Pelvic Nerves & Vessels
Pelvis & Perineum Unit Lecture 5 د. حيدر جليل الأعسم
Pelvic Nerves Sacral Plexus Sacral plexus lies on posterior pelvic wall in front of piriformis muscle. It is formed from anterior rami of 4th & 5th lumbar nerves and anterior rami of 1st, 2nd, 3rd & 4th sacral nerves. The 4th lumbar nerve joins the 5th lumbar nerve to form lumbosacral trunk. Lumbosacral trunk passes down into pelvis and joins sacral nerves as they emerge from anterior sacral foramina. Relations Anteriorly: internal iliac vessels and their branches, and rectum. Posteriorly: piriformis muscle.
Pelvic Nerves Branches of Sacral Plexus A. Branches to lower limb that leave pelvis through greater sciatic foramen: Sciatic nerve, Superior gluteal nerve, Inferior gluteal nerve, Nerve to quadratus femoris muscle, Nerve to obturator internus muscle, & Posterior cutaneous nerve of thigh. B. Branches to the pelvis: Pudendal nerve (S2, 3, and 4), which leaves pelvis through greater sciatic foramen & enters perineum through lesser sciatic foramen. Nerves to piriformis muscle Pelvic splanchnic nerves: forms sacral part of parasympathetic system & arise from 2nd, 3rd & 4th sacral nerves. They are distributed to the pelvic viscera. C. Perforating cutaneous nerve: supplies skin of lower medial part of buttock
Pelvic Nerves - Lumbar Plexus
Obturator Nerve: It is a branch of lumbar plexus (L2, 3, and 4), emerges from medial border of psoas muscle in the abdomen, and accompanies lumbosacral trunk down into pelvis. It crosses the front of sacroiliac joint and runs forward on lateral pelvic wall in angle between internal and external iliac vessels. On reaching obturator canal (upper part of obturator foramen, which is devoid of obturator membrane), it splits into anterior and posterior divisions that pass through the canal to enter adductor region of thigh. It supply adductor muscles and sensory branches supply parietal peritoneum on lateral pelvic wall.
Pelvic Nerves - Autonomic Nerves
A. Pelvic Part of Sympathetic Trunk: Pelvic part of sympathetic trunk is continuous above, behind common iliac vessels, with abdominal part. It runs down behind rectum on front of sacrum, medial to anterior sacral foramina. Sympathetic trunk has 4 or 5 segmentally arranged ganglia. Below, the two trunks converge and finally unite in front of coccyx. Branches Gray rami communicantes to sacral and coccygeal nerves Fibers that join the hypogastric plexuses B. Pelvic Splanchnic Nerves form parasympathetic part of autonomic nervous system in pelvis. They arise from 2nd, 3rd & 4th sacral nerves & synapse in ganglia in inferior hypogastric plexus or in walls of viscera. Some of its fibers ascend through hypogastric plexuses & via aortic plexus to inferior mesenteric plexus.
Pelvic Nerves - Autonomic Nerves
Superior Hypogastric Plexus It is situated in front of promontory of sacrum & formed as continuation of aortic plexus and from branches of 3rd & 4th lumbar sympathetic ganglia. It contains sympathetic and sacral parasympathetic nerve fibers and visceral afferent nerve fibers. Superior hypogastric plexus divides inferiorly to form right and left hypogastric nerves. Inferior Hypogastric Plexuses Inferior hypogastric plexuses lie on each side of rectum, base of bladder, & vagina. Each plexus is formed from a hypogastric nerve (from superior hypogastric plexus) & from pelvic splanchnic nerve. It contains postganglionic sympathetic fibers, preganglionic & postganglionic parasympathetic fibers, and visceral afferent fibers.
Arteries of the Pelvis Common Iliac Artery.
