Three13 109 Surgical, Radiographic and Endoscopic anatomy of male pelvis

• Also called as superficial perineal fascia
• The superficial fascia  of this region consists of two layers, superficial and deep.
• The superficial layer (Campers fascia) is thick, loose, areolar in texture, and contains in its meshes much adipose tissue, the amount of which varies in different subjects.
• The deep layer of superficial fascia (fascia of Colles) is thin, aponeurotic in structure, and of considerable strength, serving to bind down the muscles of the root of the penis

Scarpa in abdomen,, Colles' fascia in perineum, Dartos in scrotum and penis [@SCarDa]

In front, it is continuous with the dartos fascia of the penis and Scarpa's fascia upon the anterior wall of the abdomen;

On either side, it is firmly attached to the margins of the rami of the pubis and ischium, lateral to the crus penis and as far back as the tuberosity of the ischium.

Posteriorly, it curves around the superficial transverse perineal muscle to join the lower margin of the inferior fascia of the urogenital diaphragm.

In the middle line, it is connected with the superficial fascia and with the median septum of the bulbospongiosus muscle

• Applied anatomy - 
• Infection of superficial perineal fascia (Colles fascia) may spread to the penis and scrotum via Buck and Dartos fascia, or to the anterior abdominal wall via Scarpa fascia, or vice versa. Colles fascia is attached to the perineal body and urogenital diaphragm posteriorly and to the pubic rami laterally, thus limiting progression in these directions. Far-advanced or fulminant Fournier gangrene can spread from the fascial envelopment of the genitalia throughout the perineum, along the torso, and, occasionally, into the thighs

Deep perineal fascia / superficial investing fascia (Gallaudet's) - Bucks fascia in the penis, external spermatic fascia in the scrotum, external oblique in the anterior abdominal wall.

The bulbous urethra is the commonest site of ruptured urethra and periurethraJ abscess following stricture of urethra. So extravasation of urine commonly occur from this part of the urethra.

• The urine first collects in the superficial pouch of the perineum. This pouch is closed above by inferior fascia of the urogenital diaphragm (perineal membrane), closed below by facia of Colles, laterally by ischiopubic rami and posteriorly by continuation of
• the perinea! membrane with the fascia of Colles. So this pouch is open only anteriorly through which urine may come out and travel forwards in the subcutaneou tissue of the scrotum, penis and lower part of the anterior abdominal wall, lying deep to the fascia of Scarpa as it stares deep to the fascia of Colles.

• Why does not urine extend into the thigh or anal triangle?
• - Colles fascia blends with fascia lata 
• - Superficial and deep layers of perineal fascia are are continuous with each other around the superficial transverse perineal muscle

The urine at the time of micturition escapes through the periurethral abscess (P.A.) into the superficial pouch of the perineum (S.P.P.) under the fascia of Colles (FC.). It then spreads into the scrotum, penis and anterior abdominal wall under the fascia of Scarpa (FS)

• The pelvic floor is composed of the pelvic diaphragm
• Extends from pubis anteriorly and coccyx posteriorly

• Composed of
• Levator ani muscle
• - Puborectalis
• - pubococcygeus
• - Iliococcygeus
• Coccygeus (Ischiococcygeus)  [@PR PC IC - पुरै पैसा IC nai IC] 

• Puborectalis 
• 

• Pubococcygeus can be further separated into – puboperinealis, puboprostaticus (male), pubovaginalis (female), puboanalis
• 

• Iliococcygeus
• 

• Opening of the levator ani muscle - levator hiatus
• Allows passage of the urethra, vagina, and rectum.
• The levator plate is created by the fusion of the levator ani muscles in the midline and serves as a shelf on which the viscera rest.

• Nerve supply of levator ani - innervated by divisions of the pudendal nerve, inferior rectal nerve, and perineal nerve,
• There is a constant resting tone to the pelvic floor muscles that help support the pelvic viscera, and play an important role in passive control of urinary and fecal continence.
• Weakening of the levator ani may cause the plate to sag and open the hiatus, predisposing to pelvic organ prolapse

• The pelvic diaphragm is not Flat or bowl-shaped
• 

• Laterally – attached to the tendinous arch of levator ani
• Posterolaterally – attached to the ischial spine
• Posteriorly – attached to the caudal sacrum and coccyx
• Anteriorly – attached to the posterior surface of the pubis
• Midline – fibers form a midline levator raphe

• Support of abdominopelvic viscera (bladder, intestines, uterus etc.) through their tonic contraction.
• Resistance to increases in intra-pelvic/abdominal pressure during activities such as coughing or lifting heavy objects.
• Urinary and faecal continence.The muscle fibres have a sphincter action on the rectum and urethra. They relax to allow urination and defecation.

The borders of the perineum are the pubic symphysis anteriorly, pubic rami and ischial rami anterolaterally, ischial tuberosities laterally, sacrotuberous ligaments posterolaterally, and sacrum and coccyx.

