The document discusses the pelvic parts and relationship of the fetus to the pelvis during labor and delivery. It describes the diameters of the fetal skull and pelvic outlet. It then explains the various terms used to describe the fetal position including lie, presentation, presenting part, attitude, denominator, and position. Finally, it outlines the cardinal movements that make up the mechanism of labor, including engagement, descent, flexion, internal rotation, crowning, extension, restitution, external rotation, and expulsion of the trunk.

2. PELVIC PARTS

4. Diameters of Pelvic Outlet

6. Fetal Skull:

7. Anteroposterior Diameters:
Diameters of Fetal Skull:

8. Transverse Diameter:

9. RELATIONSHIP OF FETUS TO PELVIS
1. LIE:
Relationship of the long axis of the fetus to
the long axis of the centralized uterus or
maternal spine.
3 types – Longitudinal, Transverse or
Oblique.

11. 2. PRESENTATION:
Part which occupies lower pole of the uterus.
Cephalic, Podalic or Shoulder.
3.PRESENTING PART:
Part of the presentation which overlies the
internal os & felt by examining finger
through cervical opening.

15. 4. ATTITUDE:
Relation of different parts of the fetus to one another.
3 types – Flexed, Deflexed & Extension.

16. 5.DENOMINATOR:
Arbitrary bony fixed point on the presenting part,
comes in relation with the various quadrants of the
maternal pelvis.
6.POSITION:
Relation of the denominator to the different
quadrants of the pelvis.

18. DEFINITION
The series of movements that
occur on the head in the
process of adaptation during its
journey through the pelvis is
called mechanism of labour.

22. CARDINAL MOVEMENTS
ENGAGEMENT
DESCENT
FLEXION
INTERNAL ROTATION
CROWNING
EXTENSION
RESTITUTION
EXTERNAL ROTATION
EXPULSION OF THE TRUNK

23. 1. Engagement
Greatest transverse diameter of the presenting
part passed through the pelvic inlet.
Engaging diameter - anteroposterior diameter,
may vary depending on the degree of flexion or
extension of the head.
Sensation - occurs 2-3 weeks before labour
begins.

25. 2.Descent
Continuous progress of the fetus as it passes
through birth canal.
Completed with the expulsion of fetus
 Factors facilitating descent:
1.Uterine contraction & retraction
2.Bearing down efforts by woman
3.Straightening of the ovoid fetal especially
after rupture of the membranes
4.Pressure exerted by the amniotic fluid

27. 3.Flexion
As the fetal head descends and meets resistance from
the pelvic floor – Head bent forwards causing its chin to
rest on its sternum.
Presenting diameter – Suboccipitobregmatic (~9.4cm;
shortest anteroposterior diameter)
Increases throughout the labour.
Onset of labour – Suboccipitofrontal;
Greater flexion – Suboccipitobregmatic & Occiput.

29. 4.Internal Rotation
Brings the anteroposterior
diameter of the fetal head into
alignment with the maternal
pelvis.
Turning forwards of whatever
part of the fetus reaches
gutter shaped pelvic floor first.

30. Prerequisites of anterior
internal rotation of head:
 Well-flexed head
 Efficient uterine contraction
 Favourable shape at the
midpelvic plane
 Tone of the levator ani muscles

31. Torsion of neck:
Rotation of shoulders in the same direction to the
extent of 1/8th of the circle.

32. 5.Crowning
Maximum diameters of the head stretches the vulval
outlet without any recession of the head even after the
contraction is over.

34. 6. Extension of the head
Couple of force theory
Driving force – Head in downward
& Pelvic floor – resistance in
upward & forward.
Downward & Upward forces
neutralize & forward thrust helps
in extension.

35. Visible passive movement of
the head due to untwisting of
the neck sustained during
internal rotation.
Rotation of head through
1/8th of a circle in the
opposite direction of internal
rotation.
7. Restitution

36. 8. External Rotation
Movement of rotation of
the head visible
externally due to
internal rotation of the
shoulders.
Shoulders lie in
anteroposterior
diameter.

37. 9. Expulsion of the Trunk
Anterior shoulder
rotates forward,
delivers, followed by
posterior shoulder.
Rest of the trunk
expelled by lateral
flexion.

40. ASSIGNMENT
Discuss & Write in detail about the
mechanisms of labour in the left occiput
anterior position (LOA) giving stress to the
cardinal movements. Submit it on or before
10th September 2020 at Google Classroom
before 4 pm.

41. REFERENCES
STUDENT’S REFERENCES:
1. Hiralal Konar. D.C.Dutta Textbook of Obstetrics, 9th edition, New
Delhi: Jaypee Brothers Publications; 2018. Page no.117-121.
2. Sheila Balakrishnan, Textbook of Obstetrics,2nd edition,
Hyderabad: Paras medical publications; 2014. Page no. 100-105.
3. Fraser M. Diane, Cooper A. Margaret,Myles Textbook for
Midwives, 14th edition,London: Elsevier Publications; 2003. Page
no. 492-495
4. A.V.Raman, Maternity Nursing, 19th edition, New Delhi: Wolter
Kluwer Pvt ltd; 2016. Page no. 314-316

42. TEACHER’S REFERENCES:
1. Hiralal Konar. D.C.Dutta Textbook of Obstetrics, 9th edition, New
Delhi: Jaypee Brothers Publications; 2018. Page no.117-121.
2. Sheila Balakrishnan, Textbook of Obstetrics,2nd edition,
Hyderabad: Paras medical publications; 2014. Page no. 100-105.
3. Fraser M. Diane, Cooper A. Margaret,Myles Textbook for
Midwives, 14th edition,London: Elsevier Publications; 2003. Page
no. 492-495
4. A.V.Raman, Maternity Nursing, 19th edition, New Delhi: Wolter
Kluwer Pvt ltd; 2016. Page no. 314-316.

43.  Annamma Jacob, A Comprehensive Textbook of midwifery and
gynecological nursing, 5th edition, New Delhi: Jaypee
Publications;2019. Page no. 145-147.
 Macdonald Sue, Johnson Gail, Maye’s Midwifery, 15th edition, New
York: Elsevier Publications: 2017. Page no. 511-513.