AP Chapter 13

Plexus

A network of nerves is known as a

Which division of the peripheral nervous system (PNS) detects stimuli and carries them to the CNS? A sensory B motor C autonomic D sympathetic

A sensory

sacral plexus

Arises from L4-S4 - Serves the buttock, lower limb, pelvic structures, and perineum

Which division detects stimuli of the general senses and special senses? A Visceral motor division (ANS) B Somatic sensory division C Visceral sensory division D Somatic motor division

B Somatic sensory division

Which cranial nerve is NOT involved in eye movement? A Oculomotor Nerve (III) B Abducens Nerve (VI) C Vestibulocochlear nerve (VIII) D Trochlear nerve (IV)

C Vestibulocochlear nerve (VIII)

brachial plexus

C5-T1

Which of the following houses motor neurons? A central canal of the spinal cord B posterior root of spinal cord C posterior root ganglion D anterior root of spinal nerve

D anterior root of spinal nerve

Mixed nerves house: A sensory neurons only B motor neurons only C somatic neurons only D both sensory and motor neurons

D both sensory and motor neurons

What is the outermost connective tissue covering of a nerve? A. endoneurium B perineurium C epimysium D epineurium

D epineurium

flexion (withdrawal) reflex

Determine the polysynaptic reflex from this list of examples: jaw-jerk reflex, patellar (withdrawal) reflex, flexion (withdrawal) reflex, simple stretch reflex

Cervical Plexus (C1-C5)

During a boxing match, Sammy was hit on the side of the neck. He stopped breathing temporarily due to damage to the:

Merkel cell fibers have the finest spatial resolution of any of the skin mechanoreceptors. They primarily detect touch stimuli such as form and texture. Tactile corpuscles transmit discriminative touch stimuli, although their resolution is not as fine. Hair follicle receptors respond to stimuli that cause the hair to bend. Together with the Merkel cell fibers and tactile corpuscles, hair follicle receptors detect various types of touch to inform us of the world around us.

Explain how hair follicle receptors complement the function of tactile corpuscles and Merkel cell fibers

A monosynaptic reflex involves only a single synapse within the spinal cord between the sensory and motor neurons. A polysynaptic reflex involves multiple synapses.

Explain the difference between a monosynaptic reflex and a polysynaptic reflex.

A ramus is either an anterior or a posterior branch of a spinal nerve. The anterior rami of the cervical, lumbar, and sacral nerves come together and merge to form complicated networks of nerves called nerve plexuses. The axons of each spinal nerve cross over one another to enter different nerve plexuses.

Explain the difference between a ramus and a plexus.

Upper motor neurons, located in the primary motor cortex of the cerebrum, stimulate lower motor neurons. Lower motor neurons innervate skeletal muscle fibers within a single skeletal muscle. Lower motor neurons initiate a muscle contraction. Groups of lower motor neurons that innervate the same muscle are called motor neuron pools.

Generalize the role of the lower motor neuron in motor control.

Which cranial nerve is generally thought of as a mixed nerve? A Hypoglossal nerve (XII) B Vestibularcochlear nerve (VIII) C Accessory nerve (XI) D glossopharyngeal nerve (IX)

Glossopharyngeal nerve (IX)

extends

In the crossed-extension reflex, if the right leg flexes, then the left leg:

The cranial nerves that generally considered sensory are the olfactory (1), optic (II) and vestibulocochlear (VIII) nerves

List cranial nerves and their corresponding Roman numerals that are generally considered sensory nerves.

lower motor neurons

Motor neurons pools consist of:

olfactory bulb

Name this part

False

Receptive field maps show the regions of skin and the spinal nerve that supplies somatic sensation to them.

stimuli

Reflexes are programmed, automatic, and rapid responses to ?

rapidly adapting receptors

Sensory receptors that adapt to stimuli after a certain period of time are:

PNS sensory neurons

Sensory transduction occurs in __________.

Ulnar nerve

Striking the "funny bone" is actually stimulation of (or injury to) the ________.

False Olfactory nerve (I)

The first pair of cranial nerves is the optic nerve (I)

False The hypoglossal nerve is not involved

The hypoglossal nerve (XII) and glossopharyngeal nerve (IX) are both involved in taste sensation.

glossopharyngeal nerve (IX) or vagus nerve (X)

The inability to produce a gag reflex could indicate a problem with the:

Interoceptor

The stretch of a full urinary bladder is detected by a(n):

What is cranial nerve VIII?

Vestibulocochlear nerve (auditory nerve)

interneurons

What connects the upper motor neurons to lower motor neurons

What connective tissue sheath wraps the axon of a neuron?

endoneurium

The vagus nerve is represented by Roman numeral:

x

trochlear nerve

Which nerve is cranial nerve IV?

