FEMALE PELVIS

FEMALE PELVIS:

Definition: Bony pelvis is a bony canal through which the foetus passes during the process of birth. As it forms a bony canal therefore it is called as bony pelvis.

BONES OF THE PELVIS:

1.       2 Innominate or hip bones:   

Each innonimate bone consist of

·         Illium

·         Ischium

·         Pubis

2.       One sacrum Sacrum

3.       One Coccyx

Illium consist of:

1.       Iliac crest

2.       Anterior superior iliac spine

3.       2/5 of the acetabulum

4.       Sacroiliac joint

5.       Posterior superior iliac spine

6.       Iliac fossa

7.       Iliopectineal eminence

8.       Iliopectineal; lines.

Ischium consist of:

1.       2/5^th oif the acetabulum

2.       Ischeal tuberocity

3.       Ischeal spines separate greater and lesser sciatic notches.

4.       Forms lower border of obdurator foramen.

Pubic bones consist of:

1.       1/5^th of the acetabulum

2.       Superior ramus

3.       Inferior ramus

4.       Symphysis pubis

5.       Pubic arch

6.       Obturator foramen (upper border)

Sacrum:

1.       Sacral foramina (8 in numer-4 on either side

2.       Sacral cornua

3.       Hollow of sacrum

4.       Sacral promontory

5.       Al;ae of sacrum

Coccyx:

Fusion of 3-5 rudimentary vertebrae

JOINTS OF PELVIS:

1.       Symohysisi pubis

2.       Two sacroiliac joints

3.       One sacrococcygeal joint.

PELVIC LIGAMENTS:

Ligaments connect two bones

1.       Sacrospinous ligament Æ lateral aspect of the sacrum   to  ischial spines

2.       Sacrotuberous ligament Æ    lateral aspect of the sacrum  to  inner aspect  of ischial tuberosity

3.       Sacroiliac ligament Æ    medial surface of the ilium  to  sacrum

4.       lliolumbar ligament Æ  iliac crest  to  transv lumbar vertebra

CHARACTERISTICS OF CLINICALLY FAVORABLE PELVIS:

1.       Sacral promontory can not be felt

2.       Ischial spines are not prominent

3.       Subpubic arch accept 2 fingers

4.       Intertuberous diameter accept 4 knuckles on pelvic exam

REGIONS OF THE PELVIS:

1.       True pelvis: region below the pelvic brim

2.       False pelvis: region above the pelvic brim

PART OF TRUE PELVIS:

1.       Brim

2.       cavity

3.       outlet

Eight Land marks of brim:

1.       Sacral promontory

2.       Alae or wings of sacrum

3.       Sacroiliac joints

4.       Iliopectineal line

5.       Iliopectineal eminence

6.       Superior ramus of pubis

7.       Ipubic tunbercle

8.       Symphysis pubis

Cavity formed by:

1.       Symphysis pubis

2.       Curve of sacrum

3.       Ligaments and soft tissues.

Pelvic outlet:

1.       Anatomical outlet:  it is diamond shaped bounded anteriorly by the pubic arch laterally by the ischeal tuberosities and posteriorly by the sacrotoberous ligaments and tip of coccyx.

2.       Obstetrical outlet: it is bounded anteriorly by pubic arch, laterally by line passing to ischial spines and posteriorly by sacro-coccygeal joints.

THE MEASUREMENT OF TRUE PELVIS:

A. Oblique diameter

B. Anterioposterior diameter

C. Transverse diameter

D. Brim

E. Cavity

F. Outlet

CONJUGATE OF PELVIC BONE:

1.       OBSTETRIC CONJUGATE: The shortest APD between sacral promontory & symphysis pubis

2.       TRUE CONJUGATE: APD between promontory of the sacrum & superior margin of the symphysis pubis

3.       DIAGONAL CONJUGATE: Distance between sacral promontory & inferior margin of the symphysis pubis

TYPES OF PELVIS:

1- ANTHROPOID

·         25% white women & 50% nonwhite

·         Pelvic brim  APD > TD

·         Long & narrow pelvic canal with long sacrum

·         Straight pelvic sidewalls

2-PLATYPELLOID

·         3% of women

·         Pelvic brim TD >>>APD   Æ kidney shape

·         Sacral promontory pushed forwards

3- GYNECOID

·         Typical female pelvis found in 50% of women

·         Rounded—slightly oval inlet

·         Straight pelvic sidewalls with roomy pelvic cavity

·         Good sacral curve

·         Ischial spines are not prominent

·         Pubic arch is wide

4-ANDROID

·         Typical male pelvis found in 1/3 white women 1/6 non-white

·         Pelvic brim is heart shaped

·         Pelvis funnels from above downwards (convergent sidewalls)

·         Narrow pubic arch

·         Prominent spines

PELVIC INCLINATION:

While standing brim makes an angle of 60^o, cavity makes an angle of 30^o and outlet makes an angle of 15^o.

CURVE OF CARUS: A line draw exactly halfway between the anterior wall and the posterior wall of the pelvic canal.