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Genital System > The Female Pelvis and Fetal Skull > Flashcards

The Female Pelvis and Fetal Skull Flashcards

1
Q

What are the significant obstetric characteristics

A

Sacrum

Coccyx

Ossa Innominata(Os Coxae)

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2
Q

Sacrum

A

Consists of 5 vertebrae that are used to fused, the ant. surface is concave and the ant.-sup. border of the s1 forms the sacral promontory.

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3
Q

Coccyx

A

Consists of four fused vertebrae and gives attachment to the levator ani muscle, coccygeus and the anal sphincters

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4
Q

Ossa Innominata /Os Coxae

A

Joining of the ileum,Ischium and pubis my by means of cartilage that later ossifies.

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5
Q

Ileum

A

Contains a concave ant. surface, the fossa iliac , an upper border, the crista iliaca and the terminal end of the crest ,the ant and post. sup. iliac spines

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6
Q

Ischium

A

Contains 2 large prominences on which you sit, the ischial tuberosities and the ischial spines that are situated post and sup, to this.

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7
Q

Pubis

A

Consists of a body, a sup. and inf. ramus(2 inf rami form the pubic arch). Where the sup. ramus meets the ileum, forms the iliopectineal eminence. The iliopectineal line extends from the pubic tubercle to the sacro-iliac joint-border of the pelvic inlet.

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8
Q

The types of joints which are present in the Pelvis

A

Pubic Symphysis

Sacrococcygeal Joint

Sacro-iliac Joint

Accessory Ligaments:

Sacrotuberous

Sacrospinous

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9
Q

Pubic Symphysis

A

A Secondary cartilaginous joint

Ligaments:

Ant. pubic ligaments(Strong)
Post. pubic ligaments(Weak)
Sup. pubic liagaments(Weak)
Inf. pubic ligaments-Arcuate lig-Strong between the pubic rami

Movements:

Little movement

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10
Q

Sacrococcygeal Joint

A

Secondary cartilaginous joint

Ligaments:

Ant. and Post. scaro-coccygeal ligaments-Strengthen joint

Movements:

Moves Backwards during labour and enlarges the pelvic inlet

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11
Q

Sacr0-iliac Joint

A

Synovial, multi-axial plane joint.

Ligaments:

Ant. saco-iliac ligament-Short and Transverse
Interosseus sacro-iliac ligament-Strong
Short post. sacro-iliac ligament-Short and strong
Long post. sacro-iliac ligament-Long

Movement:

The movement is limited however during pregnancy because the ligaments soften.

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12
Q

Mention the accessory ligaments

A

Sacro-tuberous ligamant

Sacro-spinous ligament

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13
Q

Sacro-tuberous

A

Between the sacrum and the tuberosity of the ischium

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14
Q

Sacro-spinous

A

Between sacrum and the ischial spine

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15
Q

What happens during pregnancy to the ligaments

A

The ligaments become hyperemic and soften due to 2 hormones, relax in and progesterone(both secreted by the corpus luteum and placenta) causing more movement, esp at the sacro-iliac joint and the pubic symphysis

The softening is sometimes so pronounced that it produces symptoms of Sacro-ileitis

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16
Q

The obstetric pelvis

A

It can be divided into the:

True Pelvis
False Pelvis
Axis of Birth Canal
Pelvic Inclination

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17
Q

True Pelvis/Pelvis Minor

A

Inf. to linea terminalis and forms a bony passage for the baby during birth.

  • Curved cylinder
  • Ant border: 5cm long and straight(Symphysis pubic)
  • Post. border: 10-15 cm long and concave(Sacrum)
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18
Q

False Pelvis/Pelvis Major

A

The area between the 2 iliac fossae above the linea terminalis and is part of abdominal cavity that contains intestinal loops

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19
Q

Axis of Birth Canal

A

It is the course taken by the presenting part of the fetus in its passage through the pelvis-direction is initially to post . to inf.

At level of ischial spines direction changes by 90* to proceed ant. and inf.

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20
Q

Pelvic Inclination

A

The normal position of the pelvis when a women is standing upright, is when the SIAS is on the same vertical plane as the pubic tubercle.