Each common iliac artery ends at pelvic inlet in front of sacroiliac joint by dividing into external and internal iliac arteries External Iliac Artery External iliac artery runs along medial border of psoas muscle, following pelvic brim, & gives off inferior epigastric & deep circumflex iliac branches. It leaves false pelvis by passing under inguinal ligament to become femoral artery. Arteries of the True Pelvis Internal iliac artery Superior rectal artery (IMA) Ovarian artery (Aorta) Median sacral artery (Aorta)
Arteries of the Pelvis Internal Iliac Artery: passes down into pelvis & divides into anterior and post. divisions. It supplies pelvic viscera, perineum, walls & buttocks. Branches of Anterior Division 1. Umbilical artery: From its proximal patent part arises superior vesical artery (supplies upper portion of bladder) 2. Obturator artery: accompany obturator nerve to obturator canal. 3. Inferior vesical artery: supplies base of bladder, prostate & seminal vesicles in male; also gives artery to vas. 4. Middle rectal artery: arises with inferior vesical artery. It supplies muscle of lower rectum & anastomoses with superior & inferior rectal arteries. 5. Internal pudendal artery: leaves pelvis through greater sciatic foramen & enters gluteal region below piriformis muscle. It then enters perineum by passing through lesser sciatic foramen. It supplies skin & muscles of perineum & anal canal.
Arteries of the Pelvis Internal Iliac Artery: passes down into pelvis & divides into anterior and post. divisions. It supplies pelvic viscera, perineum, walls & buttocks. Branches of Anterior Division 6. Inferior gluteal artery: leaves pelvis through greater sciatic foramen below piriformis muscle. It passes between 1st & 2nd or 2nd & 3rd sacral nerves. 7. Uterine artery: runs medially on Pelvic floor & crosses ureter superiorly. It passes above lateral fornix of vagina to reach uterus. Here, it ascends between layers of e broad ligament along the lateral margin of uterus. It ends by following uterine tube laterally, where it anastomoses with ovarian artery. Uterine artery gives off a vaginal branch. 8. Vaginal artery: takes place of inferior vesical artery present in male. It supplies vagina and base of bladder.
Arteries of the Pelvis Internal Iliac Artery: passes down into pelvis & divides into anterior and post. divisions. It supplies pelvic viscera, perineum, walls & buttocks. Branches of Posterior Division: A. Iliolumbar artery: ascends across pelvic inlet posterior to external iliac vessels, psoas, and iliacus muscles. B. Lateral sacral arteries: descend in front of sacral plexus, giving off branches to neighboring structures. C. Superior gluteal artery: leaves pelvis through greater sciatic foramen above piriformis muscle. Median Sacral Artery It is a small artery that arises at bifurcation of aorta. It descends over anterior surface of sacrum and coccyx.
Arteries of the Pelvis Superior Rectal Artery It is a direct continuation of inferior mesenteric artery. It supplies mucous membrane of rectum and upper half of anal canal. Ovarian Artery It arises from abdominal part of aorta at level of 1st lumbar vertebra & passes downward & laterally behind peritoneum. It crosses external iliac artery at pelvic inlet & enters suspensory ligament of ovary. It then passes into broad ligament & enters ovary by way of mesovarium.
Veins of the Pelvis External Iliac Vein It begins behind inguinal ligament as a continuation of femoral vein. It runs along medial side of corresponding artery & joins internal iliac vein to form common iliac vein. It receives inferior epigastric & deep circumflex iliac veins. Internal Iliac Vein Internal iliac vein begins by joining together of tributaries that correspond to branches of internal iliac artery. It passes upward in front of sacroiliac joint and joins external iliac vein to form common iliac vein. Median Sacral Veins Median sacral veins accompany corresponding artery and end by joining left common iliac vein
Lymphatics of the Pelvis
Lymph nodes & vessels are arranged in a chain along main blood vessels. Nodes are named according to blood vessels with which they are associated. Thus, there are external iliac nodes, internal iliac nodes, and common iliac nodes.
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