FEMALE PELVIS part 2 IN ENGLISH

                                                

                                    FEMALE PELVIS part 2 IN ENGLISH

               watch my youtube video to understand this topic in easy way-

 https://www.youtube.com/watch?v=9R-kWcWAjQE

REGIONS OF PELVIS

1. True pelvis
2. False pelvis

1. The true pelvis : it is the bony canal through which the fetus must pass during birth. It is divided into a brim, a cavity and a outlet.

 The pelvic brim :

›  the superior circumference  forms the brim of the true pelvis, the included space being called the inlet.

›  It is round except where the sacral promontory projects into it.

›   We should be familiar with the fixed points on the pelvic brim that are known as it’s 9 landmarks.

LANDMARKS OF THE BRIM:

1. Symphysis pubis
2. Pubic crest
3. Pubic tubercle
4. Pectineal line
5. Iliopectineal eminence
6. Iliopectineal line
7. Sacroiliac joint
8. Sacral ala or wing
9. Sacral promontory

PELVIC CAVITY

›  The cavity of the true pelvis extends from the brim superiorly to the outlet inferiorly.

›  The anterior wall is formed by the pubic bones and symphysis pubis and it’s depth is 4 cm.

›  The posterior wall is formed by the curve of the sacrum, which is 12 cm in length. Because there is such a difference in these measurements, the cavity forms a curved canal.

›  Its lateral walls are the sides of the pelvis, which are mainly covered by the obturator internus muscle.

›  The cavity contains the pelvic colon, rectum , bladder and some of the reproductive organs.

›  The rectum is placed posteriorly, in the curve of the sacrum and coccyx, the bladder is anterior behind the symphysis pubis.

THE PELVIC OUTLET

›  The lower circumference of the true pelvis is very irregular, the space enclosed by it is called the outlet. Two outlet are described:

1. ANATOMICAL OUTLET
2. OBSTETRICAL OUTLET

ANATOMICAL OUTLET : it is formed by the lower border of each bones together with the sacrotuberous ligament.

OBSTETRICAL OUTLET : It is of greater practical importance because it includes the narrow pelvic strait through which the fetus must pass during delivery. 

The narrow pelvis strait lies between the sacrococygeal joint, the two ischial spines and the lower border of the symphysis pubis .

›  It is the space between narrow pelvic strait and the anatomical outlet. This outlet is diamond – shaped.

2. FALSE PELVIS : It is the part of the pelvis situated above the pelvic brim. 

›  It is formed by the the upper flared – out portions of the iliac bones and protects the abdominal organs. However, the false pelvis has no significance in midwifery.

PELVIC DIAMETERS

1. DIAMETER OF THE BRIM : it has three principal diameters:

›  The anteroposterior diameter or conjugate diameter (11 cm)

›  The transverse diameter (13cm)

›  The oblique diameter (12 cm)

The anteroposterior or conjugate diameter :  it extends from the sacral promontory to the symphysis pubis. Three conjugate diameters can be measured:

01.  the anatomical conjugate: which averages 12cm, is measured from the sacral promontory to the uppermost point of the symphysis pubis.

02. the obstetrical conjugate :which averages 11cm, is measured from the sacral promontory to the posterior border of the upper surface of the symphysis pubis, which is 1.25cm lower. This conjugate is of significance  to midwives as it represents the available space for passage of the fetal head through the bony pelvis

03. the internal or diagonal conjugate : It is also measured antero- posteriorly from the lower border of the symphysis to the sacral promontory. It may be estimated on vaginal examination as part of a pelvic assessment and should measure 12-13cm.

›  The sacrocotyloid diameter: it is passes from the sacral promontory to the iliopectineal eminence on each side and measures 9-9.5 cm.

›  Its importance is concerned with posterior positions of the occiput when the parietal eminences of the fetal head may become caught

The oblique diameter :  it extends from the iliopectineal eminence of one side to the sacroiliac articulation of the opposite side; its average measurement is about 12cm. There are two oblique diameters. left oblique diameter arises from the left sacroiliac joint and the right oblique from the right sacroiliac joint.

The transverse diameter : it extends across the greatest width of the brim; its average measurement is about 13 cm.

2.      DIAMETER OF THE PELVIC CAVITY : The cavity is circular in shape and although it is not possible to measure it’s diameters exactly, they all are considered to be  12 cm.

3.      DIAMETER OF THE PELVIC OUTLET : The outlet which is diamond-shaped has three diameters:  the anteroposterior diameter,  the oblique diameter and  the transverse diameter.

The anteroposterior diameter: it extends from the lower border of the symphysis pubis to the sacrococcygeal joint. It measures 13cm. As the coccyx may be deflected backwards during labour, this diameter indicates the space available during birth.

