A&P Smartbook CH 14

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

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

C5 and C6

Which are characteristic of somatosensory pathways?

Each pathway transmits information to different regions of the brain.

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

T1-T11; two adjacent ribs

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

Each anterior root and its corresponding posterior root unite within the ______ to become a spinal nerve.

intervertebral foramen

A second-order neuron ______.

is an interneuron

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

lower

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

lumbar

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

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

pectoral girdle; upper limb

The initial component of a reflex arc is a(n) ______.

receptor

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

reflex

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

sacral

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

sensory and motor

The spinal cord in an adult is ______ than the vertebral canal that houses it.

shorter

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

spindle

A third-order neuron is also known as a

tertiary neuron

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

tertiary neuron or cerebellum

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

tract names include prefix indicating origin in cerebrum or brainstem

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

trunks

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 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 lumbar plexus is subdivided into a(n) ______ division and a(n) ______ division.

anterior; posterior

The receptors in somatosensory pathways ______.

are located in the joints, skeletal muscles, and skin

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

The anterior corticospinal tracts innervate ______.

axial skeletal muscle

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

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

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

Spinal reflexes ______ require the involvement of the brain.

do not

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

dorsal

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

excites or inhibits

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

extends to the spinal cord or brainstem

Match the reflex with its action. biceps reflex triceps reflex cremasteric reflex patellar reflex plantar reflex

-flexes elbow -extends elbow -elevates testis -extends knee -flexes toes

Match the reflex with the correct description. Instructions SPINAL REFLEX VISCERAL REFLEX POLYSYNAPTIC REFLEX IPSILATERAL REFLEX

-The integration center in this type of reflex is the spinal cord. -A gland may be the effector in this type of reflex. -This reflex includes one or more interneurons. -The receptor and effector in this reflex are located on the same side of the body.

Match the reflex with the correct description. spinal reflex visceral reflex polysynaptic reflex ipsilateral reflex

-The integration center in this type of reflex is the spinal cord. -A gland may be the effector in this type of reflex. -This reflex includes one or more interneurons. -The receptor and effector in this reflex are located on the same side of the body.

There are ______ pairs of spinal nerves.

31

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

42 and 45

In which reflex does the elbow flex?

Biceps reflex

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

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

Match the anatomical components of primary or first-order neurons of somatosensory pathways with their locations. Axons Cell Bodies Dendrites

PRIMARY NEURON-project to secondary or second-order neurons in the CNS. SECONDARY NEURON-posterior root ganglia of spinal nerves, sensory ganglia of cranial nerves. TERTIARY-part of a stimulus-specific receptor.

An ______ reflex is one that is developed after birth.

acquired

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

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

below

Spinal nerves contain axons of ______.

both motor and sensory neurons

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

brachial

The nerve plexus that supplies the arm is the ______ plexus.

brachial

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

Cell bodies of upper motor neurons are located in the ______.

cerebral cortex

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

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

rami

A posterior funiculus lies between the ______ gray horns on the posterior side of the cord and the posterior median sulcus.

posterior

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

posterior funiculus

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

primary and secondary

A first-order neuron is also known as a _____ neuron.

primary neuron

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