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Home , Iliolumbar vein, Inferior rectal veins, Internal iliac vein, Median sacral artery, Superior gluteal artery, Vesical veins

DR MOUIN ABBOUD PR OF ANATOMY In faculity of medecin ( Damascus and Sham uneversities ) Specialist in respiratory diseases

الدكتور معين عبود استاذ التشريح في كلية الطب البشري في جامعة دمشق وجامعة الشام الخاصة اختصاصي في أمراض جهاز التنفس DR MOUIN ABBOUD

– blood vessels - nerves Major of the Pelvis

 Arteries of the Pelvis are :  The internal iliac : The major artery of the pelvis and perineum  Other vessels that originate in the and contribute to the supply of pelvic structures include:  the  and, in women, the ovarian arteries. It originates at the bifurcation of the common iliac

Internal iliac artery

 The originates from the on each side, approximately at the level of the intervertebral disc between LV and SI and lies anteromedial to the sacro-iliac joint  The vessel courses inferiorly over the pelvic inlet, then divides into anterior and posterior trunks at the level of the superior border of the greater sciatic foramen. Branches from the posterior trunk contribute to the supply of the lower posterior abdominal wall, the posterior pelvic wall, and the gluteal region. Branches from the anterior trunk supply the pelvic viscera, the perineum, the gluteal region, the adductor region of the thigh, and, in the fetus, the placenta.

Anterior Trunk

 The anterior trunk gives rise to numerous branches that supply the pelvic organs, the perineum, and the gluteal and adductor regions of the lower limb.  working anti-clockwise from to .

– Gives rise in (male) –  the superior vesical artery  Inferior vesical artery  –  The obturator artery   Inferior gluteal artery –  The uterine artery

Obturator artery

 Obturator artery – Travels through the obturator canal, accompanied by the obturator nerve and .  It supplies the muscles of the thigh’s adductor region. Umbilical artery

 Umbilical artery – Gives rise to the superior vesical artery, which supplies the superior aspect of the .  The umbilical artery also transports blood from the placenta to the fetus during gestation.  After birth, it closes distally to the origin of the superior vesical artery, and forms the medial umbilical ligament. Inferior vesical and

 Inferior vesical artery (male) – Supplies the gland, seminal vesicle and inferior aspect of the bladder.  the equivalent artery in women is the vaginal artery. supplies branches to the and to adjacent parts of the bladder and . Uterine artery

 Uterine artery (female) Travels within the broad ligament to reach the cervix, where it ascends along the lateral aspect of the uterus.  At origin of the fallopian tubes, it anastamoses with the ovarian artery.  During its course, it crosses the superiorly.

Middle rectal artery

 Middle rectal artery : Travels medially to supply the distal part of the rectum.  It also forms anastamoses with the superior rectal artery (derived from the inferior mesenteric) and the inferior rectal artery (derived from the internal pudendal)

Internal pudendal artery

 Internal pudendal artery – Moves inferiorly to exit the pelvis via the greater sciatic foramen inferior to the .  Accompanied by the pudendal nerve, it then enters the perineum via the lesser sciatic foramen.  It is the main artery responsible for the blood supply to the perineum..

Inferior gluteal artery

 Inferior gluteal artery – The terminal branch of the anterior trunk.  It leaves the via the greater sciatic foramen, emerging inferiorly to the piriformis muscle in the gluteal region.  It contributes to the blood supply of the and joint.

Posterior Trunk

 The posterior trunk gives rise to arteries that supply the lower posterior abdominal wall, posterior pelvic wall and the gluteal region.  There are typically three branches:  –  Lateral sacral arteries (superior and inferior) –  –

Iliolumbar artery

 Iliolumbar artery – Ascends to exit the lesser pelvis, dividing into a lumbar and iliac branch.  The lumbar branch contributes to the supply of the posterior abdominal wall, psoas, quadratus lumborum muscles, and cauda equina via a small spinal branch that passes through the intervertebral foramen between LV and SI.  The iliac branch passes laterally into the iliac fossa to supply muscle and bone.

Lateral sacral arteries

 Lateral sacral arteries (superior and inferior) – Travel infero- medially along the posterior pelvic wall to supply structures in the sacral canal, and the skin and muscle posterior to the .

Superior gluteal artery

 Superior gluteal artery – The terminal branch of the posterior trunk.  It exits the pelvic cavity via the greater sciatic foramen, entering the gluteal region superiorly to the piriformis muscle.  It is the major blood supply to the muscles and skin of the gluteal region.

