Functional Morphology

Jean E. Turnquist , Nancy Minugh-Purvis , in Nonhuman Primates in Biomedical Research (2d Edition), Volume ane, 2012

Overview of Perineum

The perineum of nonhuman primates differs from humans in both shape and function and shows considerable variation amidst species. Some species have marked seasonal variation in coloration, prominence of sexual organs, and/or swelling of the skin of the perineum ( Wislocki, 1933). (See also the department "Skin" above.) The perineum is bounded by the base of the tail dorsally and the pubic symphysis ventrally. The lateral extremes of the perineum are the ischial tuberosities (Figure four.12F) which in some primates are covered by ischial calosities. (These are described in detail at the stop of the section "Peel" above.) The perineum includes all of the soft tissue caudal to the pelvic diaphragm.

The deep perineum of both sexes includes the muscular external anal sphincter and the urogenital diaphragm which includes the voluntary sphincter for the urethra (Effigy 4.12F). The roots of all the external genitalia are too found in this region and thus it is traversed by the continuations of various parts of the genital systems of each sex. The external genitalia are structurally similar to those of humans and other mammals. Well-defined columns of erectile tissue are axiomatic in both the penis and clitoris. The amount of development, particularly of the roots of the external genitalia, is species specific. The nerves and arteries of the surface area are similar to those of humans and most other mammals.

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Female Pelvic Floor

In Imaging Anatomy: Chest, Abdomen, Pelvis (Second Edition), 2017

PERINEUM

Location and Clarification

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Perineum is superficial soft tissues below pelvic diaphragm

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When seen from below with thighs abducted, perineum is diamond-shaped

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Bounded anteriorly by symphysis pubis,

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Bounded posteriorly by tip of coccyx, posteriorly by tip of coccyx, and laterally past ischial tuberosities

Divisions

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Perineum is divided by capricious line betwixt ischial tuberosities into urogenital triangle anteriorly and anal triangle posteriorly

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Urogenital triangle

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Bounded anteriorly by pubic bone and pubic arch

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Bounded laterally by ischial tuberosities

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Contents

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Urethra and vagina

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Perineal membrane

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External genital muscles

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Anal triangle

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Anterior boundary is formed past arbitrary line drawn between ischial tuberosities

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Bounded posteriorly by tip of coccyx

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Lateral boundaries

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Ischial tuberosities and sacrotuberous ligament

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Overlapped by border of gluteus maximus muscle

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Contents

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Anus lies in midline

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Ischiorectal fossa on either side

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Anatomy of the Lower Urinary Tract, Rectum, and Pelvic Floor

Kevin J. Stepp , Mark D. Walters , in Urogynecology and Reconstructive Pelvic Surgery (Tertiary Edition), 2007

Perineum

The perineum is divided into 2 compartments: superficial and deep. These are separated by a fibrous connective tissue layer called the perineal membrane. The perineal membrane is a triangular sheet of dense fibromuscular tissue that spans the anterior one-half of the pelvic outlet. It had been called the urogenital diaphragm previously; this modify in name reflects the appreciation that information technology is not a two-layered structure with muscle in betwixt, as had been thought in the by. The perineal membrane provides back up to the vagina and urethra every bit they pass through it. Cephalad to the perineal membrane lies the striated urogenital sphincter musculus, which, as already mentioned, compresses the mid- and distal urethra. The borders of the perineum are the ischiopubic rami, ischial tuberosities, sacrotuberous ligaments, and coccyx. The perineal body marks the bespeak of convergence of the bulbospongiosus muscles, superficial and deep transverse perinei, perineal membrane, external anal sphincter, posterior vaginal muscularis, and the insertion of the puborectalis and pubococcygeus muscles.

The deep perineal compartment is composed of the deep transverse perineus musculus, portions of the external urethral sphincter muscles (compressor urethrae and urethrovaginal sphincter), portions of the anal sphincter, and the vaginal musculofascial attachments.

The neurovascular anatomy of the perineum is illustrated in Figure ii-eight. The motor and sensory innervation of the perineum is via the pudendal nerve. The pudendal nerve originates from S2–S4 and exits the pelvis through the greater sciatic foramen, hooks around the ischial spine, then travels forth the medial surface of the obturator internus, through the ischiorectal fossa in a thickening of fascia called Alcock's canal. Information technology emerges posteriorly and medially to the ischial tuberosity and divides into three branches to supply the perineum: clitoral, perineal, and junior rectal (also called inferior hemorrhoidal). The blood supply to the perineum is from the pudendal artery, which travels with the pudendal nervus to exit the pelvis.