You feel a mosquito land on your arm. This stimulus is carried to the CNS by the: A somatic sensory division B visceral sensory division C visceral motor division (ANS) D somatic motor division

A Somatic sensory division

The cranial nerves that have neural connections with the tongue include all of the following EXCEPT: A Trochlear nerve (IV) B Trigeminal nerve (V) C Facial nerve (VII) D Glossopharyngeal nerve (IX)

A Trochlear nerve

The upper motor neurons stimulate the lower motor neurons. The lower motor neurons will be unable to stimulate affected skeletal muscles to contract. This patient will experience weakness or paralysis of the affected muscles and loss of reflexes since the lower motor neurons are damaged.

A patient sustained an injury to the lower motor neurons when a board fell on his back at a construction site. The upper motor neurons are intact and undamaged. Determine the effect, if any, on motor control.

Monosynaptic reflex

A reflex with a single synapse between the sensory and motor neurons within the spinal cord is known as a __________.

5 mm

A region of skin has a great number of sensory neurons, and each neurons has a relatively small receptive field. The two-point discrimination threshold for this skin region might be:

the relative size of receptive fields

A test known as two-point discrimination threshold measures:

Ms. Parker has damage to the sensory root of the facial nerve (VII). Which of the following symptoms matches this information? A inability to elevate the mandible B inability to swallow C inability to taste D inability to smell

C inability to taste

Loss of balance and equilibrium can indicate damage to the: A hypoglossal nerve (XII) B accessory nerve (XI) C Vestibulocochlear nerve (VIII) D Trochlear nerve (IV)

C. Vestibulocochlear nerve (VIII)

The reflex arc begins with 1 the detection of a stimulus by a sensory receptor in the PNS. 2 The stimulus is delivered to the CNS where integration occurs. 3 The rapid motor response is delivered to the effector

Outline the three-step sequence of a reflex arc.

An inability to swallow indicates a problem with the: A accessory nerve (XI) or hypoglossal nerve (XII) B olfactory nerve C trochlear nerve (IV) or abducens nerve (VI) D trigeminal nerve (V) or glossopharyngeal nerve (IX)

D trigeminal nerve (V) or glossopharyngeal nerve (IX)

The sympathetic nervous system and parasympathetic nervous system are divisions of the: A somatic sensory division B somatic motor division C visceral sensory division D visceral motor division (ANS)

D visceral motor division (ANS)

The sacral plexus forms from the anterior rami of spinal nerves L4-S4. Rami are mixed nerves, housing both sensory, and motor neurons. The sciatic nerve is the largest nerve of this plexus. It splits into two main branches, the tibial nerve and the common fibular nerve. The tibial nerve divides into its terminal branches which serve the muscles and skin of the foot at the level of the medial malleolus of the tibia. Since Dan reported loss of sensation in his feet, the sensory neurons of the sciatic nerve must have sustained injury after his accident.

Dan injured the spinal nerves emerging from the lower lumbar and sacral region of the spinal cord during a horse-riding accident. After his injury, he reported numbness in his feet. Explain the connection between the loss of sensation he has described and the plexus responsible for serving this area.

Some sensory receptors, known as rapidly adapting receptors, respond rapidly with high intensity to a stimulus. While these receptors are important for the initial detection of stimuli, they ignore ongoing stimuli. Thus, they will cease to create action potentials even with a continued stimulus. This concept is known as adaptation as it relates to sensory receptors. Tactile corpuscles and lamellated corpuscles are rapidly adapting receptors.

Define adaptation as it relates to sensory function. What types of mechanoreceptors adapt?

The steps of sensory transduction are as follows: 1 Before a stimulus arrives, the ion channels in the axolemma of the PNS sensory neuron are closed 2 When a stimulus arrives, mechanically gated sodium ion channels open. Sodium ions enter the axoplasm, causing a temporary depolarization referred to as receptor potential. 3 If enough sodium ions enter that the membrane potential reaches threshold, voltage-gated sodium ion channels open. An action potential is triggered and it is propagated along the axon to the CNS

Describe the steps of sensory transduction when a touch receptor in the skin is activated.

The anterior rami of the cervical, lumbar, and sacral spinal nerves come together and merge to form complicated networks of nerves called nerve plexuses. The axons of each spinal nerve cross over one another to enter different nerve plexuses. For this reason, the muscles supplied by a single branch of a nerve plexus are often served by two or more different spinal nerves. This works to our advantage, as it means that injury to one spinal nerve does not completely cut off motor or sensory innervation to the body part.

