Retroperitoneum II: Nerves and Nerve Plexus PDF

Retroperitoneum II: Nerves and Nerve Plexus Bi-Hung Peng, PhD Department of Neurobiology The University of Texas Medical Branch  Nerves of anterior abdominal wall Anterior ramus...

Retroperitoneum II: Nerves and Nerve Plexus Bi-Hung Peng, PhD Department of Neurobiology The University of Texas Medical Branch  Nerves of anterior abdominal wall Anterior ramus T5: xiphoid Thoraco-abdominal nerves continuation of intercostal nerves (T7-T11) Sub-costal nerve T10: umbilicus (T12) Iliohypogastric and Lumbar plexus Ilio-inguinal nerves (L1) L1: pubis  Lumbar plexus: somatic innervation 1) Useful reference; not really part of lumbar plexus  2,3) May divide before or after traversing muscle  6) Positioned on top of psoas muscle  4) Runs across iliacus muscle  5) Largest nerve; lateral to psoas muscle  7) Medial to psoas muscle   8) Easier to visualize when pelvis is dissected (1) (1) (2) (3) (2) (3) (6) (4) (6) (5) (7) (4) (5) (8) (7) Autonomic innervation (Sympathetic & Parasympathetic) ^ splanchnic  Functions of sympathetic and parasympathetic systems The overall function of the ANS is to preserve the homeostasis of the human body. Homeostasis results when various systems cooperate with each other to maintain an internal milieu in which the various parts of the body can function optimally. Homeostasis: Sympathetics Parasympathetics The sympathetic system can be The parasympathetic system can be thought of as that which triggers the thought of as “restorative”, in that it “fight or flight” response : heart rate generally counteracts the sympathetic increases, blood pressure rises, the system: pupillary constriction, pupil dilates to capture more light, etc. decreased heart rate, etc. It is important to note that components of these two systems are active most of the time (to varying degrees) and often cooperate with each other to carry out several tasks, such as urinary bladder control, defecation, etc.  Differences between sympathetics and parasympathetics 1. The axons of preganglionic parasympathetic fibers generally travel longer distances to reach ganglia that are closer to or within the target organ. In contrast, the axons of preganglionic sympathetic fibers end in ganglia that are generally closer to the spinal cord. 2. Both neurons of the parasympathetic system use acetylcholine as a neurotransmitter. In contrast, postganglionic sympathetic neurons use norepinephrine (preganglionic sympathetics use acetylcholine). Sympathetics: norepinephrine closer acetylcholine Parasympathetics: acetylcholine farther acetylcholine Another major difference is that sympathetic fibers reach all parts of the body, whereas parasympathetic fibers are not present in the limbs and are restricted to the head, body cavities and Parasympathetic Ganglion  Components of the sympathetic system The sympathetic system is composed of a complex arrangement of connections between neurons whose bodies reside in the spinal cord and neurons whose bodies reside in sympathetic ganglia. Ganglia have a very prominent role in the gross anatomy of the sympathetic Greeksystem. for “beside the There are two types: vertebrae” A) Paravertebral ganglia:  Cervical (3 pairs):  Superior (one pair) Latin for “in  Middle (one pair) the shape of  Inferior (one pair) Cervicothoracic a star”  Thoracic (12 pairs) ( stellate )ganglion  Lumbar (5 pairs)  Sacral (5 pairs) Greek for  Ganglion impar (one“in ganglion) front of the vertebrae” B) Prevertebral ganglia  Celiac (one pair)  Aorticorenal (one pair)  Superior mesenteric (usually one ganglion)  Inferior mesenteric (usually one ganglion)  Components of the parasympathetic system The parasympathetic system is more restricted than the sympathetic division: only the head, viscera and genitalia receive parasympathetic innervation (there is no parasympathetic innervation to the limbs). Most preganglionic parasympathetic fibers contact postganglionic neurons located in many small ganglia that are very near or within the organ being Latin for innervated. “wanderin They arise fromg” the dorsal motor nucleus of the vagus ( (CN X), located in the brainstem and from sacral segments S2 to S4 of the spinal cord. However, there are four pairs of discrete parasympathetic ganglia in the head:  Ciliary  Pterygopalatine  Otic  Submandibular These arise from brainstem nuclei that supply the oculomotor (CN III), facial (CN VII) and glossopharyngeal (IX) nerves.  