The male pelvis houses the bladder, prostate, and the vascular and neural supply to the genitalia. This tab covers the bony pelvis and its ligaments, the pelvic floor, the iliac arterial tree and venous drainage, the somatic and autonomic innervation, and the rectum, pelvic ureter, and perineum.
Bony Pelvis and Ligaments
The pelvis comprises the sacrum and three innominate bones — ilium, ischium, and pubis — the ischium and pubis meeting to form the obturator foramen. Cooper's (pectineal) ligament overlies the pectineal line and anchors sutures in hernia repair and urethral suspension.
- Perineal body — a pyramidal fibromuscular hub at the central perineum into which virtually every pelvic muscle (superficial/deep transverse perinei, bulbospongiosus, levator ani, rectourethralis, external anal and striated urethral sphincters) and fascia (perineal membrane, Denonvilliers, Colles, endopelvic) inserts.
- Tendinous arch (arcus tendineus) — a thickened band of pelvic fascia from the ischial spine to the pubic bone (present in both sexes).
- Ligaments — the inguinal (ASIS → pubis); the sacrospinous (ischial spine → lateral sacrum, covered by coccygeus, with the sciatic nerve above it — at risk in vault suspension); the sacrotuberous (the two together divide the sciatic foramen into greater and lesser); and the puboprostatic ligaments (pubis → prostate/bladder neck), which support the bladder neck and mid-urethra in retropubic suspension.
Pelvic Floor Muscles
- Pelvic sidewalls — obturator internus, iliacus, psoas major and minor, the levator ani system, and coccygeus.
- Pelvic floor — the pelvic diaphragm (pubis to coccyx) and the levator ani, whose complex has three parts: pubococcygeus, puborectalis, and iliococcygeus.
Pelvic Arterial Supply
The aorta gives the middle sacral artery and the paired common iliac arteries (at L4), which bifurcate at the SI joint into the external and internal iliac arteries.
External iliac artery — follows the medial iliopsoas and becomes the femoral artery beneath the inguinal ligament. It is the only pelvic vessel without adequate collateral (ligation causes significant sequelae). Its branch, the inferior epigastric artery, ascends medial to the internal ring (within the lateral umbilical fold) and forms the lateral border of Hesselbach's triangle (lateral: inferior epigastric vessels; medial: rectus abdominis; inferior: inguinal ligament). It gives the deep circumflex iliac, pubic, and cremasteric branches; in ~25% an accessory obturator artery arises from it (avoid in obturator node dissection).
Internal iliac (hypogastric) artery — divides into posterior and anterior trunks ~3–4 cm from the bifurcation.
- Posterior trunk (S-GALLS) — Superior Gluteal, Ascending Lumbar (iliolumbar), and Lateral Sacral arteries; rarely encountered in pelvic surgery.
- Anterior trunk — its surgically important branches are the superior vesical, uterine, and occasionally obturator arteries:
- Umbilical — its proximal part remains as the first anterior-trunk branch; the obliterated umbilical artery lies lateral to the ureter at the pelvic brim and gives rise to the superior vesical.
- Superior vesical — the most prominent branch; its artery of the vas anastomoses distally with the cremasteric and testicular arteries (so the testicular artery can be sacrificed without losing the testis).
- Obturator — runs through the obturator fossa medial and posterior to the obturator nerve.
- Inferior vesical — supplies the bladder base, seminal vesicle, prostate, lower ureter, and neurovascular bundle.
- Middle rectal — small branches to the seminal vesicles and prostate.
- Internal pudendal — the terminal branch; it exits the greater sciatic foramen, hooks around the sacrospinous ligament, and runs in Alcock's (pudendal) canal on the obturator internus. Its branches (IPP-BC) are the Inferior rectal, Perineal, Posterior scrotal, artery of the Bulb, and Common penile (→ cavernosal, bulbourethral, and dorsal arteries).
- Inferior gluteal (and, in women, the vaginal and uterine arteries — the uterine passing anterior to the ureter).
(Note the external pudendal arises from the femoral artery and the superior rectal from the IMA.)