Describe the structure of a nerve plexus and explain the advantage of this structure to its function

The two main divisions of the peripheral nervous system (PNS) are the sensory (afferent) division and motor (efferent) division. The sensory division consists of sensory (afferent) neurons that detect stimuli and bring them to the central nervous system (CNS). The motor division consists of motor (efferent) neurons that carry out the motor functions of the nervous system. Both the sensory and motor divisions can be further classified.

Discuss the functions of the two main divisions of the peripheral nervous system (PNS)

The sacral plexuses stem from the anterior rami of spinal nerves L4-S4 and innervate structures of the pelvis, the gluteal region, and the lower limb. The sciatic nerve, the largest and longest nerve of the body, is a member of this plexus.

Discuss the spinal nerves that contribute to the sacral plexuses and the body region(s) served.

In the two-point discrimination threshold test, two stimuli (such as calipers or application sticks) are placed close together on the skin. The calipers are moved increasingly apart until the subject can fell two distinct points. Different regions of the skin contain neurons with receptive fields of varying size. The more neurons that populate an area of skin, the smaller the receptive field will be. Thus, the smaller the receptive field, the smaller the distance between the two points that a subject can detect using the two-point discrimination threshold test.

How does the two-point discrimination threshold demonstrate, the size of receptor fields in the skin?

Twelve pairs

How many cranial nerves transmit information to and from the brain?

Cranial nerve XII

Hypoglossal nerves is which number?

The oculomotor nerve (III), trochlear nerve (IV), and abducens nerve (VI) are the three pairs of cranial nerves that control eye movement. The oculomotor nerve moves the eyes superiorly, medially, and inferiorly, and inferolaterally. The trochlear nerve innervates the superior oblique muscle of each eye while the abducens nerve abducts the gaze when it turns the eyes laterally.

Identify and name the cranial nerves responsible for eye movement. Indicate the function of each cranial nerve identified.

The epineurium holds together the structures that make up a nerve. Within the nerve, axons are bundled into fascicles held together and supported by a connective tissue sheath known as the perineurium. Each axon within the fascicle is surrounded by its own connective tissue sheath known as the endoeurium.

List and describe the connective tissue sheaths that make up a nerve

The five major nerves of the brachial plexuses are the axillary nerves, radial nerves, musculocutaneous nerves, median nerves, and the ulnar nerves.

List the five major nerves of the brachial plexuses.

False lower motor neurons receive impulses from the upper motor neurons and connect the spinal cord and brain stem to the muscle fibers.

Motor control is initiated by lower motor neurons and transmitted to upper motor neurons by interneurons situated within the CNS

referred pain

Ms Carroll wen to her doctor's office with pain in her right shoulder blade and learned she was having a gallbladder attack. You're not surprised to hear about the unusual location of her pain since it is known as

sensory tran

Olfactory receptors depolarize in response to an odorant, turning a stimulus into an electrical signal. This conversion is known as

The steps of a simple stretch reflex are as follows: 1 The simple stretch reflex is initiated when an external force stretches the muscle. 2 Muscle spindles detect the stretch, and primary and secondary afferents transmit an action potential to the spinal cord. 3 In the spinal cord, the sensory afferents synapse on an alpha motor neuron and trigger an action potential. 4 The alpha motor neuron stimulates the muscle to shorten, and it returns to its optimal length.

Outline the steps to a simple stretch reflex.

The affected nerve if the tongue is bent or slanted during a stroke is the hypoglossal nerve (XII). The hypoglossal nerve is a motor nerve responsible for moving the tongue. It innervates most of the intrinsic and extrinsic muscles of the tongue.

People suspected of having a stroke can be asked to stick their tongues straight out. A slanted or somewhat bent tongue may be just one indicator of stroke. Determine the cranial nerve affected if the tongue is bent or slanted and identify the nerve as sensory, motor, or mixed. Describe the function of this nerve.

eye

Photoreceptors are found only in the

3 Upper motor neurons in the premotor cortex select a motor program 5 The basal nuclei enable the thalamus to stimulate upper motor neurons of the primary cortex. 1 Upper motor neurons stimulate lower motor neurons 4 Lower motor neurons stimulate a skeletal muscle to contracts 2 Sensory information is relayed back to the cerebellum so movement can be modified if needed.

Place the following steps in order for motor control. 1 Upper motor neurons stimulate lower motor neurons 2 Sensory information is relayed back to the cerebellum so movement can be modified if needed. 3 Upper motor neurons in the premotor cortex select a motor program 4 Lower motor neurons stimulate a skeletal muscle to contracts 5 The basal nuclei enable the thalamus to stimulate upper motor neurons of the primary cortex.

nociceptors

Potentially damaging stimuli that result in pain are selectively detected by ________.

Somatic motor neurons of the vagus nerve are responsible for triggering contractions of the muscles of the pharynx to produce the "gag" during the gag reflex. Thus, a person not be able to elicit a gag reflex if the vagus nerve is damaged.

