Essentials of obstetrics

Front matter

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Preface To The Second Edition

As set forth in the preface to the first edition the object of this work is to place the Essential facts and principles of Obstetrics within easy grasp of the student. It is intended as an introduction to the more elaborate treatise, and as a guide in following the didactic and the practical teaching of the college course.

Most attention has been given to practical topics. Theoretical discussions, matters of merely historical interest and elaboration of details have in the main purposely been excluded.

Works of this character, in the author's experience, have, within their proper limits, a distinct value in medical teaching. The pupil in any department of learning needs first to master its elements. This once accomplished, a complete and systematic knowledge of the subject becomes a matter of comparatively easy growth.

The present edition represents a complete revision of the work. Much has been rewritten and new matter has been added.

The author will be gratified if the book in its revised form meets Avith the flattering reception accorded the first edition.

Chapter I. Anatomy Of Female Genital Organs

PAGES.

External genitals — The vagina — Internal genitals . 17-44 CHAPTER II.

PHYSIOLOGY OF PREGNANCY.

Physiology of the ovum — Effects of pregnancy on the maternal organism— Signs of pregnancy — Duration of pregnancy — Hygiene of pregnancy . . 45-95

Chapter III. Physiology Of Labor

The mechanical factors of labor — Clinical and mechanical phenomena of normal labor — Management of labor ....... 96-170

Chapter IV. Physiology Of The Puerperal State

Course and phenomena of the puerperal state — Management of the puerperal state — Lactation and nursing — The child — Condition at birth — Management of the newborn child — Artificial feeding — Disorders of the newborn infant . . . . 171-206 vi CONTENTS.

Chapter V. Pathology Of Pregnancy

Diseases of the deciduse — Anomalies of the amnion and the liquor amnii — Disease of the chorion — Anomalies of the placenta — Anomalies of the umbilical cord — Pathology of the fetus — Abortion — Premature labor — Ectopic gestation — Pernicious vomiting and other disorders of pregnancy . . 207-239

Chapter VI. Pathology Of Labor

Anomalies of the mechanism— Anomalies of the expelling powers — Anomalies of the passages — Anomalies of the passenger — Anomalies of labor arising from accidents or disease .... 240-313

Chapter VII. Pathology Of The Puerperal State

Puerperal insanity — Galactorrhea — Mastitis — Puerperal infection . . . . . . .314-329

Chapter VIII. Obstetric Surgery

Induction of premature labor — Induction of abortion — Removal of an abnormally adherent placenta — Forceps — Version — Csesarean section — Porro operation — Symphysiotomy — Embryotomy . . 330-378

ERRATA.

Page 22. Kobalt should read Kobelt.

Page 192. Gauge should read gauze.

Page 192. Forbe's should read Forbes'.

Page 193. Sterilized gruel should read dextrinized

gruel.

Page 194. (Sugar two tablespooufuls) should read

sugar (two tablespooufuls).

ESSENTIALS OF OBSTETRICS.

Chapter I. Anatomy Of Female Genital Organs

For convenience of description the genital organs of the female may be divided into the external and the internal genitals, and the vagina, which connects the one group with the other.

The external genitals of the female together constitute the pudendum, all but the mons veneris, the vidva.

External Genitals.

The external sexual organs of the female are the mons veneris, the labia majora, the labia minora, the clitoris and the hymen.

The Mons Veneris, or the mount of Venus, is the fleshy prominence which overlies the anterior aspect of the pubic bones. Its surface is slightly convex. It is bounded laterally by the groins, above by the hypogastric fold, and below it merges into the labia majora. It consists essentially of fat supported by a reticular framework of fibrous and elastic tissue. Fibers of elastic tissue, some of which are derived from the superficial abdominal fascia, run through the adipose layer in all directions. The round ligament may be traced into the mons on either side. Its integument, which is somewhat thicker than that of the 2

ESSENTIALS OF OBSTETRICS.

abdomen, becomes invested at puberty with a growth ol short, crisp, curly hair ; it abounds in sebaceous and in sweat glands. The hairy growth extends an inch or more

Fig,

Vulva of the virgin. 1. Greater lip of right, side. 2. Fourchette. 3. Small lip. 4. Clitoris. 5. Urethral orifice. 6. Vestibule. 7. Orifice of the vagina. 8. Hymen. 9. Orifice of the vulvo-vaginal gland. 10. Anterior commissure of greater lips. 11. Anal orifice.

above the level of the pubic bones. It is a peculiarity of the female that the hair of the pubic region is limited above by a sharply defined straight or convex line.

