Pelvis Flashcards
Has 2 coxal (hip) bones
3 parts: Ischium, ileum & pubis that join at the acetabulum of the hip joint
Bony pelvis
Fusion of S1-5
Sacrum
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
Deep transverse perineal muscle
Sphincter urethra muscle
Urogenital diaphragm muscle
Thickening of the endopelvic fascia
Laterally from cervix to the sidewall of the pelvis
Transverse cervical ligament (Cardinal ligament of MACKENRODT)
From cervix to the sacrum
Uterosacral ligament
From cervix to pubic symphysis
Pubocervical ligament
Weakening of support of pelvic organs
- cystocele
- Rectocele
- uterine prolapse
- risk factors: multiparity, birth trauma, ⬆️ intraabdominal pressure from obesity, heavy lifting, chronic cough, menopausal loss of muscle tone
- SSX: heavy sensation in the lower abdomen, aggravated by heavy lifting, prolonged standing; urinary frequency/stress incontinence (leakage with coughing or sneezing)
Pelvic relaxation
1% lidocaine solution injected transvaginally or just lateral to the labia majora around the tip of ischial spine & through the sacrospinous ligament
Pain of Childbirth is transmitted by pudendal nerve via spinal nerves S2-5
Pudendal nerve block
Course of pudendal nerve
Exits the pelvic cavity through greater sciatic foramen
Travel around the posterior surface of ischial spine
Renters pelvic cavity through lesser sciatic foramen
Travels within the fascia of obturator internus muscle (pudendal nerve of Alcock) & divides into:
- perineal nerve
- posterior labial nerve
- inferior rectal nerve
- dorsal nerve of the clitoris
To obtain complete anesthesia of perineal region, the ff nerves must also be anesthesized:
Ilioinguinal nerve
Genitofemoral nerve
Perineal branch of posterior femoral cutaneous nerve
Basin and is more correctly applied to the skeleton of the region
Region of the trunk below the abdomen and meets the lower extremity
PELVIS
Surface landmarks
Iliac crest
Anterior superior iliac spine
Pubic tubercle - bony projection at the superior lateral border of the body of pubic bone
Symphysis pubis
Posterior superior iliac crest
MUST KNOW: 1. Brim Ant - symphysis pubis Lat - iliopectineal line Post - sacral promontory
- Above
False pelvis
Greater pelvis
Pelvis major - Below
True pelvis
Lesser oelvis
Pelvis minor - Pelvic inlet
Ant - symphysis pubis
Lat - iliopectineal line
Post - sacral promontory - Pelvic outlet
Ant - pubic arch
Lat - ischial tuberosities
Post - tip of coccyx
Must know!!
