1: Anatomy - Bony pelvis, pelvic fracture and labour Flashcards
What is another name for the hip bone?
Innominate bone
What are the three parts of each innominate bone?
Ilium
Ischium
Pubic bone
At which joints do the innominate bones
a) connect anteriorly
b) connect to the sacrum posteriorly?
a) Pubic symphysis
b) Sacroiliac joints
At which level does the dura end?
S2
Spinal cord ends at L2 (conus medullaris) but dura continues with the cauda equina
What spinal level is the transtubercular plane found at?
L5
Why is the ischial spine an important feature?
Sacrospinous ligament attaches to it
And the pudendal nerve traverses around the sacrospinous ligament
Which nerve twists around the sacrospinous ligament?
Pudendal nerve (S2-4)
Which muscle group attaches to the ischial tuberosity posteriorly?
Hamstrings group
Medial to lateral: semimembranosus, semitendinosus, biceps femoris
What happens to the sacrospinous and sacrotuberous ligaments during pregnancy?
Relaxation
Which bony feature of the ischium forms the inferior border of the obturator foramen?
Ischiopubic ramus
How does the pubic arch differ in appearance in males versus females?
Males - smaller angle (**/** shape)
Females - greater angle, wider pelvic inlet/outlet for childbirth
Where does the pelvis tend to fracture?
Multiple places
bony ring
Pelvic fractures often occur alongside joint ___.
dislocations
Which neurovascular structures may be disrupted by pelvic trauma?
Common iliac artery
Common iliac vein
Sacral plexus
Why is pelvic haemorrhage so dangerous?
Internal bleeding
Occurs without visible signs until life-threatening
What are the structural differences between the male and female pelvis?
In females:
deeper pubic arch
greater AP and transverse diameters of pelvic inlet and outlet
shallower pelvic cavity
compared to men
How many frontal bones does the foetal skull have?
Two
Which structures allow the bones of the foetal skull to move and slide over one another during childbirth?
Anterior and posterior fontanelles
When may the anterior and posterior fontanelles be
a) bulging
b) depressed?
a) Increased intracranial pressure (e.g hydrocephalus)
b) Malnutrition / dehydration
What are the three sutures found in the foetal skull?
Sagittal suture
Coronal suture
Lambdoid suture
What area is found within the borders made by the anterior and posterior fontanelles and the parietal prominences?
Vertex
In the context of childbirth, what is moulding?
Sliding of skull bones over one another
Reduces diameter of foetal head during childbirth
Which bony features form the pelvic inlet?
Sacral promontory
Ilium
Superior pubic ramus
Pubic symphysis
Which bony features form the pelvic outlet?
Pubic symphysis
Ischiopubic ramus
Ischial tuberosities
Sacrotuberous ligaments
Coccyx
The foetal head has frontotemporal (front to back) and biparietal (side to side) diameters.
Which diameter is greater?
Frontotemporal diameter > Biparietal diameter
i.e a newborn’s head should be longer than it is wide
What ligaments form the
a) greater
b) lesser sciatic foramen?
a) GREATER SCIATIC FORAMEN - both
b) LESSER SCIATIC FORAMEN - both
