Birth canal obstetric birth canal ppt and it’s

Birth canal

1. BIRTH CANAL
(FEMALE PELVIS, MUSCLES AND
FASCIAE OF PELVIC FLOOR )
FETUS FROM OBSTETRICAL POINT
OF VIEW

2. FEMALE PELVIS(BONY PELVIS)
•Bony pelvis protects pelvic organs (urinary
bladder, rectum, uterus) and surrounding
tissues. Female pelvis forms birth canal,
through which fetus moves during labor.
•Structure of female pelvis is clinically
relevant in obstetrics.

3. BONES OF PELVIS
•Pelvis consists of 4 bones: 2 hip bones,
sacrum and coccyx.

5. Sexual differences of pelvis
Female pelvis Male pelvis
General features Wide and short Narrow and long
Position of iliac wingsMore horizontal More vertical
Sacrum Short and wide Narrow and long
Shape of true pelvis
cavity
Cylindrical Conoid

6. Femal pelvis Male pelvis
Infrapubic angle 90-100 degrees 70-75 degrees
Shape of pelvic inlet, or
superior pelvic aperture
Rounded Heart-shaped

7. Female pelvis Male pelvis
Distantiaspinarum 25-26см
Distantiacristarum 28-29см 21-23 см
Distantiatrochanterica 30-31см
Conjugataexterna 20см
Conjugatavera(true conjugate) 10,5-11 см
Conjugatadiagonalis 12,5-13.0
Transversediameter 13,5 12,8
Obliquediameter 12,0 –12,6 см 12,0 -12,2см
Straightdiameter of true pelvis cavity12. 2 см 10,8 см
Transversediameter of true pelvis
cavity
11,5 см 10,8 см

9. Pelvis is divided into 2 parts:
•superior–false pelvis–and inferior –true pelvis.
Boundary between greater and lesser pelvis is
terminal line, which passes through: superior
border of pubic symphysis and pubic bones,
arcuate lines, promontory.The plane, which lies
between true and false pelvis, is a plain of pelvic
inlet. This plain is very significant in obstetrics.

10. TRUE PELVIS
There are 4 plains of true pelvis:
•I –plain of pelvic inlet,
•II –plain of a wide part of true
pelvis,
•III –plain of a narrow part of
true pelvis,
•IV –plain of pelvic outlet.
The line, which connects centers
of all antero-posterior
dimensions of pelvis, is a
conductive axis of pelvis.

11. I. Plain of pelvic inlet
Boundaries:
•anteriorly–superior margin of
pubic symphysis and iliopubic
eminence,
•Laterally –arcuate lines of ilium,
•Posteriorly –promontory

12. There are 4 dimensions in pelvic inlet:
•Antero-posterior size is a distance between
promontory and the most posterior point of pubic
symphysis. This size is a true conjugate (conjugata
vera). It is equal to 11 cm.
•Transverse size is a distance between the most
lateral points of arcuate lines. It is equal to 13-13,5
cm.
•There are 2 oblique sizes –right and left. These are
the distances between articular cavity of sacroiliac
joint and opposite lateral side of pubic symphyses.
They are equal to 12-12,5 cm.

13. II. Plain of a wide part of pelvic
cavity
Boundaries:
•Anteriorly –middle of the internal
surface of pubic symphysis,
•Laterally -middle of the
acetabulum,
•Posteriorly –place of junction of
2
nd
and 3
rd
sacral vertebrae.

14. There are 2 dimensions in a wide part of pelvic
cavity:
•Antero-posterior size is between junction of S
II
and S
IIIand middle of internal surface of pubic
symphysis; it is equal to 12,5 cm.
•Transverse size is between the most medial points
of acetabulum; it is equal to 12,5 cm.
•There are no oblique sizes in a wide part of pelvic
cavity, because in this part pelvis doesn’t form
non-interrupted bony ring.

15. III. Plain of a narrow part of
pelvic cavity
Boundaries:
•Anteriorly –inferior
margin of pubic
symphysis,
•Laterally –ischial spines,
•Posteriorly –sacro-
coccygeal joint.

16. There are 2 dimensions in a narrow part of
pelvic cavity:
•Antero-posterior size is between sacro-
coccygeal joint and inferior margin of pubic
symphysis. It is equal to 11-11,5 cm.
•Transverse size is between ischial spines. It
is equal to 10,5 cm.

