Chapter 14 Nervous System Spinal Cord and Spinal Nerves

Primary motor neurons of the ______ motor pathway originating in the primary motor cortex, whereas primary motor neurons of the ______ motor pathway originate in the brainstem.

Direct, indirect

The left and right cervical plexuses are formed primarily by the anterior rami of spinal nerves ______.

C1-C4

The left and right cervical plexuses are located deep on each side of the neck, immediately lateral to cervical vertebrae ______.

C1-C4

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

Dorsal

Cervical nerves ______ unite to form the superior trunk of the anterior rami.

C5 and C6

Each brachial plexus is formed by the anterior rami of spinal nerves ______.

C5-T1

Which spinal nerves give rise to the inferior trunk of the brachial plexus?

C8-T1

Gray matter is primarily composed of ______.

Cell bodies and dendrites

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

Centrally, butterfly

The spinocerebellar pathway conducts information to the ______.

Cerebellum

A third-order neuron extends from the secondary neuron to the ______.

Cerebrum

In general, we are ______ of information transmitted along somatosensory pathways to the brain, and ______ of the information transmitted along viscerosensory pathways.

Conscious, unconscious, or unaware

During development, the individual vertebrae ______ spinal cord growth is complete.

Continue to grow after

Which statements correctly describe the corticospinal tracts?

Control appendicular and axial skeletal muscles

A descending motor tract of the direct pathway is the ______ tract.

Corticospinal

Axons of lower motor neurons of the corticobulbar tract form parts of the ______ nerves.

Cranial

Impulses traveling along the corticobulbar tracts control voluntary movement of ______.

Cranial and facial muscles

Identify the characteristic of the anterior corticospinal tracts.

Decussate in spinal cord

The spinal cord is partitioned into a ______ gray matter region and a ______ white matter region.

Deep, superficial

The gray matter of the spinal cord is dominated by the ______ and ______ of neurons.

Dendrites, cell bodies

Which are characteristic of somatosensory pathways?

Each pathway transmits information to different regions of the brain

Cremasteric reflex

Elevates testis

An impulse from an upper motor neuron ______ a lower motor neuron.

Excites or inhibits

The posterior division nerves of the sacral plexus tend to innervate muscles that ______ part of the ______ limb.

Extend; lower

Triceps reflex

Extends elbow

The axon of a primary neuron of a somatosensory pathway ______.

Extends to the spinal cord or brainstem

The nerves arising from the anterior division of the sacral plexus tend to innervate muscles that ______ parts of the lower limb.

Flex

Biceps reflex

Flexes elbow

Plantar reflex

Flexes toes

The white matter region on each lateral side of the spinal cord is the ______.

Lateral funiculus

The anterior rami of spinal nerves L1-L4 form the ______ plexus.

Lumbar

White matter that lies between the posterior gray horns is a ______.

Posterior funiculus

Cell bodies

Posterior root ganglia of spinal nerves, sensory ganglia of cranial nerves

In the spinocerebellar pathway, sensory information travels to the cerebellum along ______ neurons.

Primary and secondary

The neurons in sensory pathways are termed ______.

Primary, secondary, and sometimes tertiary neurons

Axons

Project to secondary or second-order neurons in the CNS

The types of sensory information transmitted along the posterior funiculus-medial lemniscus pathway include ______.

Proprioceptive, limb position

A third-order neuron is also known as a ______ neuron

Tertiary

In sensory pathways, secondary neurons synapse with the cell bodies of ______ neurons.

Tertiary

A secondary neuron extends from a primary neuron to the ______.

Tertiary neuron or cerebellum

In sensory pathways, secondary neurons synapse on cell bodies of tertiary neurons within the ______.

Thalamus

The sciatic nerve is actually composed of two divisions wrapped in a common sheath. What are the two divisions?

Tibial and common fibular

In sensory pathways, where do tertiary neurons conduct information?

To the cerebral cortex

Features of the descending projection tracts of motor pathways include ______.

Tracts names include prefix indicating origin in cerebrum or brainstem

Each brachial plexus is composed of anterior rami, trunks, divisions, and ______when examined from a medial to lateral perspective.

cords

Patellar reflex

extends knee

The anterior corticospinal tracts innervate ______.

A

Visceral reflex

A gland may be the effector in this type of reflex

There are ______ pairs of spinal nerves.

