ANS Learning Objectives

Question 1

Conus medullaris

Answer 1

located at L!, tapered termination of spinal cord proper

Question 2

Filum terminale

Answer 2

continuation of pia mater inferior to canus medullaris, descends to coccyx for inferior stabilization of spinal cord.

Question 3

Cauda Equina

Answer 3

collection of nerve roots from end of spinal cord within lumbar cistern. traveling to vertebral foramina, inferior to conus medullaris

Question 4

At which vertebral level does spinal cord terminate?

Answer 4

L1 vertebral level in adult. L3 in infant
clincal: do a spinal lumbar puncture below L1
continues as the cauda equina

Question 5

How are 8 cervical nerves related to 7 cervical vertebra?

Answer 5

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

Question 6

Nucleus

Answer 6

discrete group of neuronal cell bodies in CNS

Question 7

Ganglion

Answer 7

discrete group of neuronal cell bodies in PNS

Question 8

List the three meninges that wrap the spinal cord, in order to superficial to deep.

Answer 8

Dura mater
Arachnoid
Pia

Question 9

What fills the subarachnoid space?

Answer 9

this is deep to the arachnoid membrane, between the arachnoid and pia mater. filled with CSF (cerebrospinal fluid)

Question 10

Where is the epi(extra)dural space & what is found within it?

Answer 10

Superficial to the dura mater, but contained in the vertebral column. Internal plexus of veins that drain spinal cord.

Question 11

What is the denticulate ligament?

Answer 11

extensions of the pia mater along the lateral side of the spinal cord that provide lateral stabilization.

Question 12

How do the ventral/dorsal roots differ from ventral/dorsal rami?

Answer 12

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.

Question 13

What vertebral levels exhibit “typical” (segmental) spinal nerves?

Answer 13

T2-T12

Question 14

What is a dermatome?

Answer 14

a strip of skin supplied by sensory branches of dorsal and ventral rami from one spinal cord level.

Question 15

What is cutaneous innervation?

Answer 15

area of skin that is innervated by a peripheral nerve which may or may not have one spinal cord level within it

Question 16

Key Dermatome Levels

Answer 16

Top of skull: C2
Upper Neck: C3
Lower Neck: C4
Nipples: T4
Xiphoid: T7
Umbilicus: T10 (appendix pain)

Question 17

For complete cutaneous sensory loss, how many spinal nerves would have to be lesioned? Why?

Answer 17

dermatomes overlap upper and lower by approximately 50%, so 3 levels.

Question 18

What types of fibers (modality) are found in the dorsal/ventral roots?

Answer 18

Dorsal–sensory

Ventral–motor,

Question 19

What is the first point where nerves become mixed?

Answer 19

True spinal nerve

Question 20

What do somatic motor neurons innervate? Where are their cell bodies of origin? How many nerves make this up?

Answer 20

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)

Question 21

What do somatic sensory neurons innervate? Where are their bodies of origin located? How many neurons?

Answer 21

skin or skeletal muscle. single neuron links a peripheral target. cell body is in ganglion (cell bodies OUTSIDE CNS). one neuron

Question 22

What do visceral sensory neurons innervate? Where are their cell bodies of origin located? How many neurons link them to the target?

Answer 22

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.

Question 23

What do visceral motor (ANS) innervate?

Answer 23

Smooth muscle, cardiac muscle, glands.

Question 24

Is the autonomic nervous system a sensory or motor system or both? How many nerves link the CNS to the target?

Answer 24

Motor system with two divisions. Each division has two neurons to link the CNS TO THE TARGET.

Question 25

What is the difference between somatic and visceral nervous system?

Answer 25

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)

Question 26

What are the divisions of the ANS? What are their functions?

Answer 26

Parasympathetic–rest or digest

Sympathetic–fight or flight

Question 27

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?

Answer 27

Preganglionic–body in CNS (synapse with postganglionic)

Post ganglionic–body in autonomic ganglion

Question 28

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?

Answer 28

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.

Question 29

What is the function of the sympathetic trunk?

Answer 29

Runs base of skull to base of coccyx… distribute sympathetic innervation throughout body since these nerves only run T1-L2.

Question 30

How do white and gray rami communicans differ? What is the function? Which is more numerous? Why?

Answer 30

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

Question 31

What is a splanchnic nerve? What fiber can splanchnic nerves contain?

Answer 31

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

Question 32

List the autonomic ganglia of the head associated with the parasympathetic division of the ANS.With which cranial nerve are they associated?

Answer 32

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.

Question 33

Which cranial nerve is responsible for the parasympathetic innervation of the thorax and abdomen?

Answer 33

Vagus, uses intramural ganglia exclusively.

Question 34

Where are the cell bodies for the parasympathetic division of the ANS localized?

Answer 34

Nuclei of the brain stem (Cranial nn. )and spinal cord segments S2-S4 (pelvic splanchnic). Craniosacral distribution.

Question 35

What are the enlargements of the spinal cord? Why do they exist? What is the specific function of each enlargement?

Answer 35

Cervical and Lumbar enlargements
Correspond to where the large nerves that supply different areas
Cervical– upper limbs
Lumbar–lower limbs