• Consists of
• - Anal Triangle
• - Urogenital Triangle - entire urogenital triangle is bridged by the urogenital diaphragm (Perineal Membrane)

• Also referred to as the central tendon of the perineum. 
• The perineal body is at the central point of the perineum and consists of muscle and collagenous and elastic fibers.
• It is the convergence of the bulbospongiosus, external anal sphincter, and superficial and deep transverse perineal muscles.
• It is posterior to the vestibule of the vagina and anterior to the anal canal and attaches to the posterior border of the perineal membrane.
• Damage to the perineal body during parturition can result in damage to the fibers of the external anal sphincter. An episiotomy is angled laterally to avoid damage to these fibers. 

Virtually every pelvic muscle (superficial and deep transverse perinei, bulbocavernosus, levator ani, rectourethralis, external anal sphincter, striated urethral sphincter) and fascia (perineal membrane, Denonvilliers, Colles, and  endopelvic) insert into the perineal body. At the core of the perineal body are abundant elastin and richly innervated smooth muscle, which suggests that it may have a dynamic role in support. Damage to the perineal body during perineal prostatectomy risks postoperative urinary incontinence

• The weakest point in the pelvic floor, the urogenital hiatus, is bridged by the urogenital diaphragm, a structure unique to humans. 
• Urogenital diaphragm = deep transverse perineal and sphincter urethrae
• The superior fascia of the urogenital diaphragm is a continuation of the inferior fascia of the levator ani (pelvic diaphragm), and inferior fascia is the perineal membrane. 
• Many studies have disputed the use of term urogenital diaphragm and started using the term perineal membrane for the 3-dimensional musculofascial expansion across the urogenital triangle. It attaches laterally to the pubic arch and posteriorly attaches to the perineal body

• The pelvic fasciae are continuous with the retroperitoneal fasciae.
• Divisions
• - Outer stratum  - endopelvic fascia, continues with fascia transversalis
• - Intermediate stratum – around the vessels and nerves supplying the pelvic organs
• - Inner strata - just beneath the peritoneum, associated with entire gastrointestinal tract,  forms denonvilliers fascia

• Three important components of the pelvic fasciae:
• - Anteriorly the puboprostatic ligaments
• - Laterally the arcus tendineus fasciae pelvis- extends from the puboprostatic ligament to the ischial spine.
• - Posterior to the ischial spine, the fascia fans out to either side of the rectum and attaches to the pelvic sidewall as the lateral and posterior vesical ligaments.

• [@ Sacral Lumbar Gluteal (SaLu G) VVOR PuG inferior epigastric, Deep circumflex, Pubic, cremasteric सालु जी भरपुग Inferior DPC गर्नु होला, DPC - Deep Circumflex]
• 3 from posterior 
• 7 from anterior - total 10

• 
• Deep dorsal vein – trifurcates into central superficial and two lateral plexus – ultimately drain into internal iliac vein

In half of patients, one or more accessory obturator veins drain into external iliac artery – injury during Lymphadenectomy

The pelvic splanchnic  are preganglionic (presynaptic) parasympathetic nerve fibers that arise from S2, S3 and S4 nerve roots of the sacral plexus. These nerves form the parasympathetic portion of the autonomic nervous system in the pelvis.

• Tetrahedral when empty, ovoid when full
• Relative paucity of muscle in the wall at point
• of attachment of urachus – diverticula formation
• In infants, the true pelvis is shallow – bladder neck in the upper border of the symphysis pubis

• Relationship with bladder - 
• 

The space of Retzius, also referred to as the retropubic space, separates the bladder from the pubic bone and transversalis fascia anteriorly and is composed of loose areolar tissue. Dissection of this space provides access to the anterior bladder wall.

The bladder is bordered on this lateral surface by the perivesical fat, which, when swept medially, exposes the lateral paravesical fossa in which reside the pelvic muscular sidewall, the obturator fossa, and the external and internal iliac vessels.

Within males, the most dependent portion of the peritoneal reflection occurs at the interface between the rectum and posterior bladder wall, referred to as the rectovesical pouch. The corresponding region in females is shallower and occurs between the anterior uterus and posterior bladder wall, referred to as the vesicouterine pouch. Incision of the peritoneal fold in these locations enables mobilization of the posterior bladder wall through caudal dissection within the fascial partition separating the bladder and prostate from the rectum in males or the bladder from the uterus and anterior vaginal wall in females.


Note - The trigone is the most vascular part of the bladder and is formed by an extension of the longitudinal muscle fibres of the ureters over the detrusor muscle. Therefore it appears cystoscopically to be more deeply coloured than the rest of the bladder.

Superior vesical artery - supplies the upper part of the bladder.

Inferior vesical artery supply lower part of the bladder

In females, the uterine and vaginal arteries provide additional blood supply.

Venous drainage begins in a network of small vessels on the lower lateral surfaces of the bladder, which coalesce and travel with the lateral ligaments of the bladder into the internal iliac veins.

• Lateral pedicle - lies lateral to ureter 
• Posterior pedicle - lies medial to ureter, posterior to ureter