CHAPTER 13 Flashcards
“Somatosensory” does not refer to sensory signals from_________.
the viscera
A ganglion is a swelling along a nerve containing the cell bodies of peripheral neurons.
True or False
True
A ganglion is a_________.
cluster of cell bodies in the PNS
A mixed nerve consists of both_________ and_________.
afferent; efferent fibers
A reflex in which the sensory input and motor output are on opposite sides of the spinal cord is called_________.
contralateral
A simple spinal reflex typically involves how many neurons?
three
A stretch reflex is often accompanied by reciprocal inhibition.
True or False
True
A_________ is a cordlike organ composed of numerous________
nerve; axons
Cell bodies of the anterior root are located in the_________.
gray matter
Cerebrospinal fluid fills the space between the_________.
arachnoid mater and pia mater
Epidural anesthesia is introduced to the epidural space between the_________ to block pain signals during pregnancy.
dural sheath and vertebral bones
Eyes and ears are innervated by_________ fibers.
special
Interneurons are located in the_________.
spinal cord
Many upper motor neurons synapse with lower motor neurons in the_________.
anterior horn
Motor commands are carried by_________ from the brain along the spinal cord.
descending tracts
Nerve fibers are insulated from one another by_________.
endoneurium
Nerve fibers in a given white matter tract are similar in origin, destination, and function.
True or False
TRue
Reflex arcs that only use two neurons are called_________ reflex arcs.
monosynaptic
Second-order neurons synapse with third-order neurons in the_________.
thalamus
Sensory stimuli enter the spinal cord via_________.
afferent axon
Somatic reflexes are responses of skeletal, smooth, and cardiac muscles.
True
False
False
The bundle of nerve roots that occupy the vertebral canal from L2 to S5 is called the_________.
cauda equina
The cervical plexus is the origin of the_________ nerve(s).
phrenic
The connective tissue that surrounds a nerve fascicle is called the _________.
perineurium
The fibers that carry the action potentials that cause skeletal muscle to contract are_________.
alpha motor neurons
The middle layer of the meninges is called the_________.
arachnoid mater
The upper motor neurons that control skeletal muscles begin with a body in the_________.
precentral gyrus of the cerebrum
There are_________ pairs of spinal nerves.
31
Voluntary motor impulses leave the spinal cord via the_________ of gray matter.
anterior horn
Which of the following branches of a spinal nerve has the cell bodies of only sensory neurons?
Posterior (dorsal) root
Which of the following fractures would be the least likely to cause a spinal cord injury?
A fracture of vertebra L4
Which of the following is comprised of anterior rami from C5-T1?
Brachial plexus
Which of the following is contained within gray matter?
Cell bodies, dendrites, and proximal parts of axons of neurons
Which of the following is not a distal branch of the spinal nerve?
Posterior root
Which of the following is not a function associated with the spinal cord?
Protect neurons in both the ascending and descending tracts
Which of the following is not a property of reflexes?
Reflexes do not require a stimulus.
Which of the following is not considered a region of the spinal cord?
Pelvic
Which of the following nerves originates in the lumbosacral plexus?
Sciatic
Which of the following sensory functions involves neurons in the posterior root ganglion?
Touch
Which of the following structures is the richest in lipid content?
White matter
Which one of the following best describes the order of a somatic reflex?
Somatic receptor → afferent nerve fiber → interneuron → efferent nerve fiber → skeletal muscle