ANATOMY OF FEMALE GEXFFAL ORGANS. 19

The Labia Majora, or larger lips, are two prominent rounded folds springing from the mons veneris and extending downward and backward on either side of the median line. At full development they lie in contact with each other in the young nullipara, except when the thighs are strongly abducted — vulva connivens. When shrunken from loss of fatty tissue in old age, or from the effects of childbirth, the labia minora protrude between them — vulva hi cms. They are thickest in front, and taper from before backward. The point of contact in front is spoken of as the anterior, and that behind as the posterior commissure of the vulva. There is, however, no true commissure in the sense of a connecting band at either point.

The covering of the labia majora is skin. The outer surfaces, which are of a somewhat darker color than the surrounding integument, are supplied with hair which is most abundant anteriorly ; the inner surfaces resemble mucous membrane, but are sparsely covered with fine hairs. Both surfaces abound in sebaceous and in sweat-glands. Their internal structure consists chiefly of elastic and adipose tissue, and includes a rich venous plexus. Immediately beneath the skin is a layer of smooth muscular fibers analogous to those of the dartos in the male. Within this is the pudendal sac. It is made up of elastic fibers, and is attached by its neck to the external inguinal ring. Its fundus reaches nearly to the posterior vulvar commissure. Its cervix contains elastic and adipose tissue. The remains of the canal of Nuck may sometimes be traced into the pudendal sac. Each round ligament of the uterus terminates in the corresponding labium. The labia majora are the analogue of the scrotum in the male.

The Labia Minora, or Nymphae, the smaller lips, are two thin folds of delicate skin lying between the labia majora. They are widest toward their anterior extremities, narrowing gradually from before backward. When at rest their inner surfaces are in contact. The outer surfaces merge into the labia majora, the inner are continuous with the vestibule. Anteriorly each subdivides into two subsidiary folds. The superior folds join in front of the clitoris to form the prepuce, the inferior unite and are attached to the under surfaces of the glans to form the frsenum of the clitoris. Posteriorly they are united by the fourchette.

In Bush women and in many Hottentots the smaller labia are hypertrophied, reaching half-way to the knees ; this overgrown structure is known as the Hottentot apron.

In the virgin the nymphaB present the appearance of mucous membrane ; after long exposure from gaping of the vulva they look like skin. They are destitute of hairs and of sweat-glands. Sebaceous glands are found on both surfaces. In general the histological characters of the outer surfaces are those of skin, not of mucous membrane. The minute anatomy of the inner surfaces lies between that of skin and mucous membrane.

The internal structure of the nymphse includes some bundles of unstriped muscular fiber and a superficial capillary venous plexus, but no fat.

The labia minora are richly supplied with nerve fibers.

The Fourchette, or Frenulum Vulvae, is a transverse fold of skin immediately in front of the posterior vulvar commissure. It is scarcely apparent, except when put upon the stretch by separating the labia. It then appears as a tense transverse fold between the posterior commissure and the hymen. In the nulliparous woman its distance from the anal orifice is 3 cm., 1^ inch ; from the base of the hymen nearly 1 cm., I inch.

The Fossa Navicularis is a boat-shaped space which appears between the hymen and the fourchette when the labia are separated.

The Rima Pudendi is the median cleft between the labia of the right and the left sides.

The Clitoris is situated in the median line below the anterior vulvar commissure. It is a very small cylindrical body, and is slightly curved with its convexity outward. It has two corpora cavernosa and a glans analogous to those of the penis, but has no corpus spongiosum, and is imperforate. Continuous with the corpora cavernosa are the crura by which the clitoris is attached to the ischio-pubic rami. The body is attached to the pubic bones by the suspensory ligament. It is concealed behind the skin and is enclosed in a firm fibrous sheath. Its internal structure is made up chiefly of erectile tissue. The only visible portion of the organ is the glans, and this lies partly concealed in the preputial fold formed by the anterior layers of the nympha? as has already been stated. During erection the glans has a thickness of about 5 mm. The entire length of the clitoris is about one inch. Its mucous membrane is richly supplied with nerve papilla?.

Arteries and Vein. — It has two arteries, the dorsal and the profunda, and a dorsal vein. The vascular supply is from the pudic artery. The dorsal vein empties into the vesical plexus and communicates freely with all the surrounding venous plexuses.

