Obstetrics; a practical text-book for students and practitioners

Front matter

Reference Hibrarp i*mmfsi^r.

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Preface

During a protracted service as medical head of the Sloane Hospital for Women, where over eighteen hundred deliveries annually occur, the author has enjoj^ed exceptional opportunities for_observation and experience in obstetrics; and for several years he has felt the growing sense of a duty to place before the profession and students of medicine the methods of this institution and the results obtained. The present Text-book of Obstetrics has seemed to him the most rational and perhaps the most useful way in which to meet this obligation. It will hardly be necessary to point out to the reader that the work, in the methods advocated, is based upon the statistical results of the Sloane Hospital and upon the experience gained by the author in the hospital and in private practice. Another object of the work has been to present American statistics in obstetrics.

The fact that many of the text-books now before the profession, although very valuable for reference, are too large for the undergraduate student, has long been appreciated by the author; hence in the following pages he has endeavored to cover the subject concisely and to eliminate unnecessary discussion. With this in view he has made no effort to present a complete bibliography of the subject, although references to important articles on most subjects are given.

It will be noticed that the subjects of pelvimetry and the antepartum examination are included in Chapter Y under the Management of Normal Pregnancy. The author maintains that for the proper management of a pregnancy the obstetrician should inform himself at the earliest opportunity as to both the exact size and shape of the pelvic canal, and should ascertain the presentation of the fetus.

Opinions will probably differ as to the wisdom of placing Chapter VI, Multiple Pregnancy, in Part II under Physiological Pregnancy. The author's reason for doing so is that in the majority of instances multiple pregnancy is physiological and the labor not abnormal. The troublesome question is the location of complicated labor in multiple pregnancy. It more logically belongs in Part V under Pathological Labor, but this arrangement would involve a division of the subject of multiple pregnancy

VI PREFACE

and a separation of the parts by many intervenins; chapters, Mhich seemed to the anthor nnwise. He has therefore completed the sul)ject in one chapter even if in discussing the management of compHcated hxbor in multiple i)regnancy he has anticipated methods of treatment.

For great assistance in preparation of the part of the work treating of embryology the author is pleased to acknowledge his obligation to Adam M. Miller, Ph.D., professor of anatomy at The Long Island College Hospital.

In the matter of illustrations, both drawings and ])hotographs, the author wishes to express to ]Mr. K. K. Bosse, of New York, appreciation of his painstaking work.

E. B. C.

New York, 19 1G.

Chapter I. Anatomy Of The Female Generative Organs

The art of obstetrics comprises the study and care of the woman and the product of her conception from the time of her impregnation until subsequent to her deUvery she is able to resume her usual occupation. A thorough knowledge of the factors involved in this process of reproiVICULARIS

Fig. 1. — The vulva.

duction demands a careful study of the female generative organs and those neighboring organs which, although not distinctively " generative/' are intimately associated with the process.

For purposes of description the female generative organs are divided into the external and the internal.

2 (17)

THE EXTERNAL ORGANS OF GENERATION.

The external organs of generation, grouped under the common term of the ndva, or imdendum, inchide the mons veneris, the labia majora, the labia minora, the clitoris, the vestibule with the urethral orifice, the hymen and certain erectile and glandular structures.

It will be seen from Plate I and Fig. 1 that the vulva is bounded in front by the anterior abdominal wall, behind by the perineum, and laterally bv the inner surface of the thighs.'

r^

FOUI^CHETTL

FOSSA NAVICULARS

Fig. 2. — Nulliparous woman, labia separated.

Mons Veneris. — The mons veneris is a cushion of areolar and adipose tissue situated in front of the upper part of the symphysis pubis. It is covered with skin, which after puberty becomes pigmented and thickly set with hair.

Labia Majora. — The labia majora are two folds of modified integument bordering the cleft of the vulva. They are continuous with the mons veneris in front, where, by their junction, they form the anterior commissure; posteriorly they extend to within an inch of the anus, and there becoming very thin, unite in the posterior commissure, or fovrchette, which forms the anterior edge of the perineum.

When the labia majora are separated in the \'irgin or nulliparous woman (Plate II and Fig. 2) there is found between the fourchette and the hymen a depression called the fossa navicularis. After puberty the outer

1 In the illustrations and description of the external generative organs the woman is supposed to be in the lithotomy position, i. e., on the back, with thighs flexed and separated.

PLATE II

Nulliparous Woman. Labia Separated.

