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
