Bones of Pelvis:- Pelvis is composed of four bones as
(i) Inn minute bone-2
(ii) Saccrum-1
(iii) Coccyx-1
(1) In nominate Bone:- Ilium
Is chum
Pubis
Two is no & present in either side also called as nameless or Hip bones
Constitute the major part of pelvis
(2) Saccsumi:-
It is a continuing of sacral vertebrae
It has a bean shaped surfaces on upper part called as sacral promontory organ
It is rough an posterior side & smooth an anterior side
(3) Coccyx:-
It is a tail end of pelvis
A very small tail shaped bones under sacrum
Pelvis is divided in to two type:-
(1) False pelvis
(2) True pelvis
Both are divided on the basis of an Imaginary line called as “Brim”
True Pelvis:-
⦁ It is the below the pelvic brim
⦁ It has got very much significance in obstetrics
⦁ Divided in to – Inlet, cavity, Out lit,
Boundaries of true pelvis:-
Ant – Pubic symphysis
Post- Sacrum & coccyx
Lat – Pelvic Muscles & In chial spine
False Pelvis:-
⦁ Formed by Innominance bone (Ilisc part of Innomi)
⦁ The part above the brim
⦁ It has little/no significance in obstetrics
Boundaries-
Ant- Ant abdominal wall
Post- Lumbar vertebrae
Lat- Ilirc fosse
Type:- (a) Gynecoid:-
⦁ Most common found
⦁ Normal female pelvis
⦁ Transversely sounded or blunt (wide not)
(b) Anthropoid:-
⦁ Oval shaped (Monkey like)
⦁ Moderately narrow pubic arch
(c) Android:- Make pelvis
Wedge shaped or angulated
(d) Platypelloid:- Least common
Flat pelvis
Feature Gynaecoid Android Anthropoid Platypelloid
Brim Rounded Heart Shaped Long Oval Kidney Shaped
Fore pelvis Generous Narrow Narrow Wide
Side walls Straight Convergent Divergent Divergent
Ischia Spines Blunt Prominent Blunt Blunt
(Wide notch) (Notch Narrow) (wide notch) (wide notch)
Sciatic Notch Rounded Narrow wide wide
(B/w posterior ilise spine & Ischial spine)
Sub pubic 900 <900 >900 >900
Angle
Incidences 50% 20% 25% 5%
Feature Male Female
1. Structure Large, Herbier Wider, Shall our
More Prominent Wide sciatic
Features Notch
Narrow sciatic Notch
2. General shape Deep funnel Flat bowl
3. Pelvic Brim or Inlet Heats shaped Circular &
More spacious
Diameters Linger
4. Pelvic Cavity Conical & funnel Broad & sound
Shaped
5. Pelvic out let Smaller Larger
6. Sub public angle ‘V’ shaped ‘U’ Shaped
70-750 90-1000
7. Obdurate foramen Large, Oval Shaped Small & triangular
8. Promontory Well Marked Less Marked
9. Saccrum Long & marrow Shirt & wide
10. Coccyx Less Movable More Movable
INLET
Inlet sound shape
Angle of inclination- 550 with the horizontal
Angle > 550 decry in enjoyment and difficulty in descant of the hard < 550 – early engagement.
Sacral angle –True conjugate s.s2
Always > 900
Fix points on pelvic brim:-
⦁ Sacrum promontory (S.P)
⦁ Sacrum ale & wing (S.A)
⦁ Sacrum iliac joint (S.I)
⦁ Ilio-pectineal line (IPL)
⦁ Ilio- pectineal eminence (IPE)
⦁ Sup-Rams of the pelvic bone (SRP)
⦁ Public symphysis (PS)
⦁ Sacral angle
Diameter of Inlet:-
(a) Ant-post:-
(i) True conjugate – (11 cm) b/w midpoint of sacral promontory and inner margin of the upper border of pubic symphysis – It means 11 cm
(ii) Obstetric Conjugate:- (10 cm-10.5 cm) B/w Midpoint of sacral promontory and inner margin of the midline of pubic symphyes
(iii) Diagonal Conjugate – (12 cm)
(Anatomical) B/w midpoint on sacral promontory and lower border of pubic symphusis
(b) Transverse Diameter:- (13 cm – 13.5 cm)
(B/w2 ilcopectined lines)
(c) Oblique Diameter:- (12 cm)
Right a left B/w Socratics joint to apposite iliapubic eminence
CAVITY
Bounded above by inlet and below by plane of least pelne diameter
shape- sound
Plane- Plane of greatest pelvis dimension
Diameter- (a) Ant-post- 11.5 to 12 cm
B/w mid point of pubic symphysis & junction of
(b) Transverse- 12 cm S2 – S3 Vertebrae
OUT –LET
Anatomical Ont Let – Ant – post – 13 cm
Oblic, 12 cm Trsnorse – 11 cm
Obstetric out let is bounded above by the plane of least pelvic dimensions and below by anatomical and let
Shape – Long oval
Plane- Plane of heats pelvic dimensions
Diameters:- (a) Ant- post (11 cm)
B/w Inf border of pubic Symphysis to the tip of sacrum
(b) Transverse- Bispionous diameter (10.5 to 11 cm)
(c) Post sagittal diameter- obstetric out let (5 cm)
(d) Post Sagittal diameter- Anatomical out let (8.5 cm)
Boundaries of Anatomical out let-
Ant- Lower border of pubic symphysis
Let- Ischio pubic ramie, Ischia taberosity and Sacrotuberous lip
Post- Coccyx
Brim Cavity Out Let
Ant-post 11 12 13
Obligue 12 12 12
Transverse 13 12 11
Importance of plane of least pelvis dimensions:-
1. Internal rotation occurs here
2. Most cases of deep transverse arrest occur here.
3. It represent o-station of the head
4. Eternal as is at this level
5. It is a landmark used for pudenda block
Deformed pelvis – Niggles (Absent 1 als)
Robert (Absent both also)
Rachitic (flat brim)
Osteomalscis (Calcium deficiency)
Either way the teacher or student will get the solution to the problem within 24 hours.