For kev see Fiq 2.

THE EXTERNAL ORGANS OF GENERATION 19

surface of the labia majora is deeply pigmented, covered with hair, and abundantly supplied with sebaceous and sudoriparous glands. The inner surface is also covered with skin, near the free border resembling that on the outer surface, but deeper in, more delicate, moist, and resembling mucous membrane. Rudimentary hairs are visible on close inspection and there are numerous sebaceous glands. In well-nourished virgins the labia majora are usually closely approximated and conceal the parts within. In the aged, emaciated and those who have borne many children, the labia majora usually gape.

Beneath the skin of each labium majus there is found a tissue resembling the dartos of the scrotum but thinner; beneath this are layers of adipose, connective, and elastic tissue. At the upper part of each labium there may sometimes be found the remains of the canal of Nuck. The labia majora correspond morphologically to the scrotum in the male.

The Labia Minora or Nymphae. — The labia minora or nymphse are two smaller folds of modified skin lying within the labia majora and extending from the clitoris in front downward and backward to merge into the labia majora, usually about their middle or lower third. In some women they seem to join each other in the posterior commissure. The labia minora are triangular in shape with bases upward. At the clitoris the base of each divides into two portions, the upper uniting with its fellow of the opposite side above the dorsum of the clitoris to form its prepuce; the lower uniting w^ith its fellow just beneath the clitoris to form its frsenum. The labia minora vary greatly in shape and size; they are sometimes asymmetrical and sometimes, as in the Hottentot M^oman, greatly hypertrophied. They are directly continuous externall}^ with the labia majora and internally with the mucous membrane of the vestibule. In the virgin they are usually concealed by the labia majora; their skin is then delicate and moist and greatly resembles mucous membrane.

When, however, as a result of child-bearing or frequent coitus they project beyond the labia majora, they lose more or less of this character and become dry and pigmented. Their surfaces are free from hairs and sudoriparous glands but are richly supplied with sebaceous glands and with sensitive papilla?. Beneath the surface of the labia minora is a vascular connective tissue rich in elastic and smooth muscle fibers but containing no fat.

The Clitoris. — The clitoris, the homologue of the penis in the male is a small erectile organ about an inch long situated between the anterior extremities of the labia majora at the forepart of the vestibule. Like the penis it consists of a glans, a body and two crura; it has a prepuce and a frsenum both derived from the labia minora, and is also provided with a suspensory ligament.

The clitoris differs structurally from the penis in possessing no corpus spongiosum and no urethra, the latter being situated just above the anterior wall of the vagina with its meatus in the base of the anterior triangular portion of the vestibule.

The Glans. — The glans, visible when the labia minora are separated, is a mass of erectile tissue about the size of a small pea and is highly sensitive, being richly supplied with nerves ending in the so-called genital corpuscles.

The glans is surrounded at its base by sebaceous glands secreting a smegma which may be retained by preputial adhesions and give rise to irritation.

The Body. — The body of the clitoris is composed of two corpora cavernosa, similar in minute structure to those of the male, and separated by an imperfect septum.

The Crura. — The crura are the prolongations of the corpora cavernosa which diverge posteriorly to be attached to the ischiopubic rami superficial to the triangular ligament. They are covered by the ischiocavernosi (erectores clitoridis) muscles.

The Vestibule (see Fig. 1). — The vestibule, best understood as the remains of the urogenital sinus, is the space lying between the labia minora and the hymen. It is bounded in front by the clitoris, behind by the fourchette, laterally by the labia minora. Opening into it are the urethra and the ducts of the vulvovaginal glands. The anterior portion of the vestibule is triangular in shape and by some authors the term vestibule is restricted to this triangular area. The meatus urinarius lies in the base of this triangular portion, the mucous membrane surrounding it being usually elevated and corrugated from the encircling non-striated muscular fibers. Near the meatus are often seen the openings of several large mucous crypts.