Plane of pelvic inlet thus forms an angle of 60* to the horizontal-Pelvic Inclination

If the angle increases, engagement of the fetal head is hampered

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21
Q

Important Pelvic Planes

A

The Pelvic Inlet

The Midpelvis

The Pelvic Outlet

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22
Q

The Pelvic Inlet

Boundaries:

A

Ant: Post.sup. border of the pubic rami and symphysis

Post: Promontorium and the ala of Sacrum

Lat: iliopectinal Line

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23
Q

The pelvic Inlet

Diameters

A

Antero-Posterior(AP):

Conjugata vera: 11.5cm

Conjugata obstetrica: 11 cm-from the promontorium to mid. post surface of symphysis

Conjugata Diagonale: 12.5cm-can be measured from the pubic angle to the middle of the promontorium

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24
Q

The transverse diameter of the Pelvic Inlet

A

Largest possible distance between the iliopectinal lines

90* angle with the AP measurement

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25
The Oblique diameter of the Pelvic Inlet
112.5 From the sacro-iliac joint to oposite the iliopectinal line The left obique diameter is smaller because of the sigmoid colon The right oblique diamter is from right SI(Sacro-iliac) joint The leftoblique diameter is from left SI joint
26
The Midpelvis Boundaries:
It is the plane with the least dimensions. Ant: Subpubic Angle Post; Junction btwn s4,5 Lat: Arcus tendineus, Ischial spine and sacrospinous lig.
27
The Mid pelvis Diameters
AP: 11.5cm From post-inf. border of pubic symphysis to s4,5 junction Tranverse diamter: 10.5 Btwn the spines of the ischium
28
The pelvic Outlet Boundaries:
Ant: Subpubic Angle Post: Sacrococcygeal Joint Lat: Pubic rami and tuberosity(Ant. triangle) and sacrotuberous ligament(Post. triangle)
29
The Pelvic Outlet Diameters
AP: 11.5 From the inferior border of pubic symphysis to saccrococcygeal joint(Tip of coccyx not reliable die to mobility of the joint) Transverse Diameter: 11cm Between the ischial tuberosities
30
Pelvic Classification
The pelvic is classfied into four based on the shape of the inlet: 1. Gynaecoid pelvis 2. Android Pelvis 3. Anthropoid pelvis 4. Platypelloid Pelvis The course of labour is not only determined by the pelvic dimensions but also by the architecture of the pelvis
31
Gynaecoid Pelvis
Inlet: -Almost round,T>AP diameter Ant. segment is large Midpelvis: - ischial spines are not prominent,sacrum is short,wide with prominent curve. - Sacro-ischiadic notch is wide with a long sacrospinous ligt. Outlet: - Wide subpubic angle,>90* - Inf. pubic rami short and concave Course of labour: - Uneventful with normal labour - Fetal head engages in transverse or oblique position - perineal tears do not occur often because of wide subpubic angle
32
Android Pelvis
Inlet: - Heart shaped,promontorium is prominent(dimish available space) - AP diameter>Transverse diameter - Ant. segment narrow Midpelvis: - Sacrum long, straight and narrow. - Ischial spines prominent - Pelvis is funnel shaped - Sacro-ischiadic notch Outlet: - Subpubic angle narrow,70* - Inf. pubic ramus long - AP diameter is smaller Course of Labour: - Fetal head engages in transverse position - Narrow subpubic angle forces head post. and creates perineal tears
33
Anthropoid Pelvis
Inlet: - Oval shaped, AP diameter> than Transverse Diametr - Ant. segment narrow. Midpelvis: - Sacro-ischiadic notch wide - Ischial spines are prominent Outlet: -Subpubic angle is narrow Course of Labour: - Often Occipito-Posterior(OP) position - Usually normal Labour
34
Platypelloid Pelvis
Inlet: -Small AP diameter, long Transverse diameter Midpelvis: -Ischial spines small with long interspinous distance Outlet: -Subpubic angle is wide Course of labour: -Progress of labour stops earlier because of small AP diameter.
35
How to know the type of Pelvis a female has.
These four pelvic shaped very seldom appear exclusively in these pure forms. The pelvic size and shape can be determined by vaginal examinations(Clinical pelvimetry) or radiological examinations(X-ray pelvimetry). Eventually, the most accurate pelvimeter is the fetal head during labour
36
The Mature Pelvis
Aticulation of the fetal skull and the body The fetal skull is attached post. to the vertebral column, thus forming a lever with a short post. arm and a long ant. arm Which explains the tendency pf the fetal skull to flex during labour.
37
What is the obstetric significance of the fetal skull L.L.I.P
- Largest measurement of the fetus - Least pliable part of the baby - Is presenting part of baby - Prone to injury
38
Characteristics of the fetal Skull
Base of skull Cranium Sutures
39
Base of Skull
These bone are firmly uunited and are not compressible,They protect vital centres in the brain stem.
40
Cranium