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Pelvic Organ Prolapse in Postmenopausal Women

MAT H. HO , NARENDER N. BHATIA , in Treatment of the Postmenopausal Adult female (Third Edition), 2007

C Perineum and Perineal Body

The perineum lies only inferior to the levator ani muscles and has a border with the pubic curvation anteriorly and the coccyx tip posteriorly. The perineum can exist divided into two triangular portions by the line between the ischial tuberosities. The anterior portion is called the urogenital triangle and contains the vaginal and urethral outlets. The posterior portion is known as the anal triangle and contains the anal canal. The perineal membrane, which travels between the two ischiopubic rami, provides the cardinal support for the urogenital triangle and divides this triangle into superficial and deep compartments.

The perineal body is a pyramidal construction that is located betwixt the anus and vaginal outlet (Fig. 52.3). The bulbocavernosus muscles, the superficial and deep transverse perineal muscles, a portion of levator ani muscles, and the rectovaginal fascia are all inserted into the perineal body (2). The noon of this structure, which is at the level of the lower middle third of the vagina, is attached to the rectovaginal fascia and then to the uterosacral ligaments. This attachment helps to append and stabilize the perineal trunk.

Effigy 52.three. Female perineum and muscles.

 (Reprinted from Skandalakis JE, Gray SW, Mansberger AR Jr, et al. Hernia: surgical anatomy and technique. New York: McGraw-Colina, 1989:244–250.) Copyright © 1989

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Sexual Offenses, Adult: Normal Anogenital Beefcake and Variants

Yard.Y. Bajowa Edozien , in Encyclopedia of Forensic and Legal Medicine (2nd Edition), 2016

Perineum

The perineum is the region between the thighs, bounded by the scrotum and anus in males and by the opening of the vagina and the anus in females ( Effigy 22).

Figure 22. Male and female perineal regions. Boundaries and surface features of the perineal region with projections of the osseous boundaries and muscles of the perineum.

 Reproduced with permission from Moore, K., Dalley, A., Agur, A., 2013. Clinically Oriented Anatomy, seventh ed. Baltimore, Physician: Lippincott Williams and Wilkins.

A transverse line joining the anterior ends of the ischial tuberosities divides the diamond-shaped perineum into 2 triangles (Figure 23).

Effigy 23. The two triangles (urogenital and anal) that together comprise the perineum do non occupy the same aeroplane. The aeroplane between the float and rectum is occupied by internal genitalia and a septum formed during embryonic development equally the urogenital sinus was partitioned into the urinary bladder and urethra anteriorly and the anorectum posteriorly.

 Reproduced with permission from Moore, K., Dalley, A., Agur, A., 2013. Clinically Oriented Anatomy, seventh ed. Baltimore, MD: Lippincott Williams and Wilkins.

The perineal body is the midpoint of the line joining the ischial tuberosities. Information technology is the site of convergence and interlacing of fibers of several muscles (Figure 24), and lies deep to the skin, posterior to the vestibule of the vagina or bulb of the penis and anterior to the anus and anal canal (Figures 25 and 26; Table ane).

Figure 24. Layers of perineum of males and females.

 Reproduced with permission from Moore, K., Dalley, A., Agur, A., 2013. Clinically Oriented Anatomy, seventh ed. Baltimore, Md: Lippincott Williams and Wilkins.

Effigy 25. Fasciae of perineum, median sections viewed from left – in the female person (a) and male (b).

 Reproduced with permission from Moore, Thousand., Dalley, A., Agur, A., 2013. Clinically Oriented Anatomy, seventh ed. Baltimore, MD: Lippincott Williams and Wilkins.

Figure 26. Muscles of perineum. (a) Muscles of superficial perineal pouch. (b) Muscles of deep perineal pouch.

 Reproduced with permission from Moore, K., Dalley, A., Agur, A., 2013. Clinically Oriented Anatomy, seventh ed. Baltimore, Physician: Lippincott Williams and Wilkins.

Table 1. Muscles of perineum

Musculus Origin Class and distribution Innervation Main action
External anal sphincter Skin and fascia surrounding anus; coccyx via anococcygeal ligament Passes around lateral aspects of anal culvert, insertion into perineal body Junior anal (rectal) nerve, a branch of pudendal nerve (S2–S4) Constricts anal canal during peristalsis, resisting defecation; supports and fixes perineal body and pelvic floor
Bulbospongiosus Male: median raphe on ventral surface of bulb of penis; perineal body Male person: surrounds lateral aspects of bulb of penis and about proximal part of body of penis, inserting into perineal membrane dorsal attribute of corpus spongiosum and corpora cavernosa, and fascia of bulb of penis Muscular (deep) co-operative of perineal nervus, a branch of pudendal nerve (S2–S4) Male person: supports and fixes perineal body/pelvic flooring, compresses bulb of penis to expel terminal drops of urine/semen, assists erection by compressing outflow via deep perineal vein and past pushing blood from bulb into torso of penis
Female: perineal body Female: passes on each side of lower vagina, enclosing bulb and greater vestibular gland; inserts into pubic arch and fascia of corpora cavernosa of clitoris Female: supports and fixes perineal trunk/pelvic floor; 'sphincter' of vagina; assists in erection of clitoris (and perhaps bulb of vestibule); compresses greater vestibular gland

Source: Reproduced with permission from Moore, Thousand., Dalley, A., Agur, A., 2013. Clinically Oriented Anatomy, seventh ed. Baltimore, Doc: Lippincott Williams and Wilkins.