The nerve-supply is derived from the internal pudic and from the hypogastric plexus of the sympathetic, and is four

ESSENTIALS OF OBSTETRICS.

or live times more abundant than that of the penis. The clitoris is the chief seat of voluptuous sensation in the female.

Glands. — A few sebaceous follicles are to be found on the glans.

The Vestibule. — This is the triangular surface bounded laterally by the labia minora and below by the margin of

The bulbi vestibuli. (After Kobalt. )

the vaginal orifice. Its covering is mucous membrane. At its apex is the glans clitoridis. Immediately above the middle of its base is the meatus urethral This appears as a small tubercle or prominence with a median cleft. The meatus lies 2 cm., J inch, below the glans clitoridis, and 2.5 cm., 1 inch, above the fourchette, in the nullipara. An intricate plexus of veins immediately underlies the mucous membrane. This is the pars intermedia, so called from the fact that it connects the opposite vestibular bulbs with each other and with the veins of the clitoris.

The bulbi vestibuli are two leech-shaped masses of veins about 3.5 cm. in length, and are situated one on either side of the mesial line behind the labia, opposite the vaginal orifice and the base of the vestibule. In extent they reach from the level of the posterior margin of the vaginal orifice nearly to the clitoris. They lie between the bulbo-cavernosus muscle and the vaginal wall, immediately in front of the triangular ligament. They communicate freely with the veins of the labia, the vagina, the perineum, the glans clitoridis, and with other neighboring venous plexuses. Each is enclosed in a fibrous sheath. Their internal structure comprises, in addition to venous plexuses and connective tissue, some smooth muscular fibers. The bulbs correspond to the bulbs of the urethra in the male.

The Vulvo-vaginal Glands, (Hands of Bartholin or Duverney. — These are the analogues of Cowper's glands in the male. They are two reddish-yellow bodies varying in size from a pea to an almond, lying one on each side of the posterior portion of the vaginal orifice, between the layers of the triangular ligament, sometimes anteriorly to both. They are partly covered by the lower extremities of the bulbi vestibuli. Their ducts, about 1.3 cm., J inch, in length, run along the inner aspects of the bulbi vestibuli, opening just without the base of the hymen at the sides of the vaginal orifice. The secretion, which is a yellowish tenacious mucus, is poured out freely under sexual excitement and during labor.

The Hymen. — The hymen usually appears as a septum, partially occluding the vaginal orifice when the labia are drawn apart. When at rest it protrudes as a loose fold in the vulvar fissure. According to Budin, it is a thinned-out fold of the vaginal wall. Its most common form is that of a crescent, situated at the posterior margin of the introitus, with its concavity looking forward. It may, however, be annular, or may occupy the entire vaginal orifice, being either imperforate or cribriform — perforated with holes — or may have a single central opening with a fimbriated edge. Its histological characters are similar to those of the vaginal wall, yet it has but few muscular fibers. It is usually torn at the first sexual approaches. An untorn hymen is not, however, an infallible mark of virginity, nor is a torn one necessarily evidence that sexual intercourse has been practised.

The Carunculae Myrtiformes. — The carunculse myrtiformes are the remnants of the hymen torn in labor by the passage of the child. They appear as minute fleshy tubercles, three or four in number, skirting the vaginal orifice or at least its posterior margin.

Vessels, Lymphatics, and Nerves of the Pudendum.

Arteries. — The arterial supply of the pudendum is derived from the superficial perineal branches of the internal pudic and from the external pudic artery.

Veins. — The veins accompany the arteries. They form large plexuses and empty into the internal pudic and the inferior branch of the small sciatic. Varicosities are common during pregnancy. The venous plexuses of the labia become turgid during sexual excitement.

Lymphatics. — The lymphatics go matnly to the superfieial inguinal glands, which in turn communicate with the internal or with the external inguinal glands.

Nerves. — The nerve supply, which is abundant, is from the superficial perineal nerve, which is given off from the pudic, the inferior pudendal nerve, which comes from the small sciatic, and from the inferior hypogastric plexus of the sympathetic.

The Vagina.

The vagina is that part of the genital tract between the uterus and the pudendum. Its direction is nearly parallel with the plane of the pelvic brim. It terminates below in the hymen or its remnants ; the upper part of the tube, which surrounds the cervix, is the roof or fornix of the vagina. The part of the upper extremity behind the cervix is the posterior, that in front the anterior fornix ; the lateral portions of the vaginal roof are spoken of as the lateral fornices. The posterior is deeper than the anterior fornix, owing to the higher attachment of the posterior vaginal wall to the cervix.

