Chapter 14 Learnsmart

the left and right sacral plexuses are formed from the __ rami of spinal nerves __ and are located immediately inferior to the lumbar plexuses

anterior, L4-S4

the left and right lumbar plexuses are formed from the __ rami of spinal nerves L1-L4 located lateral to the L1-L4 vertebrae and along the __ muscle in the posterior abdominal wall

anterior, psoas major

pathways that transmit sensory impulses are also called __ pathways because the information travels from sensory receptors superiorly through the spinal cord to the brain

ascending

some of the individual tracts conduct sensory impulses as __ from the spinal cord to the brain

ascending tracts

match the anatomical components of primary or first order neurons of somatosensory pathways with their locations

axons: project to secondary or second order neurons in the CNS cell bodies: posterior root ganglia of spinal nerves, sensory ganglia of cranial nerves dendrites: part of a stimulus-specific receptor

match the reflex with its action

biceps reflex: flexes elbow triceps reflex: extends elbow cremasteric reflex: elevates testis patellar reflex: extends knee plantar reflex: flexes toes

a hyperactive reflex may indicate damage somewhere in either the __

brain or spinal cord

the gray matter in the spinal cord is __ located, and its shape resembles a letter H or a __

centrally, butterfly

the names of the principal nerve plexuses are the __ plexuses, __ plexuses, lumbar plexuses, and sacral plexuses

cervical, brachial

when a stimulus results in the stretching of a muscle, that muscle reflexively __

contracts

when decussation occurs, information is processed on the opposite side of the brain or __ compared to where the information is coming from or the destination of the impulse

contralaterally

each brachial plexus is composed of anterior rami, trunks, divisions, and __ when examined from a medial to lateral perspective

cords

when a golgi tendon organ is activated, nerve impulses in the golgi tendon organ signal __ in the spinal cord, which in turn __ the actions of the motor neurons

interneurons, inhibit

the term __ means the same side; contralateral means the opposite side

ipsilateral

a second-order neuron __

is an interneuron

a third-order neuron __

is an interneuron

the white matter region on each lateral side of the spinal cord is the __

lateral funiculus

the cell bodies of __ motor neurons are found within brainstem cranial nerve nuclei or in the anterior horn of the spinal cord

lower

five major terminal branches emerge from the three cords of the brachial plexus: the axillary, ulnar, radial, __, and __ nerves

median, musculocutaneous

all upper motor neurons of the corticospinal tracts pass through the __

medulla oblongata

spinal nerves are considered __ nerves because they contain both motor and sensory axons

mixed

a spinal nerve contains __ axons

motor and sensory

the spinal nerves connect the central nervous system to __, __, and receptors

muscles, glands

the central nervous system forms primarily from the embryonic __

neural tube

a collection of neuron cell bodies within the central nervous system is called a __

nucleus

impulses from lower motor neurons __ skeletal muscle

only stimulate or excite

the type(s) of sensory information transmitted along the anterolateral pathway include __

pain and temperature, crude touch and pressure

upon reaching the axilla, the posterior and anterior divisions of the brachial plexus converge to form three cords, the medial, lateral and __ cords

posterior

a first-order neuron is also know as a __ neuron

primary

from the list below, identify the type(s) of sensory information transmitted along the spinocerebellar pathway

proprioceptive body movements, proprioceptive limb position

awareness of the stimulus occurs after the __ action has been completed, in time to correct or avoid a potentially dangerous situation

reflex

the spinal cord and spinal nerves are responsible for __, which are our quickest reactions to a stimulus

reflexes

match the tract with the functions for which it is responsible

reticulospinal: unskilled, automatic movements related to posture and maintaining balance rubrospinal: precise, discrete movements and tone in flexor muscles of the limbs tectospinal: respond to visual and auditory stimuli by controlling positional changes of upper limbs, eyes, head, and neck vestibuolospinal: muscular activity that helps maintain balance during sitting, standing, and walking

a second-order neuron is also known as a __ neuron

secondary

identify the correct statement(s) describing the relationships of primary, secondary, and tertiary neurons in somatosensory pathways

secondary neurons synapse with tertiary neurons in the thalamus when transmitting conscious sensation

the tibial nerve conducts __ impulses from the skin covering the sole of the foot

sensory

the spinal cord in an adult is __ than the vertebral canal that houses it

shorter

where do axons of secondary neurons of the anterior spinocerebellar tract decussate?

some axons decussate in the spinal cord at the level of entry of the primary neuron, some axons decussate in the pons, some axons do not decussate

a hypoactive reflex may indicate damage to a segment of the __, or it may suggest muscle disease or damage to the __ junction

spinal cord, neuromuscular

match the reflex with the correct description

spinal reflex: the integration center in this type of reflex is the spinal cord visceral reflex: a gland may be the effector in this type of reflex polysynaptic reflex: this reflex includes one or more inteneurons ipsilateral reflex: the receptor and effector in this reflex are located on the same side of the body

a hyperactive reflex refers to an abnormally __ response

strong

deep to the arachnoid mater is the __ space, which is a real space with __ fluid

subarachnoid, cerebrospinal

in sensory pathways, secondary neurons synapse with cell bodies of __ neurons

tertiary

the cell bodies of __ motor neurons are found in the cerebral cortex

upper

identify the anatomical component of motor pathways

upper and lower motor neurons

the left and right brachial plexuses are networks of nerves that supply the __

upper limb

the __ tracts originate within vestibular nuclei of the brain and regulate muscular activity related to maintaining balance during sitting, standing, and walking

vestibulospinal

pathways that transmit information from internal organs to the brain are called __, whereas pathways that transmit information from proprioceptors and the body wall are called __

viscerosensory, somatosensory

identify the 4 correct statements about the neurons of the posterior funiculus-medial lemniscus pathway

