & deep layers of fascia is known as Deep perineal pouch.
The opened space between the urogenital diaphragm above/ and membranous layer of superficial fascia below is called – superficial perineal pouch, which is anteriorly communicates with the space between superficial fascia of abdomen & anterior abdominal Ms. Laterally, it is closed by its attachment to pubic arch.

24. Contents of Male & Female Urogenital triangle
In Male : Penis Scrotum.
In Female : External genitalia (Clitoris) Orificies of Urethra and /Vagina.

25. Contents of Male Urogenital Triangle
The root of penis is formed of 3 masses of erectile tissue : the bulb and right +left crura of penis.
The bulb lies in midline and is attached to undersurface of urogenital diaphragm. It is covered by bulbospongiosus muscle. It is continued forward into body of penis forming the corpus spongiosum It is traversed by the urethra.
Each crus is attached to side of pubic arch and covered by ischiocavernosus muscle. The 2 curura converge anteriorly into the body of penis forming corpora cavernosa.
The body of penis, +glans penis, containing the external urethral meatus.
Contents of Male Urogenital Triangle

26. Prostatic urethra : it is 1 ½ inch-widest & it is the most dilatable part.
Membranous urethra : ½ inch long, lies within the urogenital diaphragm ,surrounded by sphincter urethrae muscle ,it is least dilatable part of urethra
Penile urethra :6 inch long, enclosed in the bulb, corpus spongiosum and glans of penis.
-The part of urethra that lies in glans penis is dilated to form fossa terminalis.
-The bulbourethral glands open into penile urethra below urogenital diaphragm.
-The external meatus is the narrowest part of entire urethra.
Male urethra :

27. Blood supply/ Lymph drainage /innervation of penis :
Arteries : 1-Corpora cavernosa : by deep artery of penis Corpus spongiosum : by artery of bulb + dorsal artery of penis…..all of these arteries are branches of internal pudendal arteries.
Veins : drain into internal pudendal veins.
Lymph drainage : skin : into superficial inguinal L.Ns. / Deep structures : into internal iliac L.Ns.
Nerve supply : pudendal N. + pelvic plexus.

28. Contents of Male Urogenital Triangle
Scrotum & its wall : skin superficial fascia : smooth dartos muscle (replace fatty layer of abdominal wall) + Colles’s fascia (membranous layer of superficial fascia) External spermatic fascia from external oblique Cremasteric fascia from internal oblique Internal spermatic fascia from fascia transversalis Tunica vaginalis : is a closed sac that covers anterior, lateral, and medial surfaces of testis.

29. Blood supply/ Lymph drainage /innervation of Scrotum
Arteries : 1- external pudendal of femoral artery scrotal branches of internal pudendal arteries.
Veins : as the arteries. drain into femoral or internal pudendal vein.
Lymph drainage : skin : into medial group of superficial inguinal L.Ns. / Testis & epididymis :into Lumbar (para-aortic) L.Ns.
Nerve supply : 1-Anterior surface : by ilio-inguinal Ns.+ genital branch of genitofemoral N Posterior surface : by scrotal branches from perineal N. + perineal branch posterior cutaneous N. of the thigh.

30. Contents of female Urogenital Triangle
External genitalia.
Orifices of urethra & vagina.
The vagina is directed upward & backward.
The cervix pierces its anterior wall.
Its upper ½ lies above pelvic floor within the main pelvis between U.B. anteriorly & rectum posteriorly.
Its lower ½ lies in perineum between urethra anteriorly & anal canal posteriorly.
Supports of vagina : upper 1/3 …levator ani, transverse cervical ,pubocervical, and sacrocervical lig. 2-middlle 1/3 …urogenital diaphragm lower 1/3 …perineal body.

31. Contents of Superficial Perineal Pouch In male :
Root of penis + its covering Ms. As bulbospongiosus (covers bulb of penis on each side) & ischiocavernosus muscles (cover crus penis on each side).
Superficial transvrse perineal Ms
arise from ischial ramus and inserted into perineal body… it fix perineal body in the center of perineum.
All Ms. of pouch+ skin are Supplied by perineal branch of pudendal N.
Perineal body : a small fibrous mass lies at the center of posterior margin of
Urogenital diaphragm/. it gives attachment to : 1-ext.anal sphincter bulbospongiosus muscle superficial transverse perineal Ms.

32. Contents of Superficial Perineal Pouch in Female :
Bulbospongiosus muscle, surrounds orifice of vagina and covers vestibular bulbs.
Ischiocavernosus muscle, covers crus of clitoris on each side.
Superficial transverse perineal muscles.
Perineal body …. Lies between vagina & anal canal.
Perineal branch of pudendal N… suppling muscles & skin (as in male).

33. Contents of Deep perineal Pouch in male :
Membranous urethra …lies in urogenital diaphragm.
Sphincter urethrae muscle circular & transverse Fs.,/supplied by perineal branch of pudendal N.
Bulbourethral glands …ducts pierce perineal membrane to enter penile urethra.
Deep transverse perineal Ms. One on each side, small muscle Lie posterior to sphincter urethrae muscle., inserted into perineal body. It help fixation of perineal body.
Internal pudendal vessels.
Dorsal N. of penis.
Coronal section of pelvis

34. Contents of Deep Perineal Pouch In Female :
Part of urethra .
Part of vagina.
Sphincter urethrae ,which is pierced by urethra & vagina.
Deep transverse perineal Ms., as in male.
Internal pudendal vessels.
Dosal N.of clitoris.
Coronal section of pelvis

35. Pudendal Nerve Block
Indication : during second stage of difficult labor, using forceps delivery and episiotomt.
Area of anesthesia: is the skin of perineum.
Transvaginal procedure : The bony landmark used is ischial spine by passing the neddle through vaginal mucous m On passing sacrospinous ligament, injection of solution is performed around pudendal N.
Perineal procedure : The bony landmark is ischial tuberosity, by palpating it subcutaneously at the buttock The neddle is introduced into pudendal canal -1 in. deep to ischial tuberosity, so local anesthetic drug infiltrates around pudendal N.

36. Injury of perineum during childbirth
The perineal body : is a fibromuscular mass lying between bulb of penis & anal canal in male /and between lower part of vagina & anal canal in female, supporting post. Vaginal wall. It is fixed in position by insetion of perineal Ms. + levator ani (anterior Fs.)./it is much larger in femal than in male.
In most cases during childbirth , there is abrasion of post. Vaginal wall /In spontaneous delivary of child, it results in a severe tear of lower 1/3 of post. Vaginal wall, perineal body, and overlying skin, so lacerations may extend into anal canal and damage the external sphincter.
Breech deliveries + forceps diliveries are usually preceded by an episiotomy, through surgical incision in perineal skin in a posterolateral direction to avoid the anal sphincters

38. Perineal membrane (inferior fascia of urogenital diaphragm) in male is piersed by : 1-urethra.
2-internal pudendal artery dorsal N.of penis.
Perineal membrane in female is pierced by : urethra vagina internal pudendal artery dorsal N. of clitoris.

39. Clinical Notes :
Injury to pelvic floor :during childbirth can result in loss of support of pelvic viscera leading to uterine & vaginal prolapse ,and alteration in position of bladder neck & urethra leading to stress incontinence.
Visceral pelvic fascia and infection : the pelvic fascia in the region of uterine cervix is referred to as parametrium.it is a common site for spread of acute infections from uterus & vagina ,so the infection becomes chronic pelvic inflammatory disease.