Relations. — As already stated, its upper extremity is attached to the uterine cervix a little below the middle of its length, the lower portion of the cervix projecting into the vagina nearly at a right angle. The posterior wall for about one-fourth of its length is in relation at the vaginal roof with the retro-uterine fold of peritoneum, the cul-de-sac of Douglas. Its lower end is united with the so-called perineal body ; at its middle portion, over about half its length, it is connected with the rectum by a loose connective tissue. The upper part of the anterior wall is loosely attached to the bladder ; the lower half is intimately connected with the urethra, the latter being incorporated in it.

Laterally the fornices are in relation with the bases of the broad ligaments ; below the fornices the vagina is attached on either side to the levator ani fascia.

The recto-vaginal septum. — The united portions of the rectal and the posterior vaginal walls form the recto-vaginal septum.

The vesico-vaginal septum is formed by the union of the posterior wall of the bladder with the anterior vaginal wall.

The urethro-vaginal septum is the partition between the urethra and the vagina.

The Shape of the vagina when distended is approximately that of a truncated cone with its larger end up. When at rest it is a collapsed tube, the anterior lying in contact with the posterior wall. Its cross-section in the adult presents the shape of an H, the limbs of which have a slight inward convexity. Its orifice, the introltus vagince, is nearly circular. The vaginal axis is approximately a straight line.

The Size of the vagina is larger in women who have practised sexual intercourse than in virgins, and is much increased in child-bearing women.

The length of the anterior wall in the virgin is 6.3 cm., 2 J inches, that of the posterior wall 9 cm., 3| inches, or a little more. The walls, however, are extremely distensible, and in parous women they become permanently enlarged and relaxed, sometimes attaining the length of 10 to 12 cm., 4 to 4 J inches. The width of the canal at the widest part is about 4 cm., If inch, in the virgin ; in women who have borne children it is frequently 7 cm., 2 j inches.

Structure. — The vagina has three coats : the external or fibrous coat ; the middle or muscular coat ; the internal coat or mucous membrane.

1. The fibrous coat is a prolongation of the recto- vesical fascia.

2. The muscular coat consists of an inner circular and au outer longitudinal layer of unstriped muscular fibers. It is thickest near the vaginal orifice, thinnest in the upper part of the vagina. A band of voluntary muscular fibers, the bulbo-cavernosus muscle, encircles the vaginal orifice.

3. The mucous coat is of a light pink color. It presents two median ridges, one on the anterior and one on the posterior wall. Transverse ridges, cristce, run outward on either side from the longitudinal ones. The median columns with the transverse crista? are known as the cohimnce vagince. These structures are more marked on the anterior than on the posterior wall, and on both are most conspicuously developed near the vaginal orifice. They are rarely found at all above the lower two-thirds of the tube. They are more or less completely effaced by child-bearing and by catarrhal inflammation of the vagina. The mucous membrane of the lower portion of the vagina lies in loose folds when the canal is closed. Its surface is studded with papilla?. The epithelium is of the squamous variety.

The arterial supply of the vagina is chiefly from the vaginal artery. The upper extremity of the tube receives branches from the uterine and the lower from the pudendal artery. These vessels anastomose with one another and with the vesical and rectal arteries. They all spring from the anterior division of the internal iliac.

The veins correspond, but they first form plexuses entirely around the canal, one in the external coat and one in the submucous layer of connective tissue. They communicate with the hemorrhoidal, vesical, pudendal and pampiniform plexuses. None of these veins has valves.

The Lymphatics. — The lymphatics of the lower fourth of the vagina join with those of the pudendum, terminating in the inguinal glands. Those from the remaining portion of the vagina unite with those from the cervix uteri and empty into the internal iliac glands.

The nerves are derived from the fourth sacral and the pudic of the spinal system, and from the lower hypogastric plexus of the sympathetic.

Glands. — The existence of true secreting glands, mucous glands, is by most anatomists denied. The vaginal secretion has an acid reaction, due to the presence of an acidproducing bacillus.

The Urethra. — Intimately connected with the lower portion of the anterior vaginal wall is the urethra. Though not a generative organ, it is of obstetric interest, and is therefore described.

