The bony pelvis.
- Ishial tuberoscity
- Greater and lesser sciatic notch
- Obturator foramen
- Ischial spine
- ASIS, AIIS
- Tubercle, crest, superior and inferior rami
Structures palpable on PR examination
- POD in women
- Prostate in men
Blood supply / venous drainage of the rectum / anus.
- Superior rectal artery – from inferior mesenteric
- Middle rectal artery – from inferior vesicle artery
- Inferior rectal artery – from internal pudendal artery – supply external anal sphincter, anorectal junction and anal canal.
- Superior, middle and inferior rectal vein, internal and external rectal venous plexuses.
- Superior drains into portal while other 2 drain into systemic veins
Lymphatic drainage of the rectum / anus.
- Superior half drain to pararectal LNs–> inferior mesenteric LNs–> drain to Lumbar(caval/aortic) LNs
- Inferior half–>sacral LNs–> internal iliac LNs
The bladder / Control of micturition.
- Sympathetics – relax detrusors and constrict urethral sphincter
- Inferior thoracic and upper lumbar cord levels –> hypogastric plexus –> vesicle plexus
- Parasympathetic – contract detrusors and relax urethral sphincter
- Sacral spinal cord segments –> pelvic splanchnic nerves and inferior hypogastric plexus
- Sensory afferents follow parasympathetic fibres
The male urethra.
- 18-22cm long
- Four parts
- Intramural 0.5-1.5cm
- Prostatic 3-4cm widest
- Membranous 1-1.5cm narrowest
- Spongy 15cm
- The sacroiliac joint or SI joint (SIJ) is the joint in the bony pelvis between the sacrum and the ilium of the pelvis.
- Joined by strong ligaments.
- Sacrum supports the spine and is supported in turn by an ilium on each side.
- The joint is a strong, weight bearing synovial plane joint with irregular elevations and depressions that produce interlocking of the two bones.