1. secondary neurons transmit sensory information to the thalamus with the other axons of the trigeminothalamic tract 2. tertiary neurons extend from the thalamus to the primary somatosensory cortex 3. primary neurons that synapse with secondary neurons in the nucleus gracilis ascend within the fasciculus gracilis 4. primary neurons that synapse with secondary neurons in the nucleus cuneatus ascend within the fasciculus cuneatus

match the steps in a reflex arc with its description

1. stimulates activates receptor 2. nerve impulse travels through sensory neuron to the spinal cord 3. nerve impulse is processed in the integration center by interneurons 4. motor neuron transmits nerve impulse to effector 5. effector responds to impulse from motor neuron

there are __ pairs of spinal nerves

31

the spinal cord contains __ pairs of cervical nerves, 12 pairs of thoracic nerves, __ pairs of lumbar nerves, __ pairs sacral nerves, and 1 pair of coccygeal nerves

8, 5, 5

one important branch of the cervical plexus is the phrenic nerve, which is formed primarily from the __ nerve and some contributing axons from __

C4, C3 and C5

by the sixth fetal month, the spinal cord is at the level of the __ vertebra, while a newborn's spinal cord ends at about the __ vertebra

S1, L3

a reflex arc always begins at a receptor in the __, communicates with the __, and ends at a peripheral effector, such as a muscle or gland cell

PNS, CNS

lateral horns are found in the __ parts of the spinal cord only

T1-L2

nerve plexuses are organized such that axons from each __ extend to body structures through several different branches

anterior ramus

a neural pathway consists of __

a tract and a nucleus

each term on the left is descriptive of nervous system pathways; match term with its meaning

decussate: axons in a tract cross over from one side of the body to the other along the tract paired tracts: for every tract on the left side of the cns there is a corresponding tract on the right side of the cns; each tract innervates structures on only side of the body neurons in series: from origin to destination, sensory pathways consist of three of two neurons, whereas motor pathways consist of two neurons

pathways that transmit motor impulses are also called __ pathways because the information travels inferiorly from the brain, through the spinal cord, to muscles or glands

descending

some individual fasciculi conduct motor impulses as __ form the brain to the spinal cord

descending (motor) tracts

primary motor neurons of the __ motor pathway originate in the primary motor cortex, whereas primary motor neurons of the __ motor pathway originate in the brainstem

direct, indirect

the two main branches of a spinal nerve are the ventral and __ rami

dorsal

the spinal meninges consist of the __ mater, __ mater, and __ mater (list superficial to deep)

dura, arachnoid, pia

which are characteristic of somatosensory pathways?

each pathway transmits information to different regions of the brain

nervous system pathways conduct __

either sensory information or motor impulses.

the superficial fibular nerve innervates the lateral compartment muscles of the leg, specifically those that __ and the weak plantar flexors

evert the foot

impulses from upper motor neurons __ lower motor neurons

excite or inhibit

in a clinical setting, a reflex response may be normal, hyperactive or __

hypoactive

receptors that transmit sensory information by way of the posterior funiculus-medial lemniscus pathway, regarding limb position, precise pressure, vibration, and discriminative touch, originate __

in the limbs, trunk, neck, and posterior head

the coccygeal region is the most __ part of the spinal cord

inferior

as a result of the golgi tendon flex, the motor neurons that cause the muscle contraction are __

inhibited

in terms of their functional classification in sensory pathways, secondary and tertiary neurons are __, and primary neurons are sensory neurons

interneurons

impulses transmitted through the direct, pyramidal or corticospinal pathway, pass directly from upper to lower motor neurons (no __ involved) and are responsible for __ control of skeletal muscles

interneurons, conscious

in a withdrawal reflex, __ receive sensory information and stimulate motor neurons to direct __ muscles to contract in response

interneurons, flexor

the dendrites and cell bodies of secondary or second order neurons of somatosensory pathways are found within either the posterior horn of the spinal cord of within a brainstem nucleus, whereas the axon of a secondary neuron projects either to the __ or cerebellum

thalamus

in general, secondary neurons in somatosensory pathways that transmit conscious sensations project to the __, and those that transmit unconscious proprioception project to the __

thalamus, cerebellum

white matter on each side of the cord is also partitioned into __ regions, each called a __

three, funiculus

the sciatic nerve is actually composed of two divisions wrapped in a common sheath; what are the two divisions?

tibial and common fibular

features of the descending projection tracts of motor pathways include __

tract names include prefix indicating origin in cerebrum or brainstem

the axons within each white matter funiculus are organized into smaller structural units called __

tracts