Nervous system

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

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

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

C5-T1

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 nerves emerging from a sacral plexus innervate the ______ region, pelvis, perineum, posterior thigh, and almost all of the ______.

gluteal; leg and foot

Sensory nervous system pathways transmit ______.

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

Motor pathways in the nervous system transmit ______.

information from the central nervous system to muscles or glands; descending

In terms of their functional classification in sensory pathways, secondary and tertiary neurons are ______, and primary neurons are sensory neurons.

interneurons

In a withdrawal reflex, ______ receives sensory information and stimulates motor neurons to direct ______ muscles to contract in response.

interneurons; flexor

At each ______ foramen, the dura mater extends between adjacent vertebrae and fuses with the connective tissue layers that surround the spinal nerves.

intervertebral

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

intervertebral foramen

When both the receptor and effector organs of a reflex are on the same side of the spinal cord, the proper term is ______.

ipsilateral

A second-order neuron ______.

is an interneuron

A third-order neuron ______.

is an interneuron;; it carries the signal the rest of the way to the cerebral cortex

In the spinal cord, the gray matter may be subdivided into the following components: anterior, posterior, and________________ horns, and the gray commissure

lateral

The musculocutaneous nerve arises from the ______ cord of the brachial plexus.

lateral

In the foot, the tibial nerve splits into the ______ plantar nerves, which innervate the plantar muscles of the foot.

lateral and medial

When you step on a jellyfish with your right foot, the ______ side of your brain sends the impulse to lift your right foot.

left

The ______ enlargement of the spinal cord contains axons that extend beyond the conus medullaris, innervating the lower limbs.

lumbosacral

The ulnar nerve arises from the ______ cord of the brachial plexus and descends along the medial side of the arm.

medial

The median nerve is formed from branches of the ______ cords of the brachial plexus.

medial and lateral

The ulnar nerve wraps posterior to the ______ of the humerus and then runs along the ulnar side of the forearm.

medial epicondyle

The spinal cord has two longitudinal depressions. These are the posterior ______ and the anterior ______.

median sulcus; median fissure

The spinal cord is protected and encapsulated by spinal cord meninges, which are continuous with the cranial ______.

meninges

Spinal nerves are considered ______ nerves because they contain both motor and sensory axons

mixed

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

monosynaptic

Name the type of reflex arc where the sensory axons synapse directly on the motor neurons, whose axons project to the effector.

monosynaptic

The simplest of all reflexes is the ________ reflex.

monosynaptic

Multiple anterior rootlets arise from the spinal cord and merge to form a single anterior root, which contains ______ axons only.

motor

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

Sensory ______ in the posterior horns contain interneuron cell bodies.

nuclei

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

nuclei or nucleus

Impulses from lower motor neurons _______ skeletal muscle.

only stimulate or excite

Deep to the subarachnoid space, is a delicate, innermost meningeal layer composed of elastic and collagen fibers. This layer is known as the ______

pia mater

he spinal meninges consist of the ____________ mater, _____________ mater, and ____________ mater. (List superficial to deep.)

pia, arachnoid, and dura mater

The tibial nerve travels in the posterior compartment of the leg, where it supplies the ______ of the foot and the toe flexors.

plantar flexors

The Golgi tendon reflex is a ______ reflex that prevents skeletal muscles from tensing excessively.

polysynaptic

Just superior to the ______, the two divisions of the sciatic nerve split into two nerves.

popliteal fossa

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

rami

Additional rami, called the ______, are also associated with spinal nerves.

rami communicantes

A phenomenon in which pain or discomfort from one organ is mistakenly referred to a dermatome is called ______.

referred visceral pain

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

The longest nerve in the body is the ______ nerve.

sciatic

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 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

A dermatome is a specific segment of ______ supplied by a single spinal nerve.

skin

Interneurons of a reflex arc are located in the ______.

spinal cord

Motor axons in a spinal nerve originate in the ______.

spinal cord

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

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

spindle

The dura mater provides ______ to the spinal cord.

stability

A hyperactive reflex refers to an abnormally ______ response.

strong

Deep to the arachnoid mater is the ______ space, which is a real space filled with ______ fluid.

subarachnoid space; cerebrospinal fluid

Golgi tendon organs are nerve endings located within ______ near a muscle-tendon junction.

tendons

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

A neural pathway consists of ______.

tract and a nucleus

The axons within each white matter funiculus are organized into smaller structural units called ______.

tracts

Each set of rami communicantes extends between the spinal nerve and a ball-like structure called the sympathetic ______.

trunk ganglion

A stretch reflex is a simple monosynaptic reflex involving ______.

two neurons

The gray commissure primarily contains ______ axons and serves as a communication route between the right and left sides of the ______ matter.

unmyelinated; gray

The cell bodies of ______ motor neurons are found in the cerebral cortex.

upper

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

The appendix is innervated by axons from the ______ regions of the spinal cord, so appendicitis typically causes referred visceral pain to the ______ dermatome in the umbilicus region rather than in the abdominopelvic region of the appendix itself.