Autonomic ganglia and plexus of the abdomen Sympathetic trunk: Thoracic, lumbar and [- Cervical] sacral splanchnic [- Thoracic] nerves - Lumbar - Sacral - Ganglion impar Prevertebral ganglia (symp): - Celiac - Aorticorenal - Superior mesenteric - Inferior mesenteric Vagus Plexus (symp + para): - Aortic - Superior mesenteric - Inferior mesenteric - Intermesenteric - Renal, testicular - Hypogastric - Superior - Inferior (pelvic) Pelvic splanchnic nerves (parasympathetic only!) [Note: sacral, lumbar (and brachial and cervical) plexus are somatic] Autonomics use arteries to reach target organs Autonomic innervation of the kidneys  General function of autonomics in abdomen Sympathetic Parasympathetic Intestinal arteries and arterioles: Intestinal arteries and arterioles:  Constricts  Dilate GI Tract: GI Tract:  Decreases peristalsis  Increases peristalsis  Decreases secretomotor functions  Increases secretomotor activites Kidneys:  Relaxes involuntary sphincters  Stimulates renin secretion: BP Kidneys:  Increases NaCl reabsorption: BP  Relaxes renal pelvis and calyces  Decreases glomerular filtration rate  Relaxes smooth muscle in ureters  Stimulates contraction of ureters Normal bladder function requires concerted action of both: 1. Voluntary command to void: relaxes external urethral sphincter (via pudendal nerve). 2. Sympathetic function (constriction of internal sphincter and relaxation of bladder wall) stops 3. Parasympathetic function (relaxation of internal sphincter and contraction of bladder wall) starts  Referral of visceral pain  Caused by distention, stretch, ischemic events of the mesentery, GI tract and visceral peritoneum covering.  Hollow tube organs: pain is initially perceived along the midline. - Foregut: epigastric region - Midgut (e.g., appendix): umbilical region - Hindgut: hypogastric region  it is only when the parietal peritoneum becomes irritated that the pain radiates towards location of lesion.  Solid organs: pain lies generally over organ.  4. Remove GI Tract Detach liver from diaphrag 3. Cut m 1. Tight & three Cut Blood vessels 2. Tight & Cut 1 7 2 3 6 8 4 L&R 5  1 Abdominal aorta and aortic plexus 2 Coeliac trunk 3 Common hepatic artery 4 Diaphragm 5 First lumbar spinal nerve 6 Gonadal vein, left 7 Inferior vena cava 8 Left inferior phrenic vessels 9 Left kidney 10 Left psoas major 11 Left renal artery 12 Left renal vein SRG SRG 13 Left suprarenal gland 14 Left suprarenal vein CT 15 Left ureter 16 Lymphatic vessels 17 Para-aortic lymph nodes 18 Pre-aortic lymph nodes 19 Right crus of diaphragm 20 Right gonadal vein 21 Right kidney 22 Right renal artery 23 Right renal vein 24 Right suprarenal gland IVA SMA 25 Right ureter R. Kidney LRV L. Kidney 26 Splenic artery 27 Subcostal nerve, left 28 Superior mesenteric artery GV Aorta GV  The left kidney (10) and suprarenal gland (13) are seen on the posterior abdominal wall. Much of the diaphragm has been removed but the oesophageal opening remains, with the end of the oesophagus (16) opening out into the cardiac part of the stomach and a (double) anterior vagal trunk (2) overlying the red marker. The posterior vagal trunk (18) is behind and to the right of the oesophagus. Part of the pleura has been cut away (17) to show the sympathetic trunk (22) on the side of the lower thoracic vertebrae. The left coeliac ganglion and the coeliac plexus (6) are at the root of the coeliac trunk (3). 1 Abdominal aorta SRG 2 Anterior vagal trunk (double, over marker) CT 3 Coeliac trunk CG Lt Kidney 4 Common hepatic artery 5 Inferior phrenic vessels 6 Left coeliac ganglion and coeliac plexus 7 Left crus of diaphragm 8 Left gastric artery SMA 9 Left gonadal vein 10 Left kidney RA 11 Left renal artery 12 Left renal vein 13 Left suprarenal gland RV 14 Left suprarenal vein 15 Left ureter 16 Lower end of oesophagus 17 Pleura (cut edge) G 18 Posterior vagal trunk V 19 Psoas major 20 Splenic artery Aorta 21 Superior mesenteric artery 22 Sympathetic trunk 23 Thoracic aorta  1 4 The section is through the centre of the kidney and has included the renal pelvis (9) and beginning of the ureter (10). The major vessels in the hilum (2) have been removed. 1 Cortex 2 Hilum 3 Major calyx 4 Medulla 2 5 Medullary pyramid 6 Minor calyx 9 7 Renal column 8 Renal papilla 3 9 Renal pelvis 10 Ureter 6 8 The two or three major calyces (3) unite to form the renal pelvis (9) which passes out 5 through the hilum (2) to become the ureter (10), often with a slight narrowing at the 10 junction. This is known as the pelvi-ureteric junction (PUJ) and is a site of renal stone obstruction. Iliohypogastric Nerve Ilio-inguinal nerve Lateral cutaneous nerve Genitofemoral nerve Obturator n. Femoral n. How to find the structures…. IVA Head Celiac Ganglion Diaphragm removed You may also see  Renal cysts Here (yellow star) is a much larger simple renal cyst of the upper pole. Other smaller cysts are also scattered around the kidney. The ureter exits south on the left. Such a large renal cyst would be seen on a radiographic imaging procedure, but could probably be distinguished from a neoplasm by its uniform fluid density and thin wall. Such simple cysts are unlikely to compromise renal function.  Abdominal Aortic Aneurysm  Rupture of an aneurysm (localized enlargement) of the abdominal aorta causes severe pain in the abdomen or back. If unrecognized, a ruptured aneurysm has a mortality rate of nearly 90% because of heavy blood loss.  Surgeons can repair an aneurysm by opening it, inserting a prosthetic graft (such as one made of Dacron), and sewing the wall of the aneurysmal aorta over the graft to protect it. Aneurysms may also be treated by endovascular catheterization procedures. Abdominal Aortic Aneurysm | University Hospitals (uhhospitals.org) Kidney Stones Questions?