Postganglionic fibers in gray rami communicantes to corresponding ventral rami of spinal nerves distributed to the body wall
and lower limb
Give off three to four lumbar splanchnic nerves (presynaptic sympathetic fibers) medially to:
Intermesenteric plexus
Inferior mesenteric plexus
Superior hypogastric plexus
Postsynaptic fibers from these plexuses innerve nearby target organs.
Sympathetic (paravertebral) ganglia
Total of four abdominal sympathetic ganglia per trunk
Prevertebral sympathetic ganglia
Cell bodies of postsynaptic sympathetic neurons
Found in plexuses around roots of major branches of aorta
Aortic plexuses
Network of parasympathetic and sympathetic nerves
Parasympathetic mainly from posterior vagal trunk (see above)
Sympathetic fibers from thoracic and lumbar splanchnic nerves (Section 3: Thorax)
Contain prevertebral ganglia
Include:
Celiac plexus
Aorticorenal plexus
Renal plexus
Superior mesenteric plexus
Intermesenteric plexus
Inferior mesenteric plexus
Perivascular plexuses derived from the aortic plexuses
Visceral afferent fibers
Carry pain information
Travel with sympathetic fibers back to spinal cord
Referred pain
Information carried by visceral afferent fibers
Fibers travel back to T5-L2/3 spinal cord levels via thoracic and lumbar splanchnic nerves
Clinical phenomenon of referred pain is visceral pain perceived as somatic pain over the dermatomes innervated by cutaneous
nerves with fibers from those spinal cord levels:Organ Spinal Level Area of Referred Pain
Stomach T5-T9 Epigastric or left hypochondrium
Duodenum T5-T8 Epigastric or right hypochondrium
Jejunum T6-T10 Periumbilical
Ileum T7-T10 Periumbilical
Caecum T10-T11 Periumbilical or right lower quadrant
Appendix T10-T11 Periumbilical, then to right iliac fossa
Ascending colon T10-T12 Periumbilical or right lumbar
Sigmoid colon L1-L2 Left lower quadrant
Spleen T6-T8 Left hypochondrium
Liver & gallbladder T6-T9 Epigastric, later to right hypochondrium
Pancreas T7-T9 Inferior epigastrium
Kidney T10-L1 Small of back, flank
Ureter T11-L1 Loin to groinSomatic Nerves
Thoracoabdominal nerves
Ventral primary rami of T7-T11
Travel in the neurovascular plane between the internal oblique and transversus abdominis muscles
Innervate anterolateral abdominal wall, including parietal peritoneum
Subcostal nerves
Ventral primary rami of T12
Follow the inferior border of the 12th rib
Enter abdomen behind lateral arcuate ligaments
Cross quadratus lumborum muscles and pierces transversus abdominis muscles to enter neurovascular plane
Innervate anterolateral abdominal wall (including parietal peritoneum)
Lumbar plexus
Iliohypogastric nerve (L1)
Divides into lateral and anterior cutaneous branches
Pierces internal and external oblique muscles
Supplies buttocks and suprapubic region
Ilioinguinal nerve (L1)
Travels in inguinal canal
Joins spermatic cord after piercing internal abdominal oblique (Note: does not enter inguinal canal through deep inguinal
ring)
Provides cutaneous branches to skin of inguinal region
Genitofemoral nerve (L1,2)
Emerges from anterior surface of psoas major muscle
Genital branch enters deep inguinal ring to innervate the cremaster muscle
Femoral branch passes beneath inguinal ligament in vascular compartment to enter femoral triangle and provides
cutaneous branches to anteromedial thigh