The Hymen. — The hymen is a thin fold of mucous membrane arising from a reduplication of the lowermost part of the vaginal walls and closing to a greater or less degree the vaginal orifice. In structure it is composed of a connective-tissue framework rich in elastic fibers and supplied with bloodvessels and nerves; it is covered on both sides with mucous membrane. The hymen varies greatly in shape and extent in different individuals, as seen in Figs. 3 to 10. The most usual shape is the crescentic (see Fig. 3), occluding the posterior portion of the vaginal orifice, the concavity looking forward toward the pubes. Other forms are the anmdar, forming a ring about the opening; the fimbriated or fringed; the bilabial with a central longitudinal cleft; the septate with two openings divided by a septum; the cribriform with numerous small openings; and rarely the hymen completely occludes the vagina, forming the imperforate variety. The hymen is usually, though not always, torn during the first sexual intercourse; it is also often torn in a gynecological examination. Its presence intact is therefore not a certain proof of chastity nor its rupture a sure evidence of intercourse. After parturition there remains of the hymen only fleshy tags attached around the vaginal orifice; these are called the carunciilce myrtiformes (see Fig. 10).

The bulbs of the vestibule {bidbi vestibidi) (see Plates III and IV) are two leech-shaped venous plexuses about ap inch in length lyin^ on either side of the vestibule underneath the labia minora; they may be regarded as the cleft homologue of the corpus spongiosum in the male. These venus plexuses, enclosed within a thin fibrous capsule, are rounded

THE EXTERNAL ORGANS OF GENERATION posteriorly but taper anteriorly and are continued forward on each side by means of a venous plexus, the j)<^>'s intermedia,, which communicates with its fellow beneath the clitoris. There is here free communication

Fig. 3. — The crescentic.

Fig. 4. — The annular.

Fig. 5. — The fimbriated.

Fig. 6.— The bilabial.

between the bulbs of the vestibule, the veins of the labia majora and minora, and the veins of the clitoris. The bulbs of the vestibule are overlapped by the bulbocavernosi {constrictores vagince) muscles and by

AX ATOMY OF THE FEMALE GENERATIVE ORGANS their contractions during sexual excitement the hulhs become turgid and erect, tlnis narrowing the vaginal orifice.

The vulvovaginal glands, or glands of Bartholin, are two racemose glands, round or o\"al in outline, lying on either side of the vaginal orifice

Fig. 7. — The septate.

Fig. S. — The cribriform.

mvrtiformes.

usually superficial to the triangular ligament. They are overlapped by the lower extremities of the bulbs of the vestibule. (See Plate III.) They measure about a third of an inch in diameter and their ducts, each about

PLATE III

FIC. 1

The Bulbs of the Vestibule. (Playfair.)

a, bulb of vestibule; 6, muscular tissue of vagina; c,d,e,f, the clitoris and muscles; g, h, i, k, I, m, n, veins of the nymphas and. clitoris communicating with the epigastric and obturator veins.

FIG. 2

The Clitoris. (After Kobelt.)

A, bulbus vestibuli ; C, pars internmedia ; E, glans clitoridis ; F, corpus clitoridis ; H, dorsal vein; L, right crus ; M, vestibule; N, gland of Bartholin.

half an inch in length, open just in front of the hymen on each side. They are homologues of Cowper's glands in the male and secrete a glairy mucus.

Plane of median sagittal section

Plane of lateral sagittal section

Fig. 11. — Anterior view of cadaver indicating lines of median section shown in Figs. 13 and 14 and of lateral section shown in Figs. 15, 16, and 17.

Plane of lateral sagittal section Plane of median sagittal section

Fig 12 —Superior view of cadaver, showing planes of lateral sagittal section (Figs 15, IG^ and 17), median sagittal section (Figs. 13 and 14), and coronal section (Fig. 21).

The vagina, internal generative organs and pelvic floor will be best understood by a careful study of the accompanying illustrations. Figs.

11 to 17 jiiid 21, from frozen sections made for the author by J)r, Frederick T. Van Beuren, Jr., of New York.

The Vagina (see Fig. 13).— The vagina is the canal connecting the external organs of generation with the uterus, the canal through which sexual intercourse takes place and along which the child passes from the uterus to the outside world. It is a musculomembranous canal lying in the median line of the pelvis between the bladder and urethra in front and the rectum behind; it being separated from the latter below by the pyramidal bod>- called the perineum. The vagina is smaller

Body of 5th L. V.

Peritoneum

Prevesical

space Svniphj'sis

"pubis Bladder

mucosa Mods veneris

Urethra

Vaginal

mucosa Clitoris

Labium minus Fourchette

Fig. 13. — Median sagittal section.

below, expanded above into the fornix or vault which receives the cervix. With the exception of the upper expanded portion of the vaginal canal it is normally found collapsed anteroposteriorly ; the anterior and posterior walls lying in contact in the median line, slightly expanded laterally, giving on transverse section the shape seen in Fig, 18, sometimes resembling the letter H. The axis of the canal is somewhat sigmoid in shape corresponding with the forward curve of the rectum, but in general it conforms to the axis of the pelvic canal. The anterior vaginal wall is shorter than the posterior; the cervix, as it were, being set into the anterior wall and shortening it to this extent.

