10. Pelvis I Flashcards
Pelvic Girdle
Os coxae (hip bones)
Sacrum
Coccyx
Bony Pelvis
Connects thoracic cavity to LE
Consists of 4 bones
Os Coxae
Ilium
Ischium
Pubis
Acetabulum
Fusion of ilium, ischium, pubis
Fuses at about age 16
Head of femur articulates here, forming hip joint
Obturator Foramen
Ischium + pubis
Ilium
Iliac crest (connects ASIS to PSIS)
Iliac fossa (concave medial surface)(iliacus sits here)
ASIS
PSIS
Pubis
Pubic tubercle
Pubic symphysis
Pubic Symphysis
Pubic bones articulate at midline to form
Fibrocartilaginous joint (not much movement)
Ligaments relax right before birth
Pubis + Ischium
Superior pubic ramus (unites ilium and ischium superiorly)
Inferior pubic ramus
Ischial ramus
Isciopubic ramus
Isciopubic Ramus
Inferior pubic ramus + ischial ramus
Ischium
Greater sciatic notch
Ischial spine
Lesser sciatic notch
Ischial tuberosity (muscle attachment)
Pubic Arch
2 ischiopubic rami
Inferior borders define subpubic angle
Sacrum
5 fused vertebrae
Base (articulates with L5/S1 intervertebral disc and L5 vertebra)
Apex (articulates with coccyx)(S5)
Sacroiliac joints
Sacral promontory
Sacral foramina
Sacral Promontory
Anterior edge of S1 projection
Obstetrical landmark
Sacral Foramina
4 pair anterior
4 pairs posterior
For transmission of ventral and dorsal rami of sacral spinal nerves
Coccyx
4 fused vertebrae
Articulates with sacrum at sacrococcygeal joint
Pelvic Inlet
Divides pelvis into greater and lesser pelvis
Normally tilted about 55 degrees from horizontal plane (tipped in anatomic position)
Greater (False) Pelvis
Superior to pelvic inlet
Occupied by abdominal viscera
Between ilium
Lesser (True) Pelvis
Inferior to pelvic inlet
Occupied by pelvic viscera
Very small region
Pelvic Outlet
Boundaries:
- coccyx and sacrum
- sacrotuberous ligaments
- ischial tuberosities
- ischiopubic rami (pubic arch)
- pubic symphysis
Normally tilted at 15 degrees from horizontal plane (tipped in anatomic position)
Pelvic Diaphragm
Muscle separating pelvis above from perineum below
Closes up pelvic outlet
Sex Differences in Pelvis
Pelvis inlet:
- F: larger, round/oval
- M: heart shaped, narrower anteriorly
Pelvic outlet:
-F: ischial tuberosities and ischial spines more laterally displaced (for babies)
Subpubic angle
- F: wider (>80)
- M: narrower (<70)
Sacroiliac Ligaments
Anterior
Posterior
Interosseus
Ligaments relax for baby time
Sacrotuberous Ligament
Sacrum/coccyx to ischial tuberosity
Sacrospinous Ligament
Sacrum/coccyx to ischial spine
Axis of Rotation
Sacrotuberous and sacrospinous ligaments resist the influence of body weight that rotates the sacrum and coccyx posteriorly and superiorly
Greater Sciatic Foramen
Superior to ischial spine
Passageway to/from gluteal region
Lesser Sciatic Foramen
Inferior to ischial spine
Passageway to/from perineum
Obturator Membrane
Closes obturator foramen except obturator canal
Obturator Canal
Passageway to medial compartment of thigh
Conveys neurovascular structures (obturator nerve)
Muscles of Lesser Pelvis: Piriformis
Posterior wall of lesser pelvis
Origin: ant surface of sacrum
Courses through greater sciatic foramen
Insertion: femur
Innervation: sacral plexus
Muscles of Lesser Pelvis: Obturator Internus
Lateral walls of lesser pelvis
Origin: obturator membrane and margin of obturator foramen
Courses through lesser sciatic foramen
Insertion: femur
Innervation: sacral plexus
Covered on medial surface by thick obturator fascia (attachment for muscles of pelvic diaphragm)
Muscles of Lesser Pelvis: Pelvic Diaphragm
Bowl/funnel shaped
R and L fuse in midline to form median raphe
Closes inferior pelvic aperture/pelvic outlet and forms pelvic floor
