ANHB2212 Lecture Notes - Lecture 15: Iliopubic Eminence, Pelvic Brim, Pelvic Inlet
25 May 2018
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Pelvis:
4 main functions:
1 – girdle for attachment of the lower limbs - SCAFFOLD
2 – route for transmitting vessels, nerves etc to and from trunk and lower limbs – FUNNEL
3 – container for pelvic organs (which, in females must be large enough to hold baby) – BOWL
4 – means of controlling passage of objects/materials between interior of body and environment
(urine, faeces, menstrual blood, penises, semen, baby,) –
DIAPHRAGM
Components:
Sacrum and 2 hip bones and coccyx.
- Each hip bone composed of 3 bones which fuse during childhood
- ilium, ischium, pubis.
False pelvis – part that is above pelvic brim
- Iliac blades and crests
- Abdominal aspect
- Gluteal aspect
True Pelvis – part below pelvic brim
- Walls of pelvic cavity
- Mainly pubis and ischium
Pelvic inlet:
- Promontory of the sacrum
- Alae of sacrum
- Iliopectineal line – arcuate line
- iliopubic eminence
- pectin pubis
- Pubic crest
- Symphysis pubis
Pelvic outlet: inferior opening
- Ischial tuberosities
- Ischiopubic rami
- Sacrotuberous ligaments
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Female inlet and outlet diameters:
Important for birthing process
Conjugate diameters
- Between symphysis and sacral
promontory = 11cm
Transverse diameters
- Midpoint of brim on each side =
13cm
Oblique diameters
- Iliopubic eminence to sacroiliac joint
= 17.5cm
Joints of pelvis:
All reinforced by lashings of ligaments
- Sacrotuberous ligament
- Sacrospinous ligament
- Iliolumbar ligament
Pubic Symphysis:
Bone → hyaline cartilage → fibrocartilage →hyaline cartilage → bone
AMPHIARTHROSIS
Reinforced by superior pubic ligament and arcuate ligament
Rare to become fused
- often develops joint cavity in women after childbirth
- similar to formation of uncoveretebral joints by fissuring of fibrocartilage disc.
Sacroiliac Joint:
Joins auricular surfaces of ilium and sacrum.
SYNOVIAL
Strong dorsal ligament
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Fibrous capsule attaches around margins of joint
- thin anteriorly / ventral sacroiliac ligament
- thick posteriorly / dorsal interosseous
sacroiliac ligament
dorsal interosseous sacroiliac ligament
attaches to large rough areas behind auricular
surfaces of sacrum and ilium.
Auricular surface of ilium:
Not flat – irregular elevations
- vary with age and strains on
interosseous sacroiliac ligament (used in
forensics)
- limit amount of movement and promote transfer of weight from vertebral column to limbs.
Pelvic instability:
Lumbosacral spondylolisthesis:
Upper surface of sacrum is steep (60 degrees)
Strong tendency for lumbar vertebrae to slide forwards
Resistance to sacroiliac slip:
Lumbosacral disc.
Iliolumbar ligament:
- attaches to L5 transverse processes (large and
strong) to iliac crest
articular processes
- interlock to prevent anterior slippage of the L5
- in 9% of people there is weakness of the pars
interarticularis of the lumbar vertebrae which –
connects the inferior articular processes and
spinous processes to the superior articular
processes and the vertebral body.
- Articular procecces cant support L5/S1 disc –
spondylolisthesis
find more resources at oneclass.com
find more resources at oneclass.com