THE VAGINA

The anterior wall measures about 6.5 cm. (2| in.) the posterior wall 9 cm. (3| in.). For convenience in describing organs or conditions felt through the upper expanded portion of the vagina, the fornix or vault is often subdivided into the anterior, posterior, and lateral fornices.

In structure the vaginal wall consists of three coats: (1) an outer, connective-tissue coat derived from the rectovesical fascia; (2) a middle, muscular coat of unstriped muscular fibers in two layers, an outer, longitudinal and an inner, circular layer; and (3) an internal coat of mucous

Rectum

Coccyx

Posterior fornix Anterior fornix

Recto-uterine pouch -

Ixternal sphincter ani Ampulla of rectum

Anal orifice

External sphincter ani Peri- Vaginal muscularis neal body

Fig. 14. — Median sagittal section.

membrane. The mucous membrane is covered with stratified squamous epithelium continuous with the epithelium covering the vaginal portion of the cervix above and the hymen below. The mucous membrane is thrown into two median longitudinal ridges called the columns of the vagina, situated one on the anterior, the other on the posterior wall. From these extend transversely numerous folds, or rug(B. All of these vaginal markings are more distinct below than above, and most distinct on the anterior vaginal wall in a virgin. With the exception of a few tubular follicles in the upper part of the canal the vagina normally has no glands. The acid reaction of the \aginal secretion is at present assigned to the action of several microorganisms.

The rekdiun.s of the vagina are as follows: The upper half of the anterior wall lies in relation with the bladder, the lower half with the urethra. The bladder and upper third of the urethra are separated from the vaginal wall by areolar connective tissue; the lower two-thirds of the urethra lie imbedded within the anterior vaginal wall. The posterior vaginal wall is covered above, for about an inch, by peritoneum as it descends from the uterus to form the pouch of Douglas; its middle portion

Peritoneum Transversalis fascia

Pelvic fascia "White line"- Reetovesical fascia Obturator facia .

Levator ani muscle Anal fascia Deep layer triang. lig. .

Intraligamentous space Superficial layer of triangular ligament

Fig. 15. — Lateral sagittal section.

lies in relation with the rectum, its lower portion diverges from the rectum from which it is separated by the perineal body. The lateral fornices of the vagina lie in relation with the bases of the broad ligaments which extend from the sides of the uterus to the lateral walls of the pelvis.

The bladder and urethra bear such intimate relations to the uterus, vagina and the practice of obstetrics that they will be briefly described here.

The Bladder. — The bladder when empty lies within the true pelvis between the symphysis pubis in front and the uterus and vagina behind (see Fig. 13). The summit in this condition is flattened or depressed

THE BLADDER AND URETHRA so that the cavity of bladder and urethra together appear Y-shaped on sagittal section. The summit of the bladder is covered by peritoneum which is reflected thence forward to line the anterior abdominal wall; backward to cover the uterus. The bladder has a muscular wall lined with mucous membrane. The muscular structure consists of two coats, the outer being circular, the inner longitudinal, which are continued downward over the urethra. The mucous membrane is covered with stratified transitional epithelium. The bladder when distended rises into the abdomen above the pubes and tends to displace the uterus backward.

1st sacral vertebra

Pyriformis - Peritoneum

Rectum

Coccygeus

Levator ani Fig. 16. — Lateral sagittal section.

The Urethra.— The urethra, a canal about 4 cm. (1| in.) in length and 5 mm. in diameter, extends from the neck of the bladder downward and forward to the meatus urinarius in the base of the triangular portion of the vestibule. Its muscular coat, consisting of an outer circular and an inner longitudinal layer, corresponds to, and is continuous with, the muscular coat of the bladder. The mucous membrane is thrown into longitudinal folds by the elastic fibers which are numerous in the submucous layer; it' is covered with stratified transitional epithelium continuous with that of the bladder.

Numerous tubular glands are present and in the Hour of the urethra near the meatus are two tubules of larger size known as Skene's glands.

x\round the meatus urinarius the mueous membrane is often thrown into folds of various shapes, sometimes called urethral labia.

