Exam 2 Flashcards
Nerve plexuses
At spinal cord levels, except for T2-T12, the anterior rami converge and diverge from each other forming these web-like plexuses. These fibers of the anterior rami intermingle and are redistributed
Why do &2-T12 not have nerve plexuses
Bc these nerves are mainly distributed exclusively to the truck
What are mutlisegmental peripheral nerve
A nerve that arises from the plexus that also conveys fibers to all or parts of other adjacent dermatomes
What arises from the nerve plexus
-Each anterior ramus contributes fibers to multiple peripheral nerves via the nerve plexuses , each of these peripheral nerve contain fibers from multiple spinal nerves
Two types of fibers
- the fibers carried by spinal nerves - segmental innervation (get dermatomes)
-fibers carried via branches of a plexus (mutlisegmental nerves)
Visceral sensory fibers (reflex and pain)
- Both visceral reflex senstations and pain impulses travel on on viseceral afferent fibers and travel info in opposite directions as the mother fiber they accompany
-reflex accompanies parasympathetic while pain is sympathetic
Visceral autonomic motor fibers
-organized into sympathetic and parasympathetic division; bth involve a 2-neuron chain btwn CNS & effector cell
-Pre & post synaptic neurons
Pre & post synaptic neurons
- pre = preganglionic have cell bodies w/in CNS gray matter and stretch out to autonomic ganglia
-post = postganglionic wh/ have cell bodies w/in autonomic ganglia & stretch out to smooth, Cardiac or gland cells
Sympathetic nervous system - division
Splits into paraveterbral ganglia or prevertebral ganglia
Paravertebral ganglia
Linked to form right and left sympathetic trunks (all motor) on each side of the vertebral column.
Prevertebral ganglia
Are in the plexuses that surround the origins of the main branches of the abdominal aorta
Celiac ganglia
-is a prevertebral ganglia that surrounds the origin of the celiac trunk
Superior cervical ganglion
- A paravertbral ganglia AKA superior paravertebral ganglion wh/ lies at the base of the cranium (1 per each of the sympathetic trunk)
Ganglion impar
-is an unpaired paravertebral ganglia that forms inferiorly where the 2 sympathetic trunks unite at the level of the coccyx
Sympathetic nervous system route (pregranglionic)
Preganglionic neurons leave the spinal cord thru anterior roots (bc they are motor fibers) & enter the anterior rami. Almost immediately after all preganglionic fibers leave the anterior rami of these spinal nerves & pass to the sympathetic trunk thru white rami communicates. Within the the sympathetic truck their are 3 possible courses
What are the three possible courses
- Synapse immediately w/ a postganglionic nervous of the paravertebral ganglion at the same level
- Ascend or descend in the sympathetic trunk to synapse w/ a postganglionic neuron of a higher or lower paravertebral ganglion
- Pass thru the sympathetic trunk w/o synapsing, continuing thru an adominopelvic splanchnic nerve to reach & synapse w/in a prevertebral ganglion
Sympathetic NS (postganglionic neurons)
Postganglionic fibers destined to reach structures of the neck, body wall, and limbs pass from the paravertebral ganglia thru grey rami communicantes & into both the anterior rami and the posterior rami of all 31 pairs of the spinal nerves
Splanchnic nerves of the postganglionic neurons
Convey visceral motor fibers to the visceral of the body cavities, these nerves also carry visceral sensory fibers from the same visceral towards the CNS
Sympathetic fibers destined for the viscera of the thoracic cavity
Pass thru cardiopulmonary splanchnic nerves to enter the cardiac, pulmonary, & esophageal pleaxyses, these fibers are postganglionic
Sympathetic fibers that are innervation of viscera of the abdominopelvic cavity
They pass thru the abdominopelvic splanchnic nerves, including the greater splanchnic, lesser splanchnic, least splanchnic & lumbar splanchnic nerves. These fibers are preganglionic and postganglionic fibers exiting prevertebral ganglia
Parasympathetic NS division
Fibers of preganglionic parasympathetic motor neurons exit the CNS
-W/in CN III, VII, IX, & X these neurons have cell bodies w/in brainsteam
-thru anterior roots of sacral spinal nerves S2-4, these neurons have cell bodies in the sacral segments of the spinal cord at levels S2-S4
Pelvic splanchnic nerves
Carry preganglionic parasympathetic fibers, arise from rami of spinal nerves S2-4 & innverate pelvic visceral plus the descending colon
Structures that innervated via parasympathetic NS
Sacral (descending colon & down)& cranial (head, Ascending & transverse colon) parasympathetic outflow wh/ innervates: strucures of the head, thoracic, abdominopelvic cavities, & erectile tissues of clit & penis.
*W/ expection of the penis & clit. The parasympathetic NS Doesn’t reach the body wall or limbs
What are the pairs of synapse-containing parasympathetic ganglia that occur in the head?
-Ciliary ganglion
-Pterygopalatine ganglion
-Submandibular ganglion
-Otic ganglion