Flashcards in ANS Learning Objectives Deck (35):
located at L!, tapered termination of spinal cord proper
continuation of pia mater inferior to canus medullaris, descends to coccyx for inferior stabilization of spinal cord.
collection of nerve roots from end of spinal cord within lumbar cistern. traveling to vertebral foramina, inferior to conus medullaris
At which vertebral level does spinal cord terminate?
L1 vertebral level in adult. L3 in infant
clincal: do a spinal lumbar puncture below L1
continues as the cauda equina
How are 8 cervical nerves related to 7 cervical vertebra?
Named by the inferior vertebra. Starting above C1 (named C1 nerve) to above T1 (C8 nerve)
** below that, thoracic nerves are named by the superior vertebra
discrete group of neuronal cell bodies in CNS
discrete group of neuronal cell bodies in PNS
List the three meninges that wrap the spinal cord, in order to superficial to deep.
What fills the subarachnoid space?
this is deep to the arachnoid membrane, between the arachnoid and pia mater. filled with CSF (cerebrospinal fluid)
Where is the epi(extra)dural space & what is found within it?
Superficial to the dura mater, but contained in the vertebral column. Internal plexus of veins that drain spinal cord.
What is the denticulate ligament?
extensions of the pia mater along the lateral side of the spinal cord that provide lateral stabilization.
How do the ventral/dorsal roots differ from ventral/dorsal rami?
Ventral roots carry motor information to CNS from effector areas. Dorsal roots sent CNS information (sensory) to effector areas. Ventral rami innervate the anterior 2/3 of the body. Dorsal rami innervate posterior 1/3 of the body.
Dorsal ramus remains segmented.
Ventral can remain segmented as dermatome, or unite with others to form plexus.
What vertebral levels exhibit "typical" (segmental) spinal nerves?
What is a dermatome?
a strip of skin supplied by sensory branches of dorsal and ventral rami from one spinal cord level.
What is cutaneous innervation?
area of skin that is innervated by a peripheral nerve which may or may not have one spinal cord level within it
Key Dermatome Levels
Top of skull: C2
Upper Neck: C3
Lower Neck: C4
Umbilicus: T10 (appendix pain)
For complete cutaneous sensory loss, how many spinal nerves would have to be lesioned? Why?
dermatomes overlap upper and lower by approximately 50%, so 3 levels.
What types of fibers (modality) are found in the dorsal/ventral roots?
What is the first point where nerves become mixed?
True spinal nerve
What do somatic motor neurons innervate? Where are their cell bodies of origin? How many nerves make this up?
One neuron system. A single neuron links a peripheral target. Output from CNS to skeletal muscle of trunk or limbs. Cell body is in nucleus. (ventral root)
What do somatic sensory neurons innervate? Where are their bodies of origin located? How many neurons?
skin or skeletal muscle. single neuron links a peripheral target. cell body is in ganglion (cell bodies OUTSIDE CNS). one neuron
What do visceral sensory neurons innervate? Where are their cell bodies of origin located? How many neurons link them to the target?
Relay information to and from the body viscera. Cell bodies are in the dorsal root ganglion (sometimes get mixed up with the somatic sensory neurons). there's only one neuron between them and their target.
What do visceral motor (ANS) innervate?
Smooth muscle, cardiac muscle, glands.
Is the autonomic nervous system a sensory or motor system or both? How many nerves link the CNS to the target?
Motor system with two divisions. Each division has two neurons to link the CNS TO THE TARGET.
What is the difference between somatic and visceral nervous system?
Somatic--> information between CNS and body wall/extremities, one neuron system.
Visceral-->conveys impulses between CNS and blood vessels, glands, or internal organs. Two divisions. ANS (two neuron). Sensory (1 neuron)
What are the divisions of the ANS? What are their functions?
Parasympathetic--rest or digest
Sympathetic--fight or flight
Where are the neuron cell bodies located for each division of the ANS located in CNS? Based on this, what are their anatomical-based name for each?
Preganglionic--body in CNS (synapse with postganglionic)
Post ganglionic--body in autonomic ganglion
Which of 2 of the 3 types of autonomic ganglia are associated with sympathetic synapse in ANS? Which is strictly involved in parasympathetic? Where are they found?
Sympathetic--Paravertebral/sympathetic trunk (directly anterior to vertebral column. Prevertebral (anterior to vertebral, closer to abdomen)
. All of the cell bodies are located in the ICM (intermediolateral cell column) of spinal cord) Parasympathetic--Intramural, wall of target organ, except for the head.
What is the function of the sympathetic trunk?
Runs base of skull to base of coccyx... distribute sympathetic innervation throughout body since these nerves only run T1-L2.
How do white and gray rami communicans differ? What is the function? Which is more numerous? Why?
White are mylinated, and they are the on ramp to the sympathetic trunk. they contain preganglionic and visceral afferent (sensory) nerves. they are only located L1-T2 because that's the only supply of nerves (for the on rap) to the sympathetic trunk.
Grey are not mylinated. they are the off ramp from sympathetic nervous system and are located through all levels that exhibit sympathetic ganglion. they are needed to transport the signal to effector
What is a splanchnic nerve? What fiber can splanchnic nerves contain?
it is a nerve that goes directly to an organ. they can contain post synaptic and presynaptic motor nerves, as well as visceral sensory nerves
List the autonomic ganglia of the head associated with the parasympathetic division of the ANS.With which cranial nerve are they associated?
Ciliary (CN III)
Otic (CN IX)
Pterygopalatine and Submandibular (CN VII)
Vagus (CN X), not confined with head (2/3 of the body)
Cranial nerves may contain motor, sensory, and parasympathetic fibers, but never sympathetic.
Which cranial nerve is responsible for the parasympathetic innervation of the thorax and abdomen?
Vagus, uses intramural ganglia exclusively.
Where are the cell bodies for the parasympathetic division of the ANS localized?
Nuclei of the brain stem (Cranial nn. )and spinal cord segments S2-S4 (pelvic splanchnic). Craniosacral distribution.