Consists of 7 bones. At birth the bones are thin and joined by membranes,which allow overlapping during the birth process(moulding). The facilities the accommodation of the fetal skull in the maternal pelvis.
41
Sutures
Membranous spaces between the bones of the cranium. They allow moulding. Sutures are used to determine the exact postion of the fetal head during labour(by vaginal examination). Sagittal Lamboid Coronal Frontal
42
Sagital
Between 2 parietal bones which connects 2 frontanelles and AP plane
43
Lamboid
between 2 parietal bones and occipital bones-transverse planes
44
Coronal
Between 2 pareital bones and 2 frontal bones-transverse plane
45
Frontal
Betweeen 2 frontal bones-AP plane
46
Frontanelles
Intersection of 2 sutures forms a membranous space,known as frontanelles Ant. Frontanelle(Bregma) Post. Frontanelle(Lambda)
47
Ant. Frontanelle(Bregma)
Large and diamod-shaped at the juction of sagittal,coronal amd frontal sutures On examination 4 sutures that radiate from diamond Closes at 18 months
48
Post. Frontanelle(Lamba)
Small and triangular at the junction of sagittal and lambdoid suture. On examination thus only 3 sutures CLoses at 6-8 weeks
49
Landmarks
Occiput: -Post. part of skull, prominence on occipital bone Vertex/Crown -Between ant. and post. frontanelles Sinciput: -Between ant. frontanelle and coronal sutures superior and glabella and orbital ridge inf. Glabella -Prominence between orbital ridges Mentum -Chin
50
Diameters of the fetal skull
Transverse diameters Anteroposterior diameters
51
Transverse diameters of the fetal skull
Biparietal - Widest part of fetal skull - Between external surfaces of pareital bones-9.5 Bitemporal_-Smallest transverse diameter,situated far to ant.-8cm
52
Anteroposterior diameters of the fetal skull
Suboccipito-bregmatic: - Extends from inf. surface of occipital bone to bregma - 9.5 cm - Equal to the biparietal diameter(therefore skull presents as a circle) - Diameter presents when the head is well flexed(LOA/ROA) Occipitofrontal: - Extends from the occiput to the glabella - 11cm - Skull presents as an oval - Diameter presents if skull is in neutal/military attitude(OP) Mentovertical: - Extends from the tip of chin to vertex - 13.5 cm(largest AP diameter) - Skull presents as an oval - Diameter presents in forehead presentation(Normal delivery not possible) Submentobregmatic: - Extends from the juntion of the neck and the lower jaw to bregma - 9.5cm - Skull presents as a circle - Diameter presents in facial presentation
53
Suboccipito-bregmatic
- Extends from inf. surface of occipital bone to bregma - 9.5 cm - Equal to the biparietal diameter(therefore skull presents as a circle) - Diameter presents when the head is well flexed(LOA/ROA)
54
Occipitofrontal
- Extends from the occiput to the glabella - 11cm - Skull presents as an oval - Diameter presents if skull is in neutal/military attitude(OP)
55
Mentovertical
- Extends from the tip of chin to vertex - 13.5 cm(largest AP diameter) - Skull presents as an oval - Diameter presents in forehead presentation(Normal delivery not possible)
56
Submentobregmatic
- Extends from the juntion of the neck and the lower jaw to bregma - 9.5cm - Skull presents as a circle - Diameter presents in facial presentation
57
Definitions which are related to the mechanism of labour
Lie Presenting Part Presentation Attitude Denominator Position Engagement Descent Station Level of head
58
Lie
Relationship between the long axis of the fetus and long axis of the mother: Longitudinal Transverse Oblique
59
Presenting part
Lowest part of the fetus: - Fetal head - Shoulder - Breech
60
Presentation
Part of fetus at the pelvic inlet: - Fetal head:Cephalic-vertex, face,forehead - Breech - Shoulder
61
Attitude
Relation of fetal parts to each other, esp the attitide of the head - Flexion - Varying degrees of extension
62
Denominator
Lowest bony point of the presenting part - Head with vertex presentation-Occiput - Head with facial presentation-Mentum/Chin - Breech presentation-Sacrum - Shoulder presentation-Acromion
63
Position
The relation of the denominator to the quadrants of the pelvis Occipito-anterior(OA)-ROA, OA and LOA Occipito-posterior(OP)-ROP. OP and LOP Occipito-Transverse(OT)-ROT and LOT
64
Engagement
Engagement occurs only once when the largest diameter of the presenting part passes through the pelvic inlet. Cephalic presentation: Biparietal diameter Breech presentation: Bitrochanteric diameter
65
Descent
Continuing process where the fetus is passsing through the birth canal
66
Station
Relation of the lowest bony point of the presenting part to the imaginary line beytween the two ischial spines(expressed in cm as -1,0 and +1) ``` -1= Presenting part above ischial spines +1= Presenting part below the ischial spine ```
67
Level of head
Part of fetal head palpable above the pubic symphysis, expressed in fifths of the fetal head eg. 3/5 fetal head above the pelvis

Genital System (12 decks)

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