Minor Arteries of the Pelvis

 Gonadal Arteries  Median Sacral Artery  Superior Rectal Artery Gonadal Arteries

 Gonadal Arteries  The ovarian artery is the major in females. It arises from the abdominal , distal to the origin of the renal arteries. The artery descends towards the pelvis, crossing the and the origin of the external iliac vessels. It moves medially, dividing into an ovarian branch and tubal branches, which supply their respective structures.  Note – the reaches the scrotum via the inguinal canal, and therefore does not actually enter the pelvis. Median Sacral Artery

 Median Sacral Artery  The median sacral artery originates from the posterior aspect of , at its bifurcation into the common iliac arteries.  It descends anteriorly to the L4 and L5 vertebrae, the sacrum and the , contributing to the arterial supply of these regions.

Superior Rectal Artery

 Superior Rectal Artery  The superior rectal artery is the terminal continuation of the inferior mesenteric artery.  It crosses the left common iliac artery and descends in the mesentery of the sigmoid colon.  It gives rise to branches that supply the rectum.

Venous Drainage of the Pelvis

 Venous Drainage of the Pelvis–  the external ,   and  median sacral  Ovarians veins

External Iliac Vein

 The is a continuation of the femoral vein  It ascends along the medial aspect of the external iliac artery, before joining with the internal iliac vein to form the common iliac vein.  During its short course, the external iliac vein receives the inferior epigastric and deep circumflex iliac veins.

Internal Iliac Vein

 Pelvic veins follow the course of all branches of the internal iliac artery except for :  the umbilical artery  and the iliolumbar artery  It is formed near the greater sciatic foramen, ascending anteriorly to the , before combining with the external iliac vein to form the common iliac vein.  With the exception of the (which drains into the common iliac), The tributaries of the internal iliac vein

 the tributaries of the internal iliac vein correspond with the branches of the internal iliac artery :  Superior and inferior gluteal veins – drains the buttock and upper thigh.  Internal pudendal vein – drains the reproductive organs and part of the rectum (via the inferior rectal vein).  Obturator vein  Lateral sacral veins – drains part of the sacrum.  Middle rectal vein – drains the bladder, prostate (in males only), and part of the rectum.  – drains the urinary bladder via the vesical .  Uterine and vaginal veins – drain the female reproductive organs via the vaginal and uterine venous plexuses. pelvic plexus

 Within the pelvic cavity, extensive interconnected venous plexuses are associated with the surfaces of the viscera (bladder, rectum, prostate, uterus, and vagina).  Together, these plexuses form the pelvic plexus of veins Portacaval -rectum

 The part of the venous plexus surrounding the rectum and drains via superior rectal veins (tributaries of inferior mesenteric veins) into the , and via middle and into the caval system. This pelvic plexus is an important portacaval shunt when the hepatic portal system is blocked Common Iliac Vein

 The common iliac vein is formed at the upper margin of the pubic symphysis by the union of the external and internal iliac veins. It receives two additional tributaries:  Iliolumbar vein – drains the L4 and L5 vertebrae, and the iliopsoas muscle.  Middle sacral veins – drain part of the sacrum.  The left and right common iliac veins combine at L5 to become the inferior vena cava, which empties into the inferior aspect of the right atrium. the median sacral veins

 the median sacral veins coalesce to form a single vein that joins either the left common iliac vein or the junction of the two common iliac veins to form the inferior vena cava; the ovarian veins

 the ovarian veins follow the course of the corresponding arteries; on the left, they join the left and, on the right, they join the inferior vena cava in the abdomen.

Nerves

 Somatic plexuses  Sacral  and coccygeal plexuses  Visceral plexuses :  Paravertebral sympathetic chain  Parasympathetic fibers Somatic plexuses The somatic plexuses are : Sacral and coccygeal plexuses

 The plexus is formed in relation to the anterior surface of the piriformis muscle,  The sacral plexus on each side is formed by the anterior rami of S1 to S4, and the lumbosacral trunk (L4 and L5)  Gray rami communicantes from ganglia of the sympathetic trunk connect with each of the anterior rami  In addition, special visceral nerves (pelvic splanchnic nerves) originating from S2 to S4 deliver preganglionic parasympathetic fibers to the pelvic part of the prevertebral plexus  Each anterior ramus has ventral and dorsal divisions  The anterior ramus of S4 has only a ventral division.

Branches of the sacral plexus

 Branches of the sacral plexus include  the and gluteal nerves, which are major nerves of the lower limb,  and the pudendal nerve, which is the nerve of the perineum  Numerous smaller branches supply the pelvic wall, floor, and lower limb.