The oblique diameter:  although there are no fixed points, is said to be between the obturator foramen and the sacrospinous ligament. The measurement is taken as being 12cm.

The transverse diameter : it extends between the two ischial spines and measures 10-11 cm.

It is the narrowest diameter in the pelvis. The plane of least pelvic dimensions is said to be at the level of the ischial spines.

TYES OF PELVIS

1. Gynecoid
2. Platypelloid 
3. Android
4. Anthropoid

OTHER PELVIC VARIATIONS

›  High assimilation pelvis:  This occurs when the 5th lumbar vertebra is fused to the sacrum and the angle of inclination of the pelvic brim is increased. Engagement of the head is difficult but, once achieved, labour progresses normally.

›  Deformed pelvis: Deformation of the pelvis may result from a developmental anomaly, dietary deficiency, injury or disease

›  NAEGELE'S PELVIS : It is a congenial disorder occurs due to arrested development of one ala of the sacrum characterized by  imperfect development of the sacral portion of the sacroiliac joint. Pelvis is obliquely contracted at all levels but more marked in the outlet and Straight iliopectineal line on the affected side. Delivery is done by cesarean section.

›  ROBERT'S PELVIS: It is also a congenial disorder .This is an extremely rare abnormality Ala of both the sides are absent. Sacrum is fused with innominate bones. Delivery is done by cesarean section.

PELVIC INCLINATION-

›  When a women is standing in the upright position, her pelvis is on an incline.

›  The anterior superior iliac spine are immediately above the symphysis pubis in the same vertical plane.

›  The brim is tilted and if the line joining the sacral promontory and the top of the symphysis pubis were to be extended, it would be form an angle of 60° with horizontal floor.

›  Similarly, if a line joining the centre of the sacrum and the centre of the symphysis pubis were to be extended, the resultant angle with the floor would be 30°.

›  When the woman is in the recumbent position the same angles are made with the horizontal, which should be kept in mind when carrying abdominal examination.

AXIS OF PELVIC CAVITY

These are imaginary flat surface at the brim, cavity and outlet of the pelvic canal at the levels of the lines.

CURVE OF CARUS :  a line drawn exactly half- way between the anterior wall and the posterior wall of the pelvic canal would trace a curve.

PELVIC FLOOR

›  The pelvic floor is formed by muscles and the soft tissues that fill the outlet of the pelvis. The most important of these is the strong diaphragm of muscle slung like a hammock from the walls of the pelvis. Through it pass the urethra, the vagina and the anal canal.

FUNCTIONS:

›  The pelvic floor supports the weight of the abdominal and pelvic organs.

›  Its muscles are responsible for the voluntary control of micturition and defecation and play an important part in sexual intercourse.

›  During childbirth it influences the passive movements of the fetus through the birth canal and relaxes to allow the exit of the fetus from the pelvis.

MUSCLES OF PELVIC FLOOR

1. The Superficial layer
2. The deep layer

1.Superficial layer : This layer is composed of five muscles.

• The external anal sphincter encircles the anus and is attached behind by a few fibres to the coccyx.

• The transverse perineal muscles pass from the ischial tuberosities to the centre of the perineum.

• The bulbocavernosus muscles pass from the perineum forwards around the vagina to the corpora cavernosa of the clitoris just under the pubic arch.

• The ischiocavernosus muscles pass from the ischial tuberosities along the pubic arch to the corpora cavernosa.

• The membranous sphincter of the urethra is composed of muscle fibres passing above and below the urethra and attached to the pubic bones. It is not a true sphincter since it is not circular, but it acts to close the urethra.

2. THE DEEP LAYER: This layer is composed of three pairs of muscles, which together are known as the levator ani muscles. They are so called because they lift or elevate the anus.

The pubococcygeus muscle passes from the pubis to the coccyx, with a few fibres crossing over in the perineal body to form its deepest part.

The iliococcygeus muscle : passes from the fascia covering the obturator internus muscle (the white line ofThe perineal bodypelvic fascia) to the coccyx.

The ischiococcygeus muscle passes from the ischial spine to the coccyx, in front of the sacrospinous ligament.

›  Between the muscle layers, and also above and below them, there are layers of pelvic fascia. This is loose areolar tissue that is used like packing material in the spaces. The tissue that fills the triangular space between the bulbocavernosus, the ischiocavernosus and the transverse perineal muscles, is known as the triangular ligament.

THE PERINEAL BODY :This is a pyramid of muscle and fibrous tissue situated between the vagina and the rectum. It is made up of fibres from the muscles of pelvic floor. Its size is 4 cm.