Flashcards in The maternal pelvis, the fetal skull, mechanisms of normal labour and malpositions Deck (40)
What part of the fetal skull is the sinciput?
- extends from the orbital ridges (bridge of the nose) to the anterior fontanelle and the coronal suture
- the sinciput is also called the brow.
What part of the fetal skull is the vertex?
Extends from the anterior fontanelle and the coronal suture to the posterior fontanelle and the lambdoidal suture
What part of the fetal skull is the occiput?
Extends from the posterior fontanell and the lambdoidal suture to the base of the skull
What are the bones of the fetal skull?
2 frontal bones
2 parietal bones
2 temporal bones
1 occipital bone
What is the suture between the two frontal bones?
the frontal suture
What is the suture between the frontal bones and the parietal bones?
the coronal suture
What is the suture that runs between the anterior fontanelle and the posterior fontanelle?
the sagittal suture
What is the suture that runs between the parietal bones and the occiput?
the lambdoidal suture
What is the shape, alternative name and position of the anterior fontanelle?
- diamond shaped
- also called bregma
- at the junction of the frontal, coronal and sagittal sutures
What is the shape, alternative name and position of the posterior fontanelle?
- also called lambda
- bound by the sagittal and lambdoidal sutures
What are the 3 sections of the true pelvis?
What are the landmarks of the pelvic brim from back to front? Think about how these landmarks relate to position
- sacral promontory (Direct OP)
- sacroiliac joint (LOP/ROP)
- iliopectineal line (LOT/ROT)
- iliopectineal eminence (LOA/ROA)
- upper border of the symphysis pubis (Direct OA)
What are the 4 types of pelvis?
oval shaped, parallel sides, dull ischial spines and wide pubic arch (3 fingers)
heart-shaped, prominent ischial spines and narrow pelvic arch
longer front-to-back compared to gynecoid
longer side-to-side compared to gynecoid
What is the shape of the pelvic brim, and what are its anteroposterior, oblique and transverse diameters?
Oval or heart-shaped
wider in the transverse diameter
What is the shape of the pelvic cavity, and what are its anteroposterior, oblique and transverse diameters?
same width in AP and T diameters, allows space for rotation
What is the shape of the pelvic outlet, and what are its anteroposterior, oblique and transverse diameters?
wider in the AP diameter
What is the anatomical name for the top of your hip bones?
What is the anatomical name for your sit bones?
What are the bones of the pelvis?
- 2 innominate bones each with an ilium, ischium and a pubic bone
What is the meeting point of your pubic bones called?
the pubic symphysis
What is the name for the underside of the pubic symphysis?
the pubic arch
What are the 4 pelvic joints?
- the pubic symphysis
between two pubic bones
- two sacroiliac joints
between sacrum and ilium
- the sacrococcygeal joint
between sacrum and coccyx
What is the curve of carus?
- the imaginary line which passes through the centre of the theoretical plane at the pelvic brim, cavity and outlet
- follows the curve of the sacrum
- the anterior wall of the pelvis (the pubic symphysis) is shorter than the posterior wall (the sacrum), which creates a curved canal
what are the landmarks of the pelvic outlet?
- sacrococcygeal joint
- ischial spines
- symphysis pubis
What is moulding (of the fetal skull)?
the change in the shape of the fetal head as it passes through the birth canal, possible due to slight bending and overlapping of the bones of the fetal skull
What is attitude of the fetal skull?
the degree of flexion or extension of the of the fetal head relative to the neck
What part of the fetal skull is the face?
extends from the orbital ridges to the junction of the chin and neck. the chin is called the mentum
What are the names and measurements of the two transverse diameters of the fetal skull?
The bitemporal diameter is 8.2cm and the biparietal diameter is 9.5cm
What are the presenting diameters in a well flexed vertex presentation?
the suboccipitobegmatic (SOB) diameter (9.5cm) and the biparietal diameter (9.5cm). These diameters form a circle and are most effective at dilating the cervix.