 Most nerves originating from the sacral plexus leave the pelvic cavity by passing through the greater sciatic foramen inferior to piriformis muscle, and enter the gluteal region of the lower limb.  Other nerves leave the pelvic cavity using different routes;  a few nerves do not leave the pelvic cavity and course directly into the muscles in the pelvic cavity.  Finally, two nerves that leave the pelvic cavity through the greater sciatic foramen loop around the ischial spine and sacrospinous ligament and pass medially through the lesser sciatic foramen to supply structures in the perineum and lateral pelvic wall. Coccygeal plexus

 The small coccygeal plexus has a minor contribution from S4 and is formed mainly by the anterior rami of S5 and Co, which originate inferiorly to the pelvic floor.  They penetrate the coccygeus muscle to enter the pelvic cavity and join with the anterior ramus of S4 to form a single trunk, from which small anococcygeal nerves originate  These nerves penetrate the muscle and the overlying sacrospinous and sacrotuberous ligaments and pass superficially to innervate skin in the anal triangle of the perineum. Visceral plexuses

 Paravertebral sympathetic chain  Pelvic extensions of the prevertebral plexus The prevertebral plexus

 The three major divisions of the abdominal prevertebral plexus and associated ganglia are  the celiac :  two celiac ganglia,  a single superior mesenteric ganglion,  and two aorticorenal ganglia  Aortic : the major ganglion in this plexus is the inferior mesenteric ganglion :  and superior hypogastric plexuses : contains numerous small ganglia and is the final part of the abdominal prevertebral plexus before the prevertebral plexus continues into the pelvic cavity.

Paravertebral sympathetic chain

 The sacral sympathetic trunk crosses the pelvic brim behind the common iliac vessels.  There are four ganglia along each trunk which unite in front of the coccyx at the ganglion impar.  The sacral sympathetic trunk gives  somatic branches to all the sacral nerves for distribution to the periphery, mainly to parts of the lower limb and perineum )gray rami communicantes (  In addition to gray rami communicantes, other branches (the sacral splanchnic nerves) join and contribute to the pelvic part of the prevertebral plexus associated with innervating pelvic viscera.

Pelvic extensions of the prevertebral plexus

 The pelvic parts of the prevertebral plexus carry sympathetic, parasympathetic, and visceral afferent fibers to inferior hypogastric plexuses  Pelvic parts of the plexus are associated with innervating pelvic viscera and erectile tissues of the perineum.

Inferior hypogastric plexuses

 The prevertebral plexus enters the pelvis as two hypogastric nerves, one on each side, formed by the separation of the fibers in the superior hypogastric plexus, into right and left bundles.  When the hypogastric nerves are joined by pelvic splanchnic nerves carrying preganglionic parasympathetic fibers from S2 to S4, the pelvic plexuses (inferior hypogastric plexuses) are formed

Branches of inferior hypogastric plexuses

 The inferior hypogastric plexuses, one on each side, course in an inferior direction around the pelvic walls, medially to major vessels and somatic nerves.  They give origin to the following subsidiary plexuses, which innervate the pelvic viscera:  the rectal plexus;  the uterovaginal plexus;  the prostatic plexus; and  the vesical plexus.  Terminal branches of the inferior hypogastric plexuses penetrate and pass through the deep perineal pouch and innervate erectile tissues of the penis and the clitoris in the perineum

Sympathetic fibers - functions

 Sympathetic fibers - functions :  innervate blood vessels;  cause contraction of smooth muscle in :  the internal urethral sphincter in men  and the internal anal sphincters in both men and women  cause smooth muscle contraction associated with:  the reproductive tract  and with the accessory glands of the reproductive system  and are important in moving secretions from the epididymis and associated glands into the to form semen during ejaculation.

Parasympathetic fibers

 Parasympathetic fibers enter the pelvic plexus in pelvic splanchnic nerves that originate from spinal cord levels S2 to S4  They:  are generally vasodilatory;  stimulate bladder contraction;  stimulate erection;  and modulate activity of the enteric nervous system of the colon distal to the left colic flexure (in addition to pelvic viscera, some of the fibers from the pelvic plexus course superiorly in the prevertebral plexus, or as separate nerves, and pass into the inferior mesenteric plexus of the abdomen).

Visceral afferent fibers

 Visceral afferent fibers follow the course of the sympathetic and parasympathetic fibers to the spinal cord.  Afferent fibers that enter the cord in lower thoracic levels and lumbar levels with sympathetic fibers generally carry pain;  however, pain fibers from the cervix and some pain fibers from the bladder and urethra may accompany parasympathetic nerves to sacral levels of the spinal cord.