Supports pelvic viscera superiorly, perineum lies inferior
Pelvic structures pass through to reach perineum (urethra, vagina, rectum)
Innervation: branches of sacral and coccygeal plexuses
Tendinous Arch of Levator Ani
Obturator fascia thickens centrally as tendinous arch for attachment of levator ani
Ends at ischial spine
Pelvic Diaphragm: Composed of 2 Muscles
Levator Ani
Coccygeus
Coccygeus
Extends from ischial spine to coccyx/inf sacrum
Lies on internal surface of sacrospinous ligament
Levator Ani
Extends from pubis/ischial spine to coccyx/median raphe
Levator Ani: Openings
Posterior: anal aperture
Anterior: urogenital hiatus (passageway for urethra)(F: also vagina, vaginal canal)
Ant urethra vagina rectum Post
Levator Ani: Portions
Pubococcygeus
Iliococcygeus
Pubococcygeus
Fibers wrap around pelvic viscera
Muscular slings = support
Pubovaginalis (F)
Puboprostatiucs (M)
Puborectalis
Puborectalis
Sling around anorectal junction
Maintains anorectal flexure
Relaxes during defecation - rest of levator ani/pelvic diaphragm contracts to prevent viscera from herniating
Pelvic Diaphragm: Weakness
Urinary stress incontinence
Bowel incontinence
Prolapse of pelvic viscera
Pelvic Arteries
Gonadal (ovarian/testicular)
Abdominal aorta
Common iliac
External iliac
Internal iliac
Gonadal Arteries
Branches of ab aorta
Testicular: travel within spermatic cords inf
Ovarian: travel within suspensory ligaments of ovaries
-supply gonads, uterine tubes, uterus
Common Iliac Arteries
Divide into external and internal iliac arteries
External Iliac Artery
Supplies anterolateral ab wall and LE
Internal Iliac Artery
Primary blood supply to pelvis, perineum, gluteal region
Internal Iliac Artery: Branches
Superior gluteal artery Inferior gluteal artery Internal pudendal artery Umbilical artery Obturator artery *Aberrant obturator artery* Superior vesicle artery Inferior vesical artery Uterine artery (F) Vaginal artery (F) Middle rectal artery
Superior Gluteal Artery
Exits greater sciatic foramen
Superior to piriformis to supply gluteal region
Inferior Gluteal Artery
Exits greater sciatic foramen
Inferior to piriformis to supply gluteal region
Internal Pudendal Artery
Makes a U turn - exits greater sciatic foramen
Travels to perineum via lesser sciatic foramen
Supplies structures of perineum
Gives rise to inferior rectal artery (supplies anal canal)
Umbilical Artery
Gives rise to superior vesical artery supplying superior aspect of bladder (and ductus deferens in M)
Obliterated portion continues on as medial umbilical ligaments
Obturator Artery
Courses along lateral wall of pelvis with obturator vein and nerve
Exits pelvis via obturator canal to enter medial compartment of thigh
Aberrant Obturator Artery
20% of population
Arises from inferior epigastric artery (branch of external iliac)
Courses over superior pubic ramus to exit via obturator canal
Can be accidentally damaged during inguinal hernia repairs
Inferior Vesical Artery
Direct branch of internal iliac (M)
Supplies inferior bladder, urethra, seminal vesicle, prostate
Uterine Artery
F
Passes superior to ureter
Vaginal Artery
F
Supplies vagina, inf bladder (via inferior vesical branch), urethra
Anastomoses with uterine arteries which anastomose with ovarian arteries
Middle Rectal Artery
Emerges off pudendal
Anastomoses with superior and inferior rectal arteries (branch of IMA)
Pelvic Veins
Similar to arterial pattern (share names)
Venous Plexuses
Prostatic Uterine Vaginal Vesical Rectal
Pelvic Lymphatics
Internal iliac nodes –> common iliac nodes –> lumbar nodes –> chyle cistern –> thoracic duct
Gonadal Lymphatics
Ovaries, testes –> lumbar nodes –> chyle cistern –> thoracic duct
