Spine and Extremities Autonomic Nuggets Study Guide - Page 1

Vocabulary flashcards covering key terms and definitions from the autonomic nervous system notes.

Sympathetic trunks

Bilateral nerve chains running from C1 to the coccyx that carry pre- and post-synaptic sympathetic fibers via white and gray rami.

Intermediolateral cell column

Spinal cord region at T1-L2 where pre-synaptic sympathetic neuron cell bodies reside.

White rami communicantes

Myelinated preganglionic sympathetic fibers entering the sympathetic trunk from spinal nerves.

Gray rami communicantes

Unmyelinated postganglionic sympathetic fibers exiting the sympathetic trunk to join spinal nerves.

Pre-synaptic sympathetic fibers

Sympathetic fibers originating in the IML that travel via white rami to synapse or pass through to prevertebral ganglia.

Post-synaptic sympathetic fibers

Sympathetic fibers exiting ganglia via gray rami (or other routes) to reach target organs.

Sympathetic ganglia

Paravertebral ganglia along the sympathetic trunk where pre- and post-synaptic fibers may synapse.

Greater splanchnic nerve

Preganglionic sympathetic fibers (T5-T9) traveling to the celiac ganglion to synapse.

Lesser splanchnic nerve

Preganglionic sympathetic fibers (T10-T11) traveling to abdominal ganglia (e.g., SMA/IMA region) to synapse.

Least splanchnic nerve

Preganglionic sympathetic fibers (T12) traveling to the inferior mesenteric region to synapse.

Pre-vertebral (pre-aortic) ganglia

Ganglia anterior to the aorta (celiac, superior mesenteric, inferior mesenteric) where preganglionic sympathetic fibers synapse.

Celial ganglion

Prevertebral ganglion at the celiac trunk receiving greater splanchnic input.

Superior mesenteric ganglion

Prevertebral ganglion receiving input from lesser splanchnic nerves for midgut organs.

Inferior mesenteric ganglion

Prevertebral ganglion receiving input from least splanchnic nerves for hindgut organs.

Post-synaptic sympathetic fiber distribution

Postganglionic fibers distribute to abdominal organs by following the bases of arteries.

Vagus nerve

Cranial nerve X; provides preganglionic parasympathetic innervation to thorax and abdomen up to the left colic flexure.

Pelvic splanchnic nerves

Parasympathetic preganglionic nerves from S2-S4 to the pelvis and left colic flexure.

Pre-synaptic parasympathetic fibers

Parasympathetic fibers that originate in the brainstem or sacral spinal cord and synapse in intrinsic ganglia.

Post-synaptic parasympathetic cell bodies

Parasympathetic neuron cell bodies located in organ walls or intrinsic ganglia.

Intrinsic ganglia

Post-synaptic parasympathetic neuron clusters within organ walls.

Parasympathetic distribution

Parasympathetic innervation mainly targets smooth muscle, cardiac muscle, and glands of internal organs.

Visceral structures of the skin

Skin structures (blood vessels, arrector pili, glands) receiving only post-synaptic sympathetic innervation.

Arrector pili muscles

Smooth muscles in hair follicles innervated by post-synaptic sympathetic fibers.

Sweat glands

Glands in skin innervated by post-synaptic sympathetic fibers.

Autonomic plexuses

Extensive networks of autonomic fibers around major vessels and organs.

Sympathetic contribution to plexuses

Predominantly post-synaptic sympathetic fibers in plexuses.

Parasympathetic contribution to plexuses

Predominantly pre-synaptic (preganglionic) parasympathetic fibers in plexuses.

Diffuseness of autonomic plexuses

Plexuses are diffuse networks, making it hard to trace a single component to an organ.

Abdominal autonomic plexuses

Plexuses in the abdomen that wrap around major vessels to distribute to organs.

Parasympathetic pass-through of pre-vertebral ganglia

Parasympathetic preganglionic fibers can pass through prevertebral ganglia without synapsing.

Parasympathetics and paravertebral ganglia

Parasympathetics do not pass through paravertebral (sympathetic trunk) ganglia.

Paravertebral ganglia

Ganglia along the sympathetic trunk housing sympathetic neuron cell bodies.

Gray ramus distribution concept

Gray rami are present on all 31 spinal nerves; white rami occur only at T1-L2.

Dorsal and ventral rami

Branches of spinal nerves; carry mixed fibers and include gray rami with post-sympathetic fibers.

T1-L2: pre-synaptic cell bodies

Location of pre-synaptic sympathetic neuron cell bodies in the intermediate zone (IML).

Gray rami on all spinal nerves

All 31 spinal nerves contain gray rami carrying post-synaptic sympathetic fibers.

Pre-synaptic cell bodies location

In the intermediolateral column from T1 to L2.

Post-synaptic cell bodies location

In sympathetic chain ganglia or in target organ walls (intrinsic ganglia for parasympathetics).

Left colic flexure boundary

Vagus provides parasympathetic innervation up to the left colic flexure; beyond that, pelvic splanchnics provide innervation.

Vagus innervation extent

Vagus (CN X) supplies preganglionic parasympathetic innervation to thorax and abdomen up to left colic flexure.

Pelvic innervation (S2-S4)

Pelvic splanchnic nerves carry parasympathetic fibers from S2-S4 to pelvic organs.

Diaphragm piercing by splanchnic nerves

Greater, lesser, and least splanchnic nerves pierce the diaphragm en route to prevertebral ganglia.

Post-synaptic sympathetic fibers follow arteries

Postganglionic sympathetic fibers hitch a ride on arterial bases to reach abdominal organs.

Prevertebral ganglia location relative to aorta

Located anterior to the aorta (celiac, superior/inferior mesenteric).

Parasympathetics through pre-vertebral ganglia

Parasympathetic fibers can pass through prevertebral ganglia without synapsing.

Paravertebral vs prevertebral distinction

Paravertebral ganglia belong to the sympathetic trunk; prevertebral ganglia lie anterior to the aorta.

Sympathetic innervation of limbs

Limbs receive post-synaptic sympathetic fibers; there are no direct preganglionic fibers to limbs.

Autonomic plexus composition

Plexuses mix sympathetic post-synaptic and parasympathetic pre-synaptic fibers.

Abdominal plexus around major vessels

Plexuses wrap around major abdominal arteries to distribute fibers to organs.

Final concept: autonomic division overview

The autonomic system uses sympathetic and parasympathetic divisions with distinct pathways to organs.