CHAPTER III.

THE STRUCTURAL ANATOMY OF THE FEMALE PELVIC FLOOR: THE PELVIC FLOOR PROJECTION.

LITERATURE.

STRUCTURAL ANATOMY. Hart-The Structural Anatomy of the Female Pelvic Floor: Edinburgh, 1881. PELVIC FLOOR PROJECTION. Foster-Op. cit. Schroeder-Op. cit. Noch ein Wort über die normale Lage und die Lageveränderungen der Gebärmutter: Arch. f. Gynäk., Bd. IX., S. 68. Schultze-Op. cit. Simpson and Hart-The Relation of the Abdominal and Pelvic Organs in the Female: W. and A. K. Johnston, Edinburgh and London, 1881.

THE STRUCTURAL ANATOMY OF THE FEMALE PELVIC FLOOR. HITHERTO We have regarded the pelvic floor in detail as made up of bladder, vaginal walls, rectum, connective tissue, and peritoneum. In this chapter we purpose considering it in its structural aspect. In its formation, the following functions have been provided for. As compared with the floor of the male pelvis, the female pelvic floor differs in having in it the cleft known as the vagina. Then further, women have to undergo parturition in which the child is born through the vagina, which is then greatly distended. At the same time a woman has resting on her pelvic floor the same abdominal viscera as the male, and her pelvic floor is also subjected to the same strain from intraabdominal pressure. Thus we have to explain how the female pelvic floor has been constructed so as to allow of parturition and yet remain strong enough to resist ordinary intra-abdominal pressure. The question is a structural or architectural one. We study it in this present chapter just as we would study the structure of a box or chair.

In order to understand this question, we must look at the pelvic floor in sagittal mesial section as at fig. 40. In this view we see the pelvic floor or diaphragm stretching from symphysis pubis to sacrum. The anus is to be imagined closed as in life. The first thing to note is the vagina, which is seen as a cleft running upwards in the pelvic floor from hymen to cervix uteri. Its walls are in close apposition (vide figs. passim). They are often erroneously represented apart; in order, as it were, to let the student see the vagina. This is wrong, however.

It is no more necessary to figure the vaginal walls always apart, than it would be always to sketch a man with his mouth open to render it visible. The first idea one gets on looking at such a section is that, owing to the apposition of the vaginal walls, the pelvic floor in the woman is unbroken; and that the vaginal cleft, the introduction of which does weaken the floor somewhat, cuts the floor not perpendicularly to the horizon but obliquely at an angle of about 60°.

The pelvic floor, as seen in this section, is made up of two segments which are known as the pubic and sacral segments. It is of importance to define these exactly.

The Pubic Segment is made up of loose tissue, viz., bladder, urethra, anterior vaginal wall, and bladder peritoneum. It is attached in front to the symphysis pubis. This attachment is a loose one; the bladder and urethra, meeting one another at right angles, are separated from the pubis by the pyramidal deposit of loose fat already described as the retropubic fat deposit. Note specially that the retropubic fat deposit as seen in this section-that of a woman in the dorsal or the erect posture is triangular; and that the peritoneum passes from the anterior abdominal wall on to the fundus of the bladder, just a little above the top of the symphysis.

The Sacral Segment is attached to the coccyx and sacrum; it consists of rectum, perineum, and strong tendinous and muscular tissue. The inferior portion of this segment, the perineum, lies about 1 inch from the symphysis.

So far we have described the mesial attachments of the segments. The pubic segment, however, is also attached on each side to the anterior bony pelvic wall, while the sacral segment is attached in a like manner to the posterior bony pelvic wall. Finally, these two segments blend with one another on the right and left sides of the vagina.

The two segments are thus anatomically contrasted :—

The pubic segment is made up of loose tissue and is loosely attached to the pubic symphysis; the sacral segment is made up of strong tissue and is firmly dovetailed into the sacrum and coccyx.

They are further contrasted functionally :—

The pubic segment is drawn up during labour; the sacral segment is driven down.

The proof for this functional contrast is too elaborate to be given here and will be found given in detail in Dr Hart's atlas. It may be briefly explained, however, that during labour the pubic and sacral segments act like two folding doors. Uterine action pulls up the pubic segment, and drives the child down against the sacral one. This action

is analogous to the way one passes out through two folding doors, where he pulls the one door towards him and pushes the other from him.

As the result of this elevation of the pubic segment, the bladder is drawn above the pubis and its peritoneum stripped off (fig. 56).

Pelvic Floor differentiated in parturition (Braune). The Pubic Segment is drawn up and the Sacral one driven down. Note position of bladder and its peritoneum: for lettered description, see fig. 43.

In addition to the retropubic fat deposit, it should be noted thata. The posterior wall of the bladder is loosely attached to the anterior vaginal wall;

b. The urethra and anterior vaginal wall are closely blended;

c. The posterior vaginal wall and anterior rectal wall are loosely connected, as far down as the apex of the perineal body (fig. 35).

There are three lines of cleavage in the pelvic floor (fig. 57).

1. Physiological, between the vaginal walls; all in front of this line is drawn upwards in parturition.

2. Pathological, between the posterior vaginal and anterior rectal walls; all in front of this is displaced downwards in Prolapsus uteri.

3. Bimanual, between the anterior and posterior rectal walls; all in front of this is displaced on bimanual recto-vaginal examination.

Fig. 57.

Lines of cleavage indicated by dotted lines. From before backwards they are-1. Physiological; 2. Pathological; 3. Bimanual (Hart).

From the structural arrangement of the pelvic floor, it results, as will be shown more fully afterwards, that—

1. There is a definite opening up of the pelvic floor during parturition and when a woman assumes the genupectoral posture with the vaginal orifice opened up;

2. There are produced definite displacements of the pelvic floor when the various specular means of exploring it are employed and under excessive intra-abdominal pressure or hypertrophic growths of the cervix.

The nomenclature employed should be noted.

It is better to speak