Chapter 13 The Spinal Cord, Spinal Nerves, and Somatic Reflexes

The upper motor neurons that control skeletal muscles begin with a soma inthe precentral gyrus of the cerebrum.
The signals that control your handwriting travel down the spinal cord inthe corticospinal tract.
Many upper motor neurons synapse with lower motor neurons inthe anterior horns.
Which of the following sensory functions involves neurons in the posterior root ganglia?touch
The spinal cord is divided into all of the following regions exceptpelvic.
The following are all functions associated with the spinal cord exceptto protect neurons in both the ascending and descending tract.
Which of the following fractures would be the least likely to cause a spinal cord injurya fracture of vertebra L4
This figure shows a detail of the spinal cord, meninges and spinal nerves. What does “1” represent?posterior root of a spinal nerve
This figure shows a detail of the spinal cord, meninges and spinal nerves. What does “4” represent?arachnoid mater
Epidural anesthesia is introduced in the epidural space between ___ to block pain signals during pregnancy.dural sheath and vertebral bones
This figure shows a cross section of the spinal cord. What does “3” represent?anterior horn
Cerebrospinal fluid fills in the space betweenarachnoid mater and pia mater.
Which of the following structures is the richest in lipid content?white matter
Gray matter containsneurosomas, dendrites, and proximal parts of axons of neurons.
___ carry motor commands from the brain along the spinal cordDescending tracts
Second-order neurons synapse with third-order neurons in thethalamus.
___ keep(s) nerve fibers insulated from one another.Endoneurium
___ fibers innervate eyes and ears.Special
A ganglion is acluster of neurosomas in the PNS.
There are __ pairs of spinal nerves.31
This figure shows the anatomy of a nerve. What does “3” represent?perineurium
This figure shows the posterior aspect of spinal nerve roots and plexuses. What does “3” represent?brachial plexus
This figure shows the posterior aspect of spinal nerve roots and plexuses. What does “2” represent?the cervical enlargement
The ventral rami of the spinal nerves form nerve plexuses in all regions exceptthe thoracic region
The cervical plexus gives origin to the ___ nerve(sphrenic
Which of the following nerves originates in the coccygeal plexus?sciatic
This figure shows a dermatome map. A patient with no sensation in the left thumb would probably have a nerve damaged inC6
Which of these is an ascending tract of the spinal cord?the gracile fasciculus
A mixed nerve consists of bothafferent and efferent fibers
Which of the following branches of a spinal nerve have somas of solely sensory neurons?posterior (dorsal) root
The bundle of nerve roots that occupy the vertebral canal from L2 to S5 is called thecauda equina.
Somatosensory refers to these sensory signals except the sensory signals fromthe viscera.
Neurosomas of the posterior root are located in the ___, whereas neurosomas of the anterior root are located in the ___.posterior root ganglion; gray matter
A ___ is a cordlike organ composed of numerous ___.nerve; axons
Which one of the following best describes the order of a somatic reflex?somatic receptor afferent nerve fiber interneuron efferent nerve fiber skeletal muscle
Which of the following groups of muscles have the most muscle spindles?muscles of the hand
These are all properties of reflexes exceptreflexes are spontaneous actions of the nervous system.
A muscle spindle contains mostlymuscle fibers.
A nurse pricks your finger to type your blood. You flinch at the pain, pulling your hand back. This is called theflexor (withdrawal) reflex.
The quickest reflex arcs involve only two neurons, thus forming __ reflex arcs.monosynaptic
The flexor (withdrawal) reflex employs a ____, which maintains a sustained contraction.parallel after-discharge circuit
If a bee sting on the right thigh causes a quick involuntary reaction of the right arm, this would be an example ofan intersegmental reflex.
The sensitivity of the muscle spindle is maintained bygamma motor neurons.
The fibers that carry action potentials to cause skeletal muscle to contract arealpha motor neurons.
You go to the movies after a long day and you begin to nod off as soon as the movie starts. Your head starts to lower a little but this reflex causes your head to rise. This is called thestretch (myotatic) reflex.
In the patellar tendon reflex arc, the patellar ligament is stretched, which stretches the quadriceps femoris muscle of the thigh. This reflex will cause the quadriceps femoris tocontract and the antagonist muscles, the hamstrings, to relax.
A reflex where the sensory input and motor output are on opposite sides of the spinal cord is called a(n) _____ reflex arc.contralateral
The tendon reflexprevents overcontraction of a muscle.
This reflex shows the least synaptic delay.tendon reflex
Tendon organs areproprioceptors.
Light touch, tickle, itch, temperature, pain, and pressure are stimuli collected by which spinal tract?
A) gracile fasciculus
B) lateral corticospinal
C) ventral spinocerebellar
D) spinothalamic
D) spinothalamic
Balance and posture, regulation of awareness of pain are all signals of which motor spinal tract?
A) ventral spinocerebellar
B) dorsal spinocerebellar
C) ventral corticospinal
D) lateral reticulospinal
D) lateral reticulospinal
This segment of the spinal cord has 8 spinal nerves.
A) cervical
B) thoracic
C) lumbar
D) sacral
A) cervical
Muscle spindles are a type of proprioceptors that respond to stretching of the
A) tendon.
B) ligament.
C) muscle fibers.
D) nerve.
C) muscle fibers.
An example of a polysynaptic reflex arc is a _______ reflex.
A) reciprocal
B) flexor
C) stretch reflex
D) myotatic
B) flexor
This spinal cord tract carries information about position and movement of the lower extremities to the brain.
A) tectospinal
B) cuneate fasciculus
C) spinothalamic
D) gracile fasciculus
E) ventral corticospinal
D) gracile fasciculus
This area of the meninges has many smaller blood vessels and closely adheres to the outer surface of the central nervous system.
A) dura mater
B) subdural space
C) arachnoid membrane
D) subarachnoid space
E) pia mater
E) pia mater
Sensory neurons enter the spinal nerve cord at the
A) anterior root.
B) ventral root.
C) gray commissure.
D) lateral horns.
E) anterior median fissure.
B) ventral root.
Which branch of each spinal nerve gives rise to the nerves of the extremities?
A) posterior ramus
B) posterior root
C) anterior ramus
D) anterior root
C) anterior ramus
The brachial plexus innervates
A) arms and shoulders.
B) only the arm, but the whole arm.
C) the upper arm only.
D) the lower arm only.
A) arms and shoulders.
When the patellar reflex is elicited, the quadriceps muscles contract, but the hamstrings, their antagonists, relax. This relaxation is called
A) reciprocal inhibition.
B) polysynaptic.
C) crossed extension.
D) flexor withdrawal.
E) extrafusal inhibition.
A) reciprocal inhibition.