Situation. — From the midpoint of the base of the vestibule the urethra passes backward beneath the pubic arch to the bladder. In the lower three-fourths of its length it is embedded in the anterior vaginal wall. It is supported by the pubo-vesical ligament, and it pierces the layers of the triangular ligament in the same manner as does this canal in the male. The portion of the canal between the layers of the triangular ligament is encircled by the compressor ure three muscle. The general direction of the canal is nearly parallel with the pelvic brim.

Shape. — Its shape is straight or very slightly curved, with its convexity downward and backward. When at rest its mucous membrane lies in longitudinal folds which are especially marked at the upper extremity. Its meatus is a vertical slit ; its vesical end is not funnel-shaped, as sometimes described ; the canal terminates abruptly in the bladder.

Size. — The length of the urethra is about 4 cm., If inch, its average diameter is 6 mm., \ inch. It is largest at the vesical end, smallest at the meatus, and is very distensible.

Structure. — It has two muscular coats, an outer circular and an inner longitudinal layer and a mucous membrane.

The epithelium of the urethral mucosa in the lower portion of the tract is of the squamous type ; toward the upper extremity it is of the transitional form, like that of the vesical mucous membrane.

The vascular and the nervous supply are the same as those of the vestibule. There is a plexus of large veins around the canal, and another plexus between the two muscular coats.

Glands. — Numerous lacunar and racemose glands are to be found on the surface of the mucous membrane. There are two tubular glands, known as Skene's glands, three-fourths of an inch in length, in the wall of the urethra near its floor, one on either side of the median line. Their orifices lie just within the meatus urethra?.

Internal Genitals.

These include the uterus, the Fallopian tubes and the ovaries.

The Uterus. Situation. — In the erect position of the woman the uterus is situated in the cavity of the pelvis, between the bladder and the rectum, a little nearer to the sacrum than to the pubic bones. When the bladder and

ESSENTIALS OF OBSTETRICS.

rectum are empty its upper border is nearly in the plane of the pelvic brim, its lower border just above the level of a

Fig. 3.

Sagittal section of the pelvis, showing relations of generative organs. 1. Body of the uterus. 2. Cavity. 3. Neck. 4. Cavity of the neck. 5. Intra-vaginal part of the neck. 6. Vagina. 7. Vaginal orifice. 8. Bladder. 9. Urethra. 10. Vesico-vaginal wall. 11. Rectum. 12. Bectal cavity. 13. Anus. 14. Recto-vaginal wall. 15. Perineum. 16. Vesico-uterine cul-de-sac. 17. Utero-rectal cul-de-sac. 18. Pubic symphysis. 19. Small lip. 20. Great lip.

line drawn from the lower end of the symphysis pubis to the tip of the sacrum, or in the plane of the ischial spines and posterior to a central position. The average direction of its long axis is nearly perpendicular to the plane of the pelvic brim. Its position, however, is variable within normal limits. A full bladder pushes it bodily back toward the sacrum and tilts the fundus backward. A dissection of the nulliparous uterus, Section of parous uterus, showing

showing shape of corporeal and cervi- shape of corporeal and cervical cavities, eal cavities, etc. etc.

tended rectum displaces it forward. The upper portion of the uterus is in relation with the small intestines. The latter sink into the upper part of the utero-sacral space and sometimes into the utero-vesical pouch. Posteriorly the uterus is separated from the rectum by a fold of peritoneum, which dips down into the pelvic cavity to the distance of an inch or more below the cervico- vaginal junction. This retro-uterine pouch of peritoneum will be described more fully later. Anteriorly the peritoneum covers about two-thirds the length of the uterus. That portion of the lower third of the uterus between the vagina and the peritoneum is attached to the bladder by loose connective tissue. The lower uterine extremity projects into the upper end of the vagina to the extent of nearly 1.3 cm., J inch. The axis of the uterus forms approximately a right angle with that of the vagina when the former organ is in its usual normal position. Laterally the uterus is in relation with the broad ligaments, presently to be described.

Shape. — The uterus is a hollow muscular body. Its shape is pyriform with its larger end uppermost. It is slightly flattened from before backward, its posterior and its upper surfaces are convex, its anterior aspect nearly flat. Its long axis is straight or slightly curved, with its conca v ity for wa rd .

Size, (a) Nulliparous uterus. — The average measurements of the nulliparous uterus are 2.5 cm., 1 inch, nearly, in thickness antero-posteriorly, 3.8 cm., 1 J inch, in width at the level of the Fallopian tubes, and 6.3 cm., 2J inches, in length.

