Pelvis Flashcards
Has 2 coxal (hip) bones
3 parts: Ischium, ileum & pubis that join at the acetabulum of the hip joint
Bony pelvis
Transmit the dorsal primary rami of the sacral spinal nerves
Dorsal sacral foramina
Transmit the ventral primary rami of sacral spinal nerves
Ventral sacral foramina
Formed when laminae of S5 vertebra do not fuse
Sacral hiatus
Formed by pedicles
Landmarks in locating sacral hiatus for administration of caudal anesthesia
Sacral cornua
Fusion of vertebrae Co1-4
Coccyx (tailbone)
From sacrum to ischial tuberosity
Sacrotuberous ligament
From sacrum to ischial spine
Sacrospinous ligament
Divided by the PIRIFORMIS muscle into suprapiriformis recess & infrapiriformis recess
Structures transmitted:
- superior gluteal vein, artery & nerve
- Piriformis muscle
- inferior gluteal vein, artery & nerve
- sciatic nerve
- internal pudendal vein & artery
- pudendal nerve
Greater sciatic foramina
Structures transmitted:
- internal pudendal vein & artery
- pudendal nerve
The structures exit the pelvic cavity through greater sciatic foramen –> reenter the pelvic cavity through the lesser sciatic foramen –> proceed to the perineum
Lesser sciatic foramina
Defined by:
- Sacral promontory (S1)
- Linea terminalis - includes the pubic crest, iliopectineal line & arcuate line
Divides the pelvic cavity into 2 parts:
- major (false) pelvis - above the pelvic inlet between the iliac crests, part of abdominal cavity
- minor (true) pelvis - below the pelvic inlet & extends to the pelvic outlet
Measurements:
- true conjugate diameter - from sacral promontory to superior margin of pubic symphysis
- diagonal conjugate diameter - from sacral promontory to inferior margin of pubic symphysis
Pelvic inlet
Defined by coccyx, ischial tuberosities, inferior pubic ramus & pubic symphysis
Closed by the pelvic diaphragm & urogenital diaphragm
Measurements:
- Transverse diameter - distance between the ischial tuberosities
- Interspinous diameter - between ischial spines, contracted if
Pelvic outlet
Support of the pelvic organs
- Pelvic diaphragm (floor)
- Urogenital diaphragm muscle
- transverse cervical ligament (Cardinal ligament of MACKENRODT)
- uterosacral ligament
- pubocervical ligament
Coccygeus muscle & levator ani muscles (iliococcygeus, pubococcygeus & puborectalis)
Pelvic diaphragm
Forms as a U-shaped sling around the anorectal junction, causing a 90* perineal flexure; important for fecal continence
Puborectalis