Pelvic Venous Drainage
The internal iliac vein ascends medial and posterior to its artery and is thin-walled — at risk during arterial or ureteric dissection. The external iliac vein continues from the femoral vein and receives the inferior epigastric, deep circumflex iliac, and pubic veins; in ~50%, accessory obturator veins drain into its underside and are easily torn during lymphadenectomy.
Pelvic Innervation
| Nerve | Origin | Motor | Sensory |
|---|---|---|---|
| Iliohypogastric | L1 | Internal oblique, transversus | Lower anterior abdominal wall |
| Ilioinguinal | L1 | — | Anterior scrotum, root of penis, upper medial thigh |
| Genitofemoral | L1–L2 | Genital branch: cremaster | Genital: anterior scrotum; femoral: upper anterior thigh |
| Lateral femoral cutaneous | L2–L3 | — | Anterior and lateral thigh |
| Femoral | L2–L4 | Knee extensors | Anterior thigh, medial leg |
| Obturator | L2–L4 | Thigh adductors | Medial thigh |
| Posterior femoral cutaneous | S2–S3 | — | Perineum, posterior scrotum, posterior thigh |
| Pudendal | S2–S4 | Levator ani, urogenital diaphragm, anal & striated urethral sphincter | Perineum, scrotum, penis |
| Nervi erigentes | S2–S4 | Parasympathetic to pelvic viscera | — |
- Surgical pearls: the ilioinguinal nerve (outside and anterior to the cord) can be injured at orchiectomy; the genitofemoral nerve (genital branch travels in the cord) is at risk in psoas hitch and laparoscopic varicocelectomy; the femoral nerve runs within the psoas (compressed by retractor blades or stretched in lithotomy — place psoas-hitch sutures parallel to its fibres); and the obturator nerve can be stimulated by cautery during TURBT, causing a thigh jerk and bladder perforation. Exaggerated lithotomy can stretch the lumbosacral trunk or compress the peroneal branch at the fibular head (foot drop).
- The pudendal nerve follows the internal pudendal artery into the perineum and branches into the dorsal nerve of the penis (first branch), inferior rectal, and perineal nerves.
- Autonomic — the pelvic (inferior hypogastric) plexus receives sympathetic fibres (via the superior hypogastric plexus/hypogastric nerve from T10–L2 and the sacral sympathetic trunk) and parasympathetic fibres (S2–S4 pelvic splanchnics/nervi erigentes). Its midpoint lies at the tips of the seminal vesicles. Clinical: dividing the lateral pedicles proximally transects both vessels and the nerves to the prostate, urethra, and corpora (impotence) — ligate near the bladder; during radical prostatectomy the nerves are most vulnerable at the apex (5 and 7 o'clock).
Rectum and Pelvic Ureter
- Rectum — peritoneum covers the upper two-thirds as the rectovesical pouch; below it the anterior rectum relates to Denonvilliers' fascia down to the striated sphincter, and anterior colonic longitudinal fibres join the external sphincter as the rectourethralis. Blood supply: superior rectal (IMA), middle rectal (internal iliac), inferior rectal (internal pudendal).
- Pelvic ureter — found anterior to the common iliac bifurcation; the two ureters come within 5 cm of each other crossing the iliac vessels, then diverge toward the ischial spines and turn medially to the bladder. The vas deferens crosses anterior to it. To reach the distal ureter in women, five structures are divided: the round ligament, obliterated umbilical artery, uterine artery, and superior and inferior vesical arteries.
Perineum
The diamond-shaped perineum is divided by a line through the ischial tuberosities into anal and urogenital triangles. The perineal membrane (formerly the urogenital diaphragm) divides the urogenital hiatus into superficial and deep perineal spaces. In the superficial pouch, the three erectile bodies form the root of the penis: the paired corpora cavernosa attach to the ischiopubic rami (surrounded by ischiocavernosus), and the corpus spongiosum dilates as the bulb fixed to the perineal membrane (surrounded by bulbospongiosus) — contraction of both potentiates erection. Perineal lymphatics drain to the inguinal nodes: scrotal lymphatics do not cross the median raphe (ipsilateral superficial nodes only), whereas penile lymphatics can cross to both superficial and deep nodes.