FACTS & HINTS

Anatomic Points

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Measurements of the Pelvic Inlet

Used to determine capacityof female pelvis for childbearing

True conjugate diameter

measured radiologicallyon a lateral x-ray

distance from superior border of pubic symphysis to sacral promontory

Transverse diameter: widest distance of pelvic inlet

Oblique diameter: distance from sacroiliac joint to contralateral iliopectineal line

Clinical Points

Fractures of the Pelvis

Alarge force is required to fracture the pelvis and fractures usuallyresult from direct trauma, such as occurs in automobile accidents

The bonypelvis mayfracture at anypoint and there maybe associated damage to pelvic viscera, for example, bladder and urethral rupture can occur with fractures involving the pubis

Pelvic fractures are classified as stable or unstable.

In a stable fracture, the pelvis remains stable and there is onlyone break-point in the pelvic ring with minimal hemorrhage.

In an unstable fracture, the pelvis is unstable with two or more break-points in the pelvic ring with moderate to severe hemorrhage. Signs of a fractured pelvis include: pain in the groin, hip or lower back; difficultywalking; urethral, vaginal or rectal bleeding; scrotal hematoma; and shock as a result of concealed hemorrhage (contained bleeding into the pelvic cavity)

Afracture can be confirmed on x-rayand is seen as a break in continuityof the pelvic ring.

Decubitus Ulcers

Also called pressure sores

Can be a partialor full-thickness loss of skin, underlying connective tissue and can extend into muscle, bone, tendons, and joint capsules. Two thirds of pressure sores occur in patients older than 70 years

Results from prolonged pressure on an area of skin, connective tissue and muscle from a mattress, wheelchair seat, or bed rail. Commonlyoccur in those with poor mobility, bed-bound, poor nutrition, and incontinence.

Can become infected with bacteria from poor skin care, or fecal or urinaryincontinence

The hip and buttock regions account for 67% of all pressure sores, with ischial tuberosity, trochanteric, and sacral locations being most common.

In the sitting position, the ischial tuberositybears the weight of the whole bodyand thus is a prime site of ulceration

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34 Pelvic Floor and Contents

STUDYAIMS

At the end of your study, you should be able to:

State the structures that form the pelvic floor

Describe the two main muscles that form the pelvic floor and their attachments List the functions of the pelvic floor muscles

Describe the attachments of the peritoneum within the pelvis and the location of the vesicoand recto-uterine pouches in females and rectovesical pouch in males

Understand the organization and function of the pelvic fascia

Describe the clinical problems that mayarise with weaknesses of the pelvic floor muscles

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GUIDE

Pelvis and Perineum: Pelvic Floor and Contents

[Plate 338, Pelvic Diaphragm: Female (continued)]

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[Plate 339, Pelvic Diaphragm: Female (Continued)]

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[Plate 341, Pelvic Diaphragm: Male (Continued)]

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[Plate 342, Pelvic Viscera and Perineum: Female]

Pelvic Floor

Formed bythe pelvic diaphragm

Funnel-shaped

Muscular partition from the pubis to the coccyxand from lateral wall to lateral wall

Separates pelvic cavityfrom perineum inferiorly

Transmits urethra, vagina (in females) and anal canal

Muscles of Pelvic Floor

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The pelvic diaphragm is composed of two paired muscles

Levator ani

Coccygeus Levator ani muscle

Paired muscle

Principal muscle of pelvic floor

Supports pelvic contents

Activelymaintains position of pelvic viscera

Arcus tendineus: a thickened line of the fascia over the obturator internus muscles running in an arching line from the pubis to the ischial spine

Central perineal tendon or perineal body

Afibromuscular bodyextending from the perineum into the urogenital hiatus

The site of numerous muscle attachments in the perineum Components of the levator ani muscle

Pubococcygeus

Is anterior part of levator ani Main contributor to the levator ani

Arises from the posterior bodyof the pubic bone and anterior part of the arcus Tendineus

Runs posteriorlyto attach to the anococcygeal ligament and the coccyx

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Iliococcygeus

Posterior part of the levator ani Is thin and poorlydeveloped

Arises from the posterior part of the arcus tendineus and the ischial spine Attaches to the anococcygeal raphe and the coccyx

Puborectalis

Athickened band of muscle best seen inferior to the pubococcygeus

Unites with its partner to make a U-shaped sling around the rectum at its junction with the anus

Has a sphincter-like action bypulling the anorectal junction forward and contributing to anal continence Medial muscle fibers of the pubococcygeus border the urogenital hiatus

Most anterior fibers insert into the urethra

Other fibers sweep behind the vagina or prostate and insert into the central perineal tendon, and are called the levator prostatae or pubovaginalis

Coccygeus muscle

Reinforces pelvic floor posteriorly

Arises from ischial spine

Inserts on lower two sacral and upper two coccygeal segments

Blends with sacrospinous ligament on its external surface Innervation of the levator ani and coccygeus muscles

Levator ani innervated bybranches from the anterior rami of S3-S4 spinal nerves

Puborectalis also innervated bybranch of pudendal nerve (S2,3,4)

Coccygeus supplied bybranches of the anterior rami of S4-S5 spinal nerves Functions of the levator ani

Acting together raise the pelvic floor to increase abdominal pressure, such as when coughing, sneezing, urinating, defecating, lifting heavyobjects.