The Rectum. — The only jjortion of the rectum which especially concerns the obstetrician is that part which perforates the pelvic floor and is uncovered by peritoneum. Beginning at the point where the peritoneum is reflected from the anterior surface of the rectum on to the vault of the vagina, forming the pouch of Douglas or recto-uterine pouch (see

Uterus Fallopian tube Body of pubis Bladder Broad ligament Obturator ext.

Obturator int.

Glass rod above superior layer triangular lig.

Crus clitoridis

Glass rod below inferior layer triangular lig.

Intraligamentous space Fig. 17. — Lateral sagittal section.

Fig. 19), the rectum runs for a short distance parallel to the posterior wall of the vagina and is adherent to it. At about 4 cm. (1| in.) above its lower extremity it curves backward away from the vagina to terminate in its external opening, the anus.

The space thus formed by the divergence of the lower ends of the rectum and vagina is occupied by the pyramidal mass of muscular, fibrous and adipose tissue called the perineal body. Below the point of reflection of the peritoneum from the rectal wall the coats of the rectum are muscular and mucous, united by submucous tissue. The

THE RECTUM muscular coat is composed of two layers, an external longitudinal and an internal circular.

The lower extremity of the rectum is guarded by two constricting bands of muscle; the external and internal sphincters. The former is composed of voluntary muscle fibers, while the latter consists of an aggregation of the involuntary circular fibers of the rectal wall.

The External Sphincter. — ^The external sphincter arises from the posterior surface of the coccyx and from the fibrous layer of the skin over it and passes forward to surround the anus. It is composed of two layers, the superficial and deep.

The deep layer of the external sphincter is circular and entirely surrounds the anus. The fibers of the superficial layer at first run parallel, then separate to surround the anal portion of the rectum, then reunite to be inserted into the tendinous centre of the perineum, some of the fibers being continuous in front with the fibers of the bulbocavernosi (constrictores vaginae) muscles (see Fig. 23).

The external sphincter is intimately adherent to the integument surrounding the anus; this integument being pigmented and throwm into radiating folds.

The Internal Sphincter. — The internal sphincter, composed of an aggregation of the circular fibers of the rectal wall, begins about 4 cm. (1| in.) above the anal margin and increases in thickness as it descends until it reaches the anorectal line, then thins out again. Its lower fibers lie below and within the grasp of the external sphincter but are separated from it by a narrow zone of connective tissue. The mucous membrane of the lower end of the rectum is thrown, especially during contraction of the sphincter, into longitudinal folds called the columns of Morgagni or columns of the rectum. The grooves between these columns deepen from above downward and end in the semilunar valves or crypts of Morgagni.

The rectal mucous membrane above the crypts of Morgagni is thrown into irregular horizontal folds most of which disappear when the rectum is distended but at three or four points they usually remain permanent and are called the valves of Houston or the rectal valves. These valves vary in number from three to five. Usually there are three, called the superior, middle and inferior rectal valves (see Fig. 19). The middle valve is the most constant and arises from the right anterior quadrant of the rectal wall about 6 to 9 cm. (2f to 3| in.) above the anal margin. The superior valve arises from the left posterior quadrant 9 to 11 cm. (4| to 5| in.) above the anus and the inferior valve lies in about the

Fig. 18. — Transverse section of the lower portion of the vagina. (Henle.) L, levator ani muscle; R, rectum; U, urethra; V, vagina.

ANATOMY OF THE FEMALE GENEHATIVE ORGANS same quadrant, 25 to 30 millimeters (1 to li in.) above the anal margin.

Lining the bony framework of the true pelvis and largely closing the openings in its wall are two muscles on each side, the obturator intcrnus and the yyriformis.

The Obturator Intemus. — The obturator internus muscle on each side of the pelvis arises from the bony surface between the obturator foramen in front, the great sacrosciatic notch behind, and the iliopectineal line above. It also arises from the inner surface of the obturator

Fig. I'J. — The rectum luid its relations.

membrane, except a little of its lower part, and from the tendinous arch, completing the canal for the passage of the obturator vessels and nerve. It is inserted into the upper border of the great trochanter. The obturator internus muscle thus lines and cushions the greater part of the anterior and lateral wall of the pelvis on each side. The inner surface of this muscle is covered by the obturator fascia.

The Pyriformis Muscle. — The pyriformis muscle arises from the anterior surface of the second, third and fourth sacral segments, between and external to the anterior foramina; from the margin of the great sacrosciatic foramen and from the anterior surface of the great .' xtq-

PELVIC FLOOR sciatic ligament. It is inserted into the upper border of tlie great trochanter, its tendon usually blending with that of the obturator internus. The pyriformis muscle thus helps to form and cushion the posterior and posterolateral wall of the true pelvis.