17. IV. Plain of pelvic outlet
Boundaries:
•Anteriorly –inferior margin of pubic
symphysis,
•Laterally –ischial tubers,
•Posteriorly –apex of coccyx.

18. There are 2 dimensions in pelvic outlet:
•Antero-posterior size is between apex of coccyx
and inferior margin of pubic symphysis. It is equal
to 9,5 cm. During vaginal birth coccyx can decline
1,5-2 cm posteriorly. And antero-posterior size
reaches 11,5 cm.
•Transverse size of pelvic outletconnects internal
surfaces of ischial tubers. It is equal to 11 cm.

19. Thus, in pelvic inlet the largest size is a
transverse size. In a wide part of pelvic
cavity antero-posterior and transverse sizes
are equal. In a narrow part and pelvic outlet
antero-posterior sizes are larger than
transverse ones.

23. Pelvicometer

24. Measurement of pelvis
•Distantia spinarum –
distance between anterior
superior iliac spines–25-
26 см.
•Distantia cristarum –
distance between the most
lateral points of iliac crests
–28-29 см.
•Distantia trochanterica –
distance between greater
trochanters of femur–30-
31 см.

25. •Conjugata externa is
an antero-posterior size
of pelvis.Woman lies
on the side, inferior leg
is flexed in hip and knee
joints,superior leg is
extended.One branch of
pelvicometer is put on
the superior margin of
pubic symphysis,
another one is put on the
upper angle of sacral
rhombus. It is equal to
20-21 cm.

26. Solovyov’s index
•Circumference of the hand at the wrist joint
•If Solovyov’sindex is less than 14 cm:
True conjugate=External conjugate-8 cm
•If it is equal to 14-15 cm: true conjugate=external
conjugate-9 cm
•If it is more than
15 cm: true
conjugate=extern
al conjugate-10
cm

27. Diagonal conjugate
Diagonal conjugateis a
distance between
inferior margin of pubic
symphysis and
promontory.
It is measured during
vaginal examination
True
conjugate=diagonal
conjugate –1,5-2 cm

28. ТАЗОВОЕ ДНО
•Выход таза закрыт снизу мощным мышечно-
фасциальным пластом, который называют
тазовым дном.
•Часть тазового дна, располагающаяся между
задней спайкой половых губ и
заднепроходным отверстием, называют
акушерской или передней, промежностью
(задняя промежность –часть тазового дна,
располагающаяся между заднепроходным
отверстием и копчиком).

30. HEAD of MATURE FETUS
Cerebral skull of the
fetus consists of 2
frontal, 2 parietal,
2 temporal and 1
occipital, sphenoid
and ethmoid
bones.

31. •The following sutures are
clinically relevant in obstetrics:
•2 Sagittal suture(sutura
sagitalis).
•Frontal suture(sutura frontalis).
•Coronal suture(sutura
coronalis).
•Lambdoid suture(sutura
lambdoidea)
•Anterior and posterior fontanelles
are also significant

32. Sizes of the head of mature fetus
•Fronto-occipital diameter
(diameter fronto-occipitalis) is
between glabella and external
occipital protuberance. It is equal
to 12 cm. Circumference is equal
to 34 cm.
•Mento-vertical diameter
(diameter mento-verticalis) –
between the chin and vertex –13-
13,5 cm.Circumference is equal
to 38-42 cm.
•Suboccipito-bregmatic size
(diameter suboccipito-
bregmaticus) –between
suboccipital fossa and anterior
angle of anterior fontanelle
(bregma) –equal to 9,5 cm.
Circumference is equal to 32 cm.
•Suboccipito-frontal diameter
(diameter suboccipitio-frontalis) –
betweensuboccipital fossa and
hairline of the forehead –equal to
10 cm. Circumference is 33 cm.
•Vertical diameter(diameter
verticalis, s. trashelo-bregmaticus)
–between bregma and hyoid area
–equal to 9,5-10 cm.
Circumference is equal to 32 cm.

33. •Biparietal diameter
(diameter biparietalis) –
is the largest distance
between parietal tubers –
9,25-9,5 cm.
•Bitemporal diameter
(diameter bitemporalis)
is a distance between the
most lateral points of
coronal suture–8 cm.

34. Sizes of fetal trunk
•Transverse size of shoulders is equal to
12 cm. Circumference of shoulder girdle
is 35 cm.
•Transverse size of pelvic girdle(diameter
bisiliacalis) is equal to 9-9,5 cm.
Circumference is 28 cm.

35. Thank you for your
attention!