Important in voluntarycontrol of micturition (urinating)

Supports pelvic viscera Supports head of the fetus

Muscles Lining the Lateral Walls of the Pelvis

Obturator internus muscle

Proximal attachment: pelvic surfaces of ischium and ilium and obturator membrane

Distal attachment: greater trochanter of femur

Innervated bynerve to obturator internus (L5, S1-S2)

Lateral rotator of thigh

Piriformis muscle

Proximal attachment: pelvic surfaces of S2-4 segments of sacrum, sacrotuberous ligament

Distal attachment: greater trochanter of femur

Innervated byventral rami of S1-S2 spinal nerves

Lateral rotator of this

Muscle	Proximal Attachment (Origin)	Distal Attachment (Insertion)	Innervation	Main Actions
Obturator internus	Pelvic aspect of obturator	Greater trochanter of femur	Nerve of	Rotates external thigh
	membrane and pelvic bones		obturator	laterally; abducts flexed
			internus	thigh at hip
Piriformis	Anterior surface of second to	Greater trochanter of femur	Ventral rami	Rotates external thigh
	fourth sacral segments and		of S1-S2	laterally; abducts flexed
	sacrotuberous ligament			thigh; stabilizes hip joint
Levator ani	Bodyof pubis, tendinous arch	Perineal body, coccyx, anococcygeal	Ventral rami	Supports pelvic viscera;
	of obturator fascia, and ischial	raphe, walls of prostate or vagina,	of S3-S4,	raises pelvic floor
	spine	rectum, and anal canal	perineal
			nerve
Coccygeus	Ischial spine and	Inferior sacrum and coccyx	Ventral rami	Supports pelvic viscera;
(ischiococcygeus)	sacrospinous ligament		S4-S5	draws coccyxforward

Pelvic Fascia

Occupies space between peritoneum and muscles of the pelvic floor and walls

Parietal pelvic fascia lines the internal surface (facing the pelvic cavity) of the muscles of the floor and walls Visceral pelvic fascia invests each of the pelvic organs

Visceral and parietal fascia are continuous where organs penetrate pelvic floor

Where theyare continuous, fascia thickens to form the tendineus arch of pelvic fascia (arcus tendinous fasciae pelvis)

Arches are bilateral bands running from pubis to sacrum, adjacent to viscera Puboprostatic ligament

Pubovesical ligament Sacrogenital ligaments

Between parietal and visceral fascia is endopelvic fascia

Matrixor filler material

In certain areas, condenses and becomes more fibrous to form fascial "ligaments" or septa Major condensation is the hypogastric sheath

Runs from lateral pelvic wall to pelvic viscera

Separates retropubic space from presacral space

Serves as a conduit for vessels and nerves

Transverse cervical (cardinal) ligaments are part of hypogastric sheath

Runs from lateral wall to the uterine cervixand vagina

Uppermost part is beneath broad ligament and transmits the uterine artery Is sufficientlyfibrous to provide passive support for the uterus

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Uterosacral (female) or genitosacral (male) ligaments Septa separate the pelvic organs and include

Vesicovaginal septum

Rectovesical septum

Rectovaginal septum

Weakness of the pelvic floor muscles or in the pelvic fascia, which support the pelvic organs, can result in prolapse of the pelvic organs, e.g., vaginal or rectal prolapse.

Pelvic Contents

[Plate 343, Pelvic Contents: Female]

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[Plate 344, Pelvic Viscera: Female]

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[Plate 345, Endopelvic Fascia and Potential Spaces]

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[Plate 346, Pelvic Viscera and Perineum: Male]

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[Plate 386, Lymph Vessels and Nodes of Pelvis and Genitalia: Female]

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[Plate 399, Female Pelvis: Vagina-Urethra]

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Female Pelvic Viscera and Perineum See:

Section 5-4: Urinary Bladder

Section 5-5: Uterus, Vagina and Supporting Structures

Section 5-9: Rectum

Male Pelvic Viscera and Perineum See:

Section 5-4: Urinary Bladder

Section 5-8: Testis, Epididymis, and Ductus Deferens

Section 5-9: Rectum

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