The nerve supply of the obturator internus and pyriformis muscle is from the sacral plexus.

Pelvic Floor. — Before describing the internal organs of generation it is fitting that the pelvic floor, above which they are placed and from which they gain support should be studied. This pelvic floor, which is bounded externally by skin and internally by peritoneum, closes the irregularly shaped opening at the bottom of the pelvis. Composed chiefly of muscle, the different fascise and connective tissue, it is perforated by the rectum and vagina and in the anterior wall of the latter canal is

Fig. 20. — The pelvic floor, seen from above.

located the lower end of the urethra. Mewed in a median sagittal section (see Fig. 13), the pelvic floor is seen to be divided by the vagina into two portions, an anterior and a posterior, called respectively by Hart the pubic segment and the sacral segment.

During labor the pubic segment is drawn upward; the sacral segment is forced downward.

Stretching across the outlet of the pelvis and with the fascia? above and below forming the chief part of the pelvic floor are two muscles on each side, the levator ani and the coccygeus.

The Levator Ani (see Fig. 20).— The levator ani, the most important muscle of the pelvic floor, consists of two portions, namely the pubococcygeus and ischiococcygeus; the former arises from the posterior aspect of the horizontal ramus of the pubes and extends backward to t.ie last two segments of the coccyx. The inner portion of this pubococcygeus, sometimes called the piiborectalis, sends a few fibers to the urethral and vaginal walls; some to the tendinous centre of the perineum, while others pass to the rectal sheath and some interlace with the fibers of the external sphincter. Behind the rectum the inner fibers of the two pubococcygei are linked together by fascial structures and the companion muscles thus united pass to the anterior surface of the coccyx to be inserted into the ligamentum sacrococcygeum anterius. The outer portions of the pubococcygei, larger than the inner, pass directly from pubes to coccyx.

The ischiococcygeus, the main portion of the levator ani muscle, arises from the white line between the pubes and s])ine of the ischium and from the spine of the ischium, and extends backward, downward, and inward to the sides of the coccyx. It is thus seen that the former idea of the levatores ani blending with each other behind the vagina and behind the anus and forming a U-shaped muscle about the lower ends of these canals is erroneous. As a matter of fact the ischiococcygeus, the main portion of the levator ani, meets its fellow in the median line only when it reaches the coccyx.

It is the attachment of the inner fibers of the jnibococcygeus to the vaginal and rectal walls and the linking of the two pubococcygei in the median line by means of fascial or fibrous structures which gives the apparent sling action in elevating the lower ends of the rectum and vagina when the levatores ani contract.

The nerve supply of the levator ani is from the fourth sacral and the perineal branch of the pudic nerve.

The Coccygeus. — The coccygeus is a thin triangular-shaped muscle which supplements the levator ani in completing the posterior portion of the muscular pelvic floor.

It arises on each side from the spine of the ischium and is inserted into the lateral margin of the coccyx and the last segment of the sacrum.

The coccygei muscles acting with the levatores ani draw the coccyx forward after it has been displaced backward, as in defecation or parturition. ^ The nerve supply is the fourth sacral.

The Pyriformis Muscle. — The pyriformis muscle on either side lies l)ehind the coccygeus and helps to fill in the posterior and lateral portions of the pelvic floor but is of little obstetrical importance.

The strength of the pelvic floor, so-called, depends very largely upon the layers of fascia which serve to unite the various muscles and viscera of the pelvis. This fascia will now be described.

The Pelvic Fascia. — Covering the levatores ani above and lining them below, are two sheets of fascia, derived from the pelvic fascia which is a direct continuation into the pelvis of the transversalis and iliac fascije which belong to the abdomen.

The layer covering the upper surface of this muscular diaphragm is called the rectovesical fascia (see Figs. 21 and 22), and is the upper and inner division of the pelvic fascia which separates from the lower and outer division or ohhtrator fascia along a line called the "white line"

Iliacus Psoas muscle Cecum muscle Ilium

Gluteus medius

Iliopectineal ridge Gluteus minimus

Iliotibial band Pelvic fascia

Obturator int. _ "White line -, Obturator fascia ' Bladder Rectovesical fascia Levator ani Anal fascia Levator ani Deep layer triang. lig.