Definitions

Body wall

Thoracic and abdominopelvic wall, parietal pericardium, and diaphragm and their coverings of parietal pleura or peritoneum (innervated by spinal rami)

Body cavity

Organs and their coverings of visceral pleura, pericardium, or peritoneum (innervated by visceral sensory and autonomic nerves to glands and smooth and cardiac muscle)

Visceral vs. somatic nerve plexuses

The former innervates viscera in the body cavity, while the latter one supplies only the body wall

Referred pain    (Tips) 

The transmittance of pain from structures within the body cavity to the same dorsal root ganglia and spinal cord segments that are receiving GSA (PAIN) information from the body wall.  The patient "perceives" that the pain is in the body wall when it arises in the organ

Body wall (somatic) innervation

Ventral rami

Interocostal nerves (T₁-T₁₂)

Somatic plexuses

Cervical-phrenic nerve

Lumbosacral-ilioinguinal, iliohypogastric, genitofemoral, pudendal (perineal) nerves, and nerves of the lower limbs

Dorsal rami - T_1-12 and cluneal nerves (L₁-L₃ & S₁-S₃).  Note: these nerves are important for referred pain from thoracic organs and from abdominopelvic retroperitoneal organs and the intraperitoneal uterine tube

Same four functional components as in Unit 1

GSA (dorsal root ganglia)

GSE (ventral horn)

GVA (dorsal root ganglia)

GVE sympathetics postganglionic (chain ganglia)

Autonomic nervous system (ANS)

Efferent or motor (GVE) ONLY

Two parts

Sympathetic - thoracolumbar (T₁ to L₂ or L₃)

Parasympathetic - craniosacral (Cns. III, VII, IX and X; S₂ to S₄)

Two multipolar neuron hookup, i.e., preganglionic and postganglionic

The autonomic nerve fibers innervate glands, smooth and cardiac muscles composing the viscera and vasculature

Autonomic fibers innervate viscera and vasculature by forming nerve plexuses on them (all visceral plexuses are named for the organ they supply; e.g., cardiac nerves form the cardiac plexus which innervates the heart)

These nerves (e.g., cardiac nerves of the cardiac plexus) carrying autonomic (GVE) fibers also serve as pathways for afferent (GVA) nerve fibers transmitting sensory information from viscera back into the CNS

GVA (PAIN) fibers (with the exception of pelvic splanchnic nerves) co-localize with sympathetics

GVA (enteroceptive) fibers co-localize with the parasympathetics

Aortic bodies - chemoreceptors for Po₂ and pH

Aortic sinus - baroreceptors for blood pressure

Airways - irritant receptors for coughing

GI and urinary bladder - stretch receptors for fullness

Thoracic visceral plexus (on blood vessels and named for the organ they innervate)

GVE sympathetic postganglionic (sympathetic chain ganglia)

GVA (pain) co-localizing with sympathetics above (dorsal root ganglia)

GVE parasympathetic preganglionic (vagus)

GVA (enteroceptive) co-localizing with parasympathetics above (vagus)

Abdominopelvic visceral plexuses have four functional components and are similar to those seen in the thorax except for three basic differences

GVE sympathetic postganglionics are prevertebral (preaortic) in location and preganglionic fibers are distributed to them by splanchnic nerves

GVE parasympathetic preganglionics are distributed by the vagus nerves and pelvic (splanchnic) nerves-the homologue of the vagus nerves to the pelvic cavity and genitals

GVA fibers which co-localize with pelvic splanchnic nerves carry BOTH enteroceptive and pain information