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Osteochondral Lesions of the Talocrural joint and Occult Fractures of the Pes and Ankle

Petros Frousiakis , ... Richard Ferkel , in Baxter's the Pes and Ankle in Sport (Third Edition), 2021

Mechanism of Injury

Os perineum fractures are a rare but often overlooked diagnosis in athletes that can be associated with consummate rupture of the peroneus longus tendon and requires a loftier index of suspicion. The bone peroneum is a sesamoid os that can be found in the peroneus longus tendon, frequently establish adjacent to the plantar-lateral aspect of the cuboid. It has been reported in 5% to 26% of the population. 17 It is important to recognize this injury early to plan for direction of an associated tendon injury.

Presentation and Physical Exam

Patients will often present after an inversion talocrural joint injury with a swollen, painful, and occasionally ecchymotic pes and ankle. Clinicians will notice betoken tenderness plantar-laterally along the inferior lateral cuboid expanse and pain with inversion and eversion of the hindfoot.

Imaging

Plain 10-rays will reveal a proximally migrated bony fragment that may be misread every bit a "beneficial" avulsion, or unlike accompaniment ossicles. Radiographic features of an astute fracture of the os peroneum will demonstrate the presence of "cortical discontinuity with nonsclerotic margins" and a "pieces of a puzzle" appearance. xviii A normal-appearing bone perineum volition appear every bit an oval, well-corticated ossicle well-nigh the calcanealcuboid joint.

MRI imaging is essential to evaluate the advent and possible retraction of the peroneus longus tendon and dominion out any other surrounding soft tissue injury. A retracted os peroneum is highly suggestive of a consummate peroneus longus rupture.

Treatment

Handling for an bone peroneum fracture tin can include nonoperative direction when the bone perineum fracture is minimally displaced. 17 Excision of the ossicle with chief repair of the peroneal longus or tenodesis of the peroneus longus to the brevis is most oft the preferred method for managing this injury in the athlete. Repair or tenodeses helps the athlete to avoid loss of eversion strength, and first metatarsal plantarflexion strength. Postoperatively, the talocrural joint is immobilized in a bandage nonweight bearing for iii weeks in slight eversion, followed by a kicking or cast for some other iii weeks. Therapy will begin at 6 weeks with the focus on ankle and subtalar mobilization.

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NEONATAL UROLOGIC EMERGENCIES

Ben O'Neill Donovan , ... Bradley P. Kropp , in Pediatric Urology, 2010

Intralabial Masses

A perineal mass in a newborn daughter should prompt an immediate exam. Appearance alone is suggestive of the diagnosis in most instances; however, an ultrasound scan of the vagina and float is important. Periurethral cysts are the most mutual and are derived from the periurethral glands. They are whitish in appearance, are covered with normal-appearing epithelium, and are located in the anterior vaginal wall, inferolateral to the meatus. 14 No emergent intervention is required; however, incision is curative. Hydrocolpos from an imperforate hymen manifests as a midline jutting mass at the posterior introitus. The mucosa is slightly transparent and appears pearly white. A palpable suprapubic mass may be present. An ultrasound scan confirms the distended fluid-filled vagina and location of the bladder. Incision and drainage is curative.

Vaginal rhabdomyosarcoma (botryoid sarcoma) ordinarily manifests with vaginal haemorrhage and has a distinctive advent of a cluster of grayish masses (agglomeration of grapes) prolapsing through the introitus. xiv Although no immediate surgical intervention is necessary, prompt evaluation in conjunction with the pediatric oncology team is mandatory. A prolapsing ectopic ureterocele may manifest every bit a mass protruding from the urethra. Covered with bladder epithelium, these masses often appear dark in color, bluish or purple, and edematous or even necrotic. Ureteroceles protruding from the urethra may result in float outlet obstruction, and a palpable float may be identified. The prolapsed ureterocele sometimes can be reduced. A Foley catheter should be placed to drain the bladder temporarily and forbid repeat prolapse until the ureterocele can be incised (see department on ureteroceles).