T10; T10

The anterior rami of the ______ region of the spinal cord do not contribute to nerve plexuses.

T2-T12

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 musculocutaneous nerve innervates the ______ arm muscles that flex the humerus and ______ the forearm.

anterior; flex

The median nerve innervates most of the ______ forearm muscles, the thenar muscles, and the lateral two ______.

anterior; lumbricals

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

anterior; posterior

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 receptors in somatosensory pathways ______.

are located in the joints, skeletal muscles, and skin

The epidural space contains ______ connective tissue, ______, and adipose connective tissue.

areolar; blood vessels

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

Each lateral funiculus contains both ______ and ______ tracts.

ascending, descending

The rami communicantes contain axons associated with the ______ nervous system.

autonomic

The ______ of the spinal cord contains the neurons that innervate the upper limbs.

cervical enlargement

Sensory/ascending tracts

conduct nerve impulses toward the brain

When the sensory impulses from a receptor organ cross over through the spinal cord to activate effector organs in the opposite limb, the proper term for this phenomenon is ______.

contralateral

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

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

The tapering inferior end of the spinal cord is called the ______.

conus medullaris

When viewed in cross section, the spinal cord is roughly ______, but slightly ______ both posteriorly and anteriorly.

cylindrical; flattened

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 ______ space lies between the dura mater and the periosteum covering the inner walls of the vertebra.

epidural

Impulses from upper motor neurons _______ lower motor neurons.

excite or inhibit

The radial nerve innervates the forearm ______ and the posterior forearm muscles.

extensors

The white matter of the spinal cord is ______ to the gray matter.

external

The epidural space contains

fat

All spinal nerves except ______ innervate a segment of skin, and so each of these nerves is associated with a dermatome.

C1

Match the reflex with the correct description: 1. spinal reflex 2. Visceral reflex 3. Polysynaptic reflex 4. Ipsilateral reflex

1. The integration center in this type of reflex is the spinal cord. 2. A gland may be the effector in this type of reflex. 3. This reflex includes one or more interneurons. 4. The receptor and effector in this reflex are located on the same side of the body.

The spinal cord is associated with ______ pairs of spinal nerves.

31

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

42 and 45

a. white matter b. gray matter c. posterior median sulcus d. anterior median fissure e. spinal nerve

In the picture of the spinal cord, match the structures with the indication in the diagram.

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

1. Stimulus activates receptor 2. Nerve impulse travels through sensory neuron to the spinal cord 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 Motor neuron transmits nerve impulse to effector 5. Effector responds to impulse from motor neuron Effector responds to impulse from motor neuron

Match the steps in a reflex arc with its description.

a. epidural space B. dura mater c. spinal cord d. body of vertebra

Match the structure or space with the letter indicated.

a. dorsal root b. ventral root c. arachnoid mater d. dura mater e. pia mater

Match the structure with the indication on the diagram of the spinal cord.

a. tertiary sensory neuron b. secondary sensory neuron c. primary sensory neuron d. upper motor neuron e. lower motor neuron.

Match the types of neurons provided in the figure to their letters.

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

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 sensations.

______ sensory nuclei receive information from sensory receptors, such as pain or pressure receptors in the skin.

Somatic

Lateral horns are found in the ______ parts of the spinal cord only.

T1-L2

The ______ horns primarily house the cell bodies of somatic motor neurons.

anterior

The ______ ramus is the larger of the two main branches of a spinal nerve.

anterior

The tibial nerve is formed from the ______ divisions of the sciatic nerve.

anterior

After splitting from the spinal nerve, the anterior ramus divides into multiple other branches, which innervate the ______ portions of the trunk, the upper limbs, and the lower limbs.

anterior and lateral

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

anterior rami

The lateral cord of the brachial plexus is lateral to the axillary artery and is formed from the ______ divisions of the superior and middle trunks; thus, it contains portions of nerves ______.

anterior; C5-C7

The medial cord is medial to the axillary artery and is formed by the ______ division of the inferior trunk; it contains portions of nerves ______.

anterior; C8-T1

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

below

Inferior to conus medullaris, nerve roots collectively called the ______ project inferiorly from the spinal cord.

cauda equina

The gray commissure is a horizontal bar of gray matter that surrounds a narrow ______.

central canal

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

centrally; butterfly

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

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 ______ from the brain to the spinal cord.

descending tracts

A first-order neuron ______.

detects a stimulus and transmits a signal to the spinal cord or brainstem

The phrenic nerve travels through the thoracic cavity to innervate the ______.

diaphragm

The ______ ramus is the smaller of the two main branches of a spinal nerve.

posterior

The radial nerve arises from the ______ cord of the brachial plexus.

posterior

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

posterior

Which spinal nerve rami do not form plexuses?

posterior rami

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

primary

The neurons in sensory pathways are termed ______.

primary, secondary, and sometimes tertiary neurons

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/conscious; involuntary/subconscious