Anatomy & Physiology - Ch 13

In which plexus does the ulnar nerve arise?*

brachial plexus

What do somatic reflexes activate?

skeletal muscles

Which would the delay b/t stimulus and response be greater? A monosynaptic or a polysynaptic reflex.*

polysnaptic

Spinal nerves are both?*

sensory and motor

What are some characteristics of polysynaptic reflexes?*

- have reverberating circuits that prolong the reflexive motor response - involve reciprocal innervation - are intersegmental in distribution - involve pools of interneurons - NOT: arranged according to dermatomes

The SC consists of how many regions and how many segments?*

5 regions & 31 segments

How many of each, cervical spinal nerves, thoracic spinal nerves, lumbar spinal nerves, sacral spinal nerves and coccygeal spinal nerves?

8 - cervical nerves 12 - thoracic nerves 5 - lumbar nerves 5 - sacral spinal nerves 1 - coccygeal spinal nerves

Postganglionic fibers of the ANS that innervate internal organs do not rejoin the spinal nerve but form?

???

What does the gray matter of the spinal cord mostly contain?

???

What does the obturator nerve innervate?

???

What does the somatic motor neurons in the spinal cord control, which muscle groups?

???

What forms the gray rami communicantes?

???

What forms the white rami communicantes?

???

What innervates most of the muscles of the neck and shoulder?

???

What is an epidural block?

???

What is divergence?

???

What is meningitis & what causes it?

???

What is the coccygeal ligament?

???

If something brushes against your abdomen, the sensory information is carried on what ramus?

dorsal ramus

What is a lumbar puncture?

during this procedure, a needle is inserted into the subarachnoid space in the inferior lumbar region

Each peripheral nerve provides what kind of innervation to the peripheral structures?

either one or several

What are the outward projections from the central gray matter of the spinal cord?*

horns

What is a stretch reflex?

important in regulation skeletal muscle length

What is reverberation?

in reverberation, axon collaterals extend back toward the source of the impulse and further stimulate the earlier neurons

Where do enlargements of the spinal cord occur?

in the spinal segments that control the limbs

Reflexes that activate muscles on the same side of the body as the stimulus are called?

ipsilateral

What happens if a dorsal root of a spinal nerve is severed?

sensory input would be blocked

What do the posterior horns of the spinal cord contain mainly?*

sensory nuclei

Samples of CSF for diagnostic purposes are normally obtained by placing a tip of a needle in the?

subarachnoid space

What does the phrenic nerve innervate?

the cervical plexus

Where is the pia mater?

the innermost layer of the meninges, meaning it is attached directly to the brain and the spinal cord

What is the perinuerium?

the layer of connective tissue that surrounds a fascicle within a peripheral nerve

What is the endoneurium?

the layer of connective tissue that surrounds individual axons within a peripheral nerve is termed

What is the pia mater?

the layer of the meninges in direct contact with the spinal cord

Spinal nerves from the sacral region innervate what muscles?

the leg muscles

What is a reflex arc?

the neural "wiring" of a single reflex

What is the epineurium?

the outermost connective tissue covering of nerves

If a person has a crush injury to the C3-C5 spinal segments, you would expect what to possibly occur?

the person might not be able to breathe on their own

What is a tendon reflex?*

the reflex that prevents a muscle from exerting too much tension

What does the dorsal ramus innervate?

the skin and muscles of the back

What is the gray commissure?*

where axons crossing from one side of the spinal cord to the other within the gray matter are found

What does the dorsal root of the spinal nerve contain?*

axons of sensory neurons

Blood vessels that supply the spinal cord run along the surface of the?*

pia mater

What layer of the meninges is in direct contact with the spinal cord?

pia mater

After age ____ the vertebral column continues to elongate, but the spinal cord does not.*

4

What are some characteristics of neural reflexes?*

- are the simplest form of behavior - help preserve homeostasis - involve at least 2 neurons - are automatic motor responses - NOT cannot be modified by the brain

What are some characteristics of muscle spindles?*

- consist of specialized fibers called intrafusal fibers - are innervated by gamma motor neurons - are the receptor for the stretch reflex - are found within skeletal muscle - NOT are found in tendons

What are the four major plexuses of the ventral rami?

