Bony Pelvis, Pelvic Fracture and Childbirth Flashcards
List the components of the bony pelvis
2 x innominate (hip) bones
Sacrum
Coccyx
List the components of the pelvic girdle
2 x innominate (hip) bones
Sacrum
(Does not include coccyx)
What are the three parts of an innominate bone?
Ilium
Ischium
Pubis
Which component of the ilium connects the ASIS to PSIS?
Iliac crest
What part of the bony pelvis is the attachment site for the iliacus muscle?
Iliac fossa
List the ANTERIOR components of the ilium
Iliac crest
Iliac fossa
ASIS
List the POSTERIOR components of the ilium
Iliac crest
PSIS
List the main ANTERIOR components of the ischium
Ischiopubis ramus
List the POSTERIOR components of the ischium
Ischial spine
Ischial tuberosity
Which part of the ischium is the ‘part you sit on’?
Ischial tuberosity
List the ANTERIOR components of the pubis
Ischiopubis ramus
Pubic arch
Pubic tubercle
Superior pubis ramus
The angle created by the pubic arch is known as the…
Sub-pubic angle
Give the attachment sites for the inguinal ligament
ASIS
Pubic tubercle
List the main joints of the pelvis and give their types
Sacroiliac joint (synovial) Hip joint (synovial) Pubic symphysis (secondary cartilaginous)
List the ANTERIOR palpable surface landmarks of the pelvis from superior to inferior
Iliac crest
ASIS
Pubic tubercle
Pubic symphysis
List the POSTERIOR palpable surface landmarks of the pelvis from superior to inferior
Iliac crest PSIS Sacrum Coccyx Ischial tuberosity
Which part of the bony pelvis is palpable on vaginal examination? Where can it be palpated?
Ischial spines
Finger breadth into vagina (4 and 8 o’clock)
Ligaments are found…
Across a joint to stabilise it
List the main ligaments of the pelvis and give their attachment sites
Sarcotuberous ligament (sacrum + ischial tuberosity) Sacrospinous ligament (sacrum + ischial spine)
Recognise the main bony landmarks of the pelvis on X-ray
See image
What is the main function of the sacrotuberous and sarcospinous ligaments?
Ensure part of the sacrum is not pushed superiorly when weight is suddenly transferred vertically through the vertebral column e.g. when jumping or during late pregnancy
The sacrotuberous and sacrospinous ligaments are involved in the formation of which two structures?
Greater sciatic foramen (superior)
Lesser sciatic foramen (inferior)
List the components of the pelvic inlet
Sacral promontory
Ilium
Superior pubic ramus
Pubic symphysis
List the components of the pelvic outlet
Coccyx Pubic symphysis Ischial tuberosities Sacrotuberous ligaments Ischiopubic ramus
The pelvic cavity is found between the _____ and the _____
Pelvic inlet
Pelvic floor
Which muscle forms the musculofascial part of the pelvic cavity
Levator ani muscle (pelvic floor)
List the functions of the bony pelvis
Support upper body when sitting/standing
Transfer weight from 1 pole (vertebral column) to 2 poles (femurs) for standing/walking
Attachment form muscles of locomotion and abdominal wall
Attachment for external genitalia
Protect pelvic organs, their blood and nerve supply, venous and lymph drainage
Passage for childbirth
Trauma to the bony pelvis usually results in a single fracture. True/ False?
False
Usually multiple fractures or combined with joint dislocation, compared to a ‘pretzel’
Fracture of all four pubic ramii is known as a…
Straddle injury
What is the consequence of fracture of the acetabulum?
Femoral head driven through the acetabulum into the lesser pelvis
Life-threatening haemorrhage due to trauma of the bony pelvis, typically originates from which important blood vessels?
Common iliac artery
Common iliac vein
Pelvic organs are commonly damaged in bony pelvis trauma. List pelvic structures that are commonly damaged.
Pubic symphysis Uterus Sacrum Bladder Rectum Lumbosacral plexus
What are the main differences between the male and female pelvis?
AP and transverse diameters in females are greater at the pelvic inlet/ outlet
Sub-pubic angle (and pubic arch) is wider in females
Pelvic cavity is shallower in females (more spread iliac crests)
List the bones which collectively form the fetal skull
Frontal, parietal, occipital and temporal bones
State the name of the largest fontanelle present in the fetus
Anterior fontanelle
What is the anterior fontanelle?
The junction where the two frontal and two parietal bones meet
What is the posterior fontanelle?
This is the junction of the 2 parietal bones and the occipital bone
The frontal and parietal bones in the fetal skull are separated by the…
Coronal suture
The two parietal bones in the fetal skull are separated by the…
Sagittal suture
The parietal and occipital bones in the fetal skull are seperated by the…
Lamboid suture
What is the vertex?
Area of skull outlined by the anterior and posterior fontanelles and the parietal eminence
Which suture is found between the anterior and posterior fontanelles?
Sagittal suture
Explain the process of ‘moulding’ which occurs during labour to the fetal skull. What structures allow this to happen?
Movement of one bone over another to allow fetal head to pass through the pelvis during labour
Sutures and fontanelles (‘soft spots’)
The _____ diameter (length) is longer/shorter than the _____ (width) diameter in the fetal skull
The occipitofrontal diameter (length) is longer than the biparietal (width) diameter in the fetal skull
The fetus should enter the pelvic cavity facing which direction? Anatomically, how is this direction of passage encouraged?
Transverse direction (right or left)
Transverse > AP diameter at pelvic inlet
Occipitofrontal > biparietal diameter in fetal skull
What is the ‘station’ of the fetus during labour?
Distance of fetal head from ischial spines
- = superior to ischial spines
+ = inferior to ischial spines
While descending the pelvic cavity, the fetal head should undergo which movements? Anatomically, how is this direction of passage encouraged?
Rotation
Flexion (chin on chest position)
At pelvic outlet, AP > transverse diameter
At pelvic inlet, ____ is greater than ____ diameter
Transverse
AP
At pelvic outlet, ____ is greater than ____ diameter
AP
Transverse
The baby should leave the pelvic cavity in which position?
Occipitoanterior position (OA) Occipital bone of the fetal skull is anterior in the mother
During delivery, the foetal head should be in flexion/ extension.
Extension
Summarise the change in position of the fetal skull during labour from pelvic inlet to pelvic outlet
Pelvic inlet: TRANSVERSE
Pelvic cavity: ROTATION + FLEXION
Pelvic outlet: OCCIPITOANTERIOR POSITION +
EXTENSION
The ischial spines is closely associated with which spinal nerve?
Pudenal nerve (S2,3,4)
Outline the route taken by the pudenal nerve through the pelvis
Originates from S2-S4 spinal cord
Leaves the pelvis via greater sciatic foramen
Crosses sacrospinous ligament
Reenters pelvis via lesser sciatic foramen
Accompanies internal pudenal artery and vein through the pudenal canal
