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27 Cards in this Set

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How many pairs of spinal nerves are there?

31

What is a dermatome?

A specific segment of skin supplied by a single pair of spinal nerves

Shingles

During initial infection, the chickenpox virus sometimes leaves the skin and invades the posterior root ganglion


Virus remains latent until adulthood


Rash of scaly, painful blisters (usually confined to one or a few adjacent dermatomes)

Nerve plexuses

A network of interweaving spinal nerves


Split into multiple "named" nerves that innervate various body structures


Principle plexuses (cervical, brachial, lumbar, and sacral)



Which spinal nerves make up the cervical plexus?

C1-C4

What does the cervical plexus innervated

Anterior neck and parts of the head and shoulders

What innervates the diaphragm?

Phrenic nerve

Which spinal nerves keep the diaphragm alive?

C3-C5

Which spinal nerves make up the brachial plexus?

C5-T1

What does the brachial plexus innervate?

Pectoral girdle and upper limbs

Which spinal nerves make up the lumbar plexus?

L1-L5

What does the lumbar plexus innervate?

Lower limb

Which spinal nerve innervated the anterior thigh muscles?

Femoral nerve

Which spinal nerves make up the sacral plexus?

L4-S4

What does the sacral plexus innervate?

Lower limb

Sciatic nerve

Innervates all of the lower limb except anterior/medial thigh


Divides into the tibial and common fibular (peroneal) nerve

What are the five steps of the reflex arc?

1. Receptor


2. Sensory (afferent) neuron


3. Interneuron


4. Motor (efferent) neuron


5. Effector

Monosynaptic reflexes

The simplest of all reflexes


No interneurons (faster)


Example: stretch reflex (knee-jerk)

Polysynaptic reflexes

More complex neural pathway


More than one synapse involving interneurons within the reflex arc


Example: withdrawal reflex

Differences between somatic nervous system and autonomic nervous system

Somatic:


1 somatic sensory neuron


1 somatic motor neuron




Autonomic:


1 visceral sensory neuron


2 autonomic motor neurons (preganglionic an postganglionic -- adds another level of control)

What is the autonomic nervous system divided into?

Sympathetic and parasympathetic divisions

What is the origin of the sympathetic division?

T1-L2

What are the functions of the sympathetic division?

"Fight or flight"


Activated in emergency situations and when excited or stressed

What is the origin of the parasympathetic nervous system?

Brainstem (CN III, VII, IX, and X)


Sacral spinal cord

What are the functions of the parasympathetic nervous system?

"Rest and digest"


Conserves energy and replenishes energy stores

________ are innervated by both sympathetic and parasympathetic divisions?

Most organs -- this is called dual innervation

Opposite effects on an organ can be achieved by...

increasing or decreasing activity in one division (sympathetic or parasympathetic)