31

A typical adult spinal cord ranges between ______ centimeters (cm) in length.

42 and 45

An ______ reflex is one that is developed after birth.

Acquired

During development, the cranial and spinal nerves form primarily from ______.

Alar and basal plates

The cell bodies of lower motor neurons are in the ______.

Anterior horns of the spinal cord

A nerve plexus is a network of interweaving ______ of spinal nerves.

Anterior rami

The anterior rami (sometimes called roots) of the brachial plexus are simply the continuations of the ______ rami of spinal nerves ______.

Anterior, C5-T1

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 with the ______ muscle in the posterior abdominal wall.

Anterior, psoas major

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 receptors in somatosensory pathways ______.

Are located in the joints, skeletal muscles, and skin

Action potentials ______ the brain through sensory pathways.

Ascend to

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

Spinal nerve T12 is called a subcostal nerve because it arises ______ the ribs.

Below

In which reflex does the elbow flex?

Biceps reflex

The components of the ______ plexus extend laterally from the neck, pass superior to the first rib, and then continue into the axilla.

Brachial

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 reticulospinal tract is an example of a(n) ______ motor pathway.

Indirect

The lumbar part of the spinal cord is closest to ______.

Inferior thoracic vertebrae

Sensory nervous system pathways transmit ______.

Information from somatic and special sense receptors to the central nervous system

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

A third-order neuron ______.

Is an interneuron

A first-order neuron ______.

Is the first neuron to transmit sensory information from the periphery of the body to the brain

The spinal cord extends inferiorly from the brain through the foramen magnum, then through the vertebral canal, and ends at the level of the ______ vertebra.

L1

All upper motor neurons of the corticospinal tracts pass through the ______.

Medulla oblongata

A spinal nerve is classified as a ______ nerve.

Mixed

A stretch reflex is a ______ reflex that monitors and regulates skeletal muscle length.

Monosynaptic

A spinal nerve contains ______ axons.

Motor and sensory

Reflexes are rapid, automatic, involuntary reactions of ______ to a stimulus.

Muscles or glands

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 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

Dendrites

Part of a stimulus-specific receptor

Each brachial plexus innervates the ______ and the entire ______ of one side.

Pectoral girdle, upper limb

After leaving the intervertebral foramen, a typical spinal nerve almost immediately splits into branches, termed ______.

Rami

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

Which of the following is an indirect motor pathway?

Rubrospinal tract

The anterior rami of spinal nerves L4-S4 form the ______ plexus.

Sacral

The sciatic nerve originates from the ______ plexus.

Sacral

The longest nerve in the body is the ______ nerve.

Sciatic

A first-order neuron synapses with a ______ neuron.

Second-order

A second-order neuron is also known as a ______ neuron

Secondary

The posterior rami of spinal nerves tend to follow a ______ pattern as they innervate the deep muscles and skin of the neck and back.

Segmental

The posterior rami of spinal nerves tend to follow a ______ pattern as they innervate the deep muscles and skin of the neck and back. Multiple choice question. scattered

Segmental

The spinal cord and its attached spinal nerves are a pathway for ______ impulses.

Sensory and motor

A reflex arc is the neural wiring of a ______ reflex.

Single

In sensory pathways, tertiary neurons conduct information to a specific location of the primary ______ cortex.

Somatosensory

Stretch in a muscle is monitored by a stretch receptor called a muscle

Spindle

An impulse from a lower motor neuron ______ a skeletal muscle.

Stimulates or excites

The anterior rami of spinal nerves ______ are called intercostal nerves because they travel in the intercostal space sandwiched between ______.

T1-T11, two adjacent ribs

Spinal Reflex

The integration center in this type of reflex is the spinal cord

Spinal reflex

The integration center in this type of reflex is the spinal cord

Ipsilateral reflex

The receptor and effector in this reflex are located on the same side of the body

Polysnaptic reflex

This reflex includes one or more interneurons

There are five roots of anterior rami that unite to form the superior, middle, and inferior ______ in the posterior triangle of the neck.

Trunks

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

Motor pathways use a(n) ______ motor neuron and a(n) ______ motor neuron.

Upper, lower

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

Primary motor neurons of the direct motor pathway issue impulses for ______ control of skeletal muscles; primary motor neurons of the indirect motor pathway issue impulses for ______ control of skeletal muscles.

Voluntary, involuntary