(6) The parous uterus is approximately 2.5 cm., 1 inch, thick, 5 cm., 2 inches, wide, and 7.5 cm., 3 inches, long. The transverse thickness of the lower end of the uterus, the cervix, is 3.1 cm., 1J inch. The organ undergoes, marked atrophy after the menopause.

Weight. — The nulliparous organ weighs about 28 grams, 1 ounce ; in the parous woman the weight is 43 grams, 1J ounce.

Regional Divisions. — The uterus presents two principal divisions, the body and the cervix.

The body is approximately the upper half of the uterus in the nulliparous, the upper two-thirds in the parous woman.

The isthmus is the slight constriction at the junction of the body and the cervix.

The fundus is that part of the body above the level of the Fallopian tubes.

Divisions of the Cervix. — («) The infra-vaginal portion, or portio vaginalis, is that part of the cervix below the vaginal roof. Its average length in the parous woman is 1 cm., a little less than J inch.

(6) The supra-vaginal portion is that part between the portio vaginalis and the isthmus. Its length in the woman who has borne children is 1.5 cm., a little more than J inch.

Uterine Cavity. — (a) The cavity of the body is somewhat triangular in shape in the nullipara, its anterior and posterior walls lying practically in contact. It has three openings, one communicating with the cervical canal and one with each of the Fallopian tubes.

(b) The cavity of the cervix is slightly flattened from before backward, and is laterally elliptical, thus having an irregular fusiform shape.

The os internum is the upper orifice of the cervical canal, and is about 2.5 mm., -jL- inch, in diameter.

The os externum, or os tincse, is the lower orifice, a little larger than the os internum.

Structure. — The mucous membrane of the body of the uterus is about 1 mm., J§ inch, thick at the fundus and more than twice that thickness at the center of the body. No folds are to be observed in the mucosa of the body of the uterus except, perhaps, at the mouths of the Fallopian 3 tubes. Its epithelium is of the ciliated columnar variety, the cilia, as stated by most anatomists, propelling toward the tubes. According to recent observations of Hofmeier, 1 the ciliary movement is toward the external os. The mucosa of the body is firmly attached to the muscular structures. It abounds in tubular glands, many of which are bifurcated — the utricular glands. These are slightly tortuous, and, with few exceptions, extend to the muscularis ; some of them penetrate it. Generally their direction is oblique to the mucous surface. They are lined with ciliated epithelium. Their secretion is alkaline. Dr. A. W. Johnstone ascribes to the corporeal endometrium a glandular character comparable to that of the lymph-tissues in the walls of the alimentary canal and of other adenoid structures.

The mucous membrane of the cervix is thicker, firmer, and paler than that of the body, and it is united to the muscularis by a distinct submucous layer of loose connective tissue. On the anterior and on the posterior wall it presents a pinnate arrangement of ridges known as the arbor vitce or palmce plicatce. This consists of a median longitudinal ridge from which well-marked lateral processes run outward and upward. Upon and between the ridges of the arbor vitse are numerous racemose glands which are histologically mere inversions of the mucous membrane. In the upper two-thirds of the canal the epithelium on the crests of the transverse ridges of the palmge plicatse is ciliated. Elsewhere on the free surface it is goblet-shaped, without cilia.

The gland-cells are cuboidal and non-ciliated. The epithelium of the lower third of the cervical canal and of the 1 Centralb. f. Gyn., 1893, No. 33.

entire external surface of the portio vaginalis is squamous, like that of the vagina. The secretion of the cervical glands is a clear tenacious mucus having an alkaline reaction.

The muscularis constitutes the greater part of the thickness of the uterine walls. Its fiber is of the unstriped variety. The muscular wall is usually described as consisting of three layers ; but this division into strata cannot be made out except during gestation, and even then the layers are not distinctly separable.

The outer layer, which is very thin, consists chiefly of longitudinal fibers which are continuous with the muscular layers of the Fallopian tubes, the ovarian, round, and uterosacral ligaments.

The middle layer comprises the bulk of the uterine muscle and is a meshwork of interlacing longitudinal and circular bundles.

The inner layer, which is made up of circular bundles, is extremely thin. It surrounds the orifice of the Fallopian tubes and forms a sphincter at the os internum.

The cervix consists mainly of connective tissue. A well-marked band of circular fibers exists in the cervix at the vaginal junction.