1) cervical 2) brachial 3) lumbar 4) sacral

What is paraplegia?

a condition in which a person loses all feeling and movement of the legs due to a spinal cord injury

What is shingles?

a condition in which a virus infects dorsal root ganglia, causing a painful rash whose distribution corresponds to that of the affected sensory nerves as seen in their dermatomes

What is the Babinski reflex?*

a positive Babinski reflex is normal for newborns & abnormal in adults; could be a sign of injury to descending spinal tracts; will cause the toes to flare when the sole is stroked

What is reciprocal inhibition?*

a process in which spinal interneurons inhibit antagonist motor neurons

What is a monosynaptic reflex?

a reflex in which a sensory neuron synapses directly on a motor neuron

What is a polysynaptic reflex?

a reflex in which at least one interneuron is placed between the sensory and motor neuron

The dorsal and ventral root of each spinal segment unite to form?

a spinal nerve

What does the epidural space contain?

areola tissue and blood vessels

In an adult, where is the conus medullaris found?

at about the L1 vertebra

What does the ventral root of a spinal nerve contain?*

axons of motor neurons

Where is the subdural space?*

between the dura mater and the arachnoid mater

What does the white bundle of the spinal cord contain?*

bundles of axons with common origins, destination, and functions

The white matter of the spinal cord has mainly what types of axons?*

myelinated & unmyelinated

What does the dorsal root ganglia mainly contain?*

cell bodies of sensory neurons

The spinal cord is part of the?*

central nervous system

What plexus supplies innervation to the diaphragm?

cervical plexus (phrenic nerve)

What are the ascending and descending tracts organized as?*

columns

What is a crossed extensor reflex?*

complements the flexor reflex by activation contralateral muscles

What is a plexus?

complex, interwoven network of nerve fibers; formed from the blended fibers of ventral rami of adjacent spinal nerves; control skeletal muscles of the neck and the limbs

What is quadriplegia?

condition in which a person loses all feeling and movement of the arms and legs due to a spinal cord injury

Reflexes that activate muscles on the opposite side of the body as the stimulus are called?

contralateral

What is included in a recognized neuronal circuit patterns?

diergence, convergence, serial processing, parallel processing, and reverberation

What are the two divisions to the sciatic nerve?

fibular nerve & tibial nerve

What nerves originate in the lumbar plexus?

genitofemoral nerve, lateral femoral cutaneous nerve, femoral nerve

Bill contracts a viral disease that destroys cells in the posterior gray horns in his spinal cord. As a result, which of the following would you expect?*

loss of sensation in his torso

What is the arachnoid mater?

middle meningeal layer between the dura mater (outer) and the pia mater (inner)

What is a flexor reflex?*

moves a limb away from a painful stimulus

If a viral disease destroys the cells of the anterior gray horn what might happen?

muscle weakness or paralysis

The gray horns of the spinal cord contain mainly?*

nerve cell bodies

The brachial plexus gives rise to all of the following nerves, except the?*

phrenic

What are innate reflexes?

reflexes based on synapses formed during development

How are reflexes classified?*

reflexes can be classified by: - their development - where information processing occurs - the motor response - the complexity of the neural circuit

What is an intersegmental reflex arc?

reflexes that involve multiple segments of the spinal cord and can produce complex and coordinated responses

Compared to the vertebral column, the spinal cord is?

shorter

What do the anterior horns of the spinal cord contain mainly?*

somatic motor nuclei

What are the spinal meninges?

specialized membranes that isolate the spinal cord from the surroundings ; functions include: protecting the spinal cord & carrying blood supply

What is the epidural space?

the space that separates the dura mater from the walls of the vertebral canal

What is the subarachnoid space?*

the space where blood vessels travel within in so that they can deliver oxygen and nutrients to the spinal cord

What is a dermatome?

the specific strip of skin that is innervated by a specific spinal nerve

Where does the CSF flow within?

the subarchnoid space

What is the filum terminale?*

the thin thread of fibrous tissue at the end of the conus medullaris that attaches to the coccygeal ligament

What is the dura mater?*

the tough, fibrous, outermost covering of the spinal cord

What does the ventral ramus innervate?

the ventrolateral body surface, the structures in the body wall, and the limbs

Nerve tracts or fascicule make up what column?*

the white column