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Acupuncture Points of the Twelve Primary Channels

Claudia Focks , Ulrich März , in Atlas of Acupuncture, 2008

Pathway

The Kidney primary channel begins beneath the petty toe, which is reached by a branch separating from the Bladder principal aqueduct at its endpoint at → BL-67 (zhiyin) (pes Yin-Yang connection of the 2d great circuit).

The Kidney primary channel diagonally crosses the sole of the foot to Child-1 (yongquan) and to Kid-2 (rangu) below the navicular tuberosity, continues to the posterior aspect of the medial malleolus and descends to enter the heel. From here information technology ascends the medial aspect of the lower leg, intersecting with → SP-6 (yinlingquan ) and continuing to arise the posteromedial aspect of the thigh towards the perineum.

In the perineal region the primary channel divides into 2 branches:

the deep, internal branch travels to → Du-ane (changqiang) and ascends aslope the spine to connect with its pertaining zang-Organ, the Kidneys (shen), and its paired fu-Organ, the Float (pangguang). Here it divides into smaller branches which connect with → Ren-iv (guanyuan) and → Ren-3 (zhongji), and, according to some authors, also with → Ren-7 (yinjiao). From the Kidney (shen) a branch ascends to the Liver (gan), runs to and spreads in the Lung (fei), continues to the trachea and terminates at the root of the natural language. From the Lung (fei), an inner branch travels to the Eye (xin), where it meets the Pericardium primary channel (deep Yin-Yin connection). Information technology and so disperses in the chest and reaches → Ren-17 (shanzhong).

the external branch separates in the perineal region and runs to the lower belly at KID-xi (henggu). From the pubic bone it ascends initially 0.v cun lateral to the anterior midline, from the fifth intercostal space (KID-22) two cun lateral to the midline to the infraclavicular fossa.

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Imperforate Anus

Suzanne Fredrickson Mullin MD , in Pediatric Clinical Counselor (2d Edition), 2007

Physical Test

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Audit perineum for:

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Location and size of the anal opening

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Presence or absence of an anal wink

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May need to await 24 hours for intraluminal pressure to build upwardly in lodge to force meconium through a fistula

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If no anal opening is present, careful inspection of the genitourinary (GU) area should exist performed to evaluate for a fistula.

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In males, a fistula may exist found in recto prostatic or rectourethral.

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In females, the fistula may open at the posterior lobby or vaginally.

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Focus on search for associated abnormalities (VACTERL).

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Vertebral abnormalities occur in 33% of patients with anal atresia.

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Spinal dysraphism

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Tethered cord

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Hemivertebrae

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Hemisacrum

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Sacral dysplasia

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Cardiovascular malformations (12% to 22%)

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Most commonly tetralogy of Fallot or ventricular septal defect

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Gastrointestinal malformation (ten%)

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Tracheoesophageal fistula

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Duodenal obstructions

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Malrotation

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Intestinal atresia

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Annular pancreas

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Omphalocele

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Esophageal atresia

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Renal (other GU tract) malformation: fifty% of patients

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Limb abnormalities

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Direction of Labor

Kent Petrie MD , ... Walter L. Larimore Physician , in Family Medicine Obstetrics (Third Edition), 2008

A. Antenatal Perineal Massage

Massage of the perineum in the last weeks of pregnancy has been well studied in two RCTs. Nearly 2400 women were studied in the Labrecque 17 and Shipman xviii trials. Labrecque and colleagues' study 17 of 1527 women compared a policy of perineal massage from 34 or 35 weeks until commitment with no massage control group. Among women having a vaginal delivery who had non had a previous vaginal delivery, 24.3% of massage grouping and 15.i% of command group had intact perineum (NNT = 11). Women who had greater adherence to the programme of perineal massage were even more probable to have an intact perineum. Differences among women with prior vaginal delivery were not statistically significant. No differences were found in women's sense of control, satisfaction, or the incidence of demand for suturing of vulvar or vaginal trauma.

Labrecque and colleagues 19 also assessed the views of women in the intervention arm of this written report. Women in the trial generally found perineal massage to be an acceptable and positive experience. Participants would favor using it again in another pregnancy and would recommend information technology to another significant adult female. They viewed the upshot on their relationship with their partner to be either positive or negative depending on whether the partner participated with performing the massage.

The smaller RCT of 861 women by Shipman and colleagues 18 institute that antenatal perineal massage had some benefit in reducing 2nd- and thirddegree tears, episiotomies, and instrumental deliveries subsequently adjusting for maternal age and babe nascence weight. The perineal tear rates were 69.0% versus 75.1% (p = 0.024; NNT = 16), and the operative delivery rates were 34.6% versus xl.9% (p = 0.034; NNT = xvi). Analysis stratified for female parent's age found a greater do good in women older than thirty.

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