Predict the impact on the gag reflex when a person has a damaged vagus nerve.

lumbar plexus is

T12-L4

The 12 pairs of cranial nerves are Olfactory (1), Optic (II), Oculomotor (III), trochlear (IV), Trigeminal (V), Abducens (VI), Facial (VII), Vestibulocochlear (VIII), glossopharyngeal (IX), vagus (X), accessory (XI), and hypoglossal (XII)

The 12 pairs of cranial nerves, in numerical order, with their corresponding Roman numerals.

Spinal nerve

The anterior root and posterior root fuse to form:

sciatic nerve

The longest and largest nerve in the body belongs to the sacral plexus and is known as the

cervical plexus

The phrenic nerve is a member of the:

False The thirty-one pairs of spinal nerves are mixed, having both a sensory and a motor aspect. Their motor fibers begin on the ventral part of the spinal cord at the anterior horns of the gray matter. The roots of their sensory fibers are located on the dorsal side of the spinal cord in the posterior root ganglia. When the motor and sensory fibers exit the spinal column through the intervertebral foramina and pass through the meninges, they join together to form the spinal nerves.

The posterior (dorsal) root of a spinal nerve and the posterior ramus are considered mixed nerves since they both carry sensory and motor information.

False When a muscle lengthens, the muscle spindle is stretched and its nerve activity increases. This increases alpha motor neuron activity, causing the muscle fibers to contract and thus resist the stretching. A secondary set of neurons also causes the opposing muscle to relax. The reflex functions to maintain the muscle at a constant length.

The simple stretch reflex employs mechanoreceptors known as Golgi tendon organs to detect the degree of stretch experienced by a muscle.

True

The somatic sensory division of the peripheral nervous system (PNS) carries stimuli from both general and special senses to the Central Nervous System (CNS)? True or False

a large-diameter, myelinated axon

The speed of nerve impulse transmission through the axon of a sensory neuron will be quickest in __________.

nuclei in the pons and medulla

Where does the motor portion of the facial nerve (VIII) originate?

False; The visceral efferent nervous system, supplies motor impulses to cardiac muscle, to smooth muscle, and to glandular epithelium.

The visceral motor division (ANS) controls the body's voluntary motor functions.

False Upper motor neurons (UMN) are located within the brain and brainstem and send their axons down the spinal cord to innervate lower motor neurons (LMN).

Upper motor neurons directly contact and stimulate skeletal muscle fibers to contract.

C referred pain

Visceral pain may be perceived as cutaneous pain, a phenomenon known as: A phantom limb pain B slowly adapting reception C referred pain D the receptive field

Proprioceptors

What are located in the musculoskeletal system where they detect the movement and position of a joint or body part

The lumbar nerve plexuses

What arises from the anterior rami of L1-L4 and innervates structures of the pelvis and lower limb.

Anterior ramus

What controls the movement of rectus abdominis, a skeletal muscle on the anterior surface of the body?

Oculomotor nerve

What cranial nerve is this?

Trigeminal nerve (V) as sensory; facial nerve (VII) as motor

What cranial nerves are involved in the sensory and the motor roles for the corneal blink reflex?

intercostal nerves

What do most of the anterior rami of the thoracic spinal nerves serve?

.They detect stimuli from the inside of the body, such as blood pressure, stretch of a full urinary bladder, and the body's temperature

What does interoreceptors do?

D Muscle spindles are found within tendons

What is NOT true of muscle spindles? A Muscle spindles are embedded within extrafusal muscle fibers? B The contractile poles of intrafusal fibers within muscle spindles are innervated by 𝛾-motor neurons. C Muscle spindles are receptors for the stretch reflex. D Muscle spindles are found within tendons

Abuducens

What is this called

Central Nervous System (CNS)

What part of the nervous system integrates and interprets information from PNS sensory neurons:

Golgi tendon reflex

What reflex causes muscle relaxation?

𝛼- motor neuron

What type of motor neuron stimulates skeletal muscle fibers to contract by the excitation-contraction mechanism?

lower motor neuron

What type of neuron contacts a muscle fiber and initiates a muscle contraction?

Mechnoreceptors

What type of sensory receptors are muscle spindles and Golgi tendon organs?

lamellated corpuscles

Which mechanoreceptor detects deep pressure?

Inflammation of the median nerves results in carpal tunnel syndrome. The median nerve runs down the middle of the arm and forearm. It serves the wrist and digital flexor muscles. In the hand, this nerve supplies some of the intrinsic hand muscles and skin over the anterior thumb, the second and third digits, and the lateral half of the fourth digit.

Which nerve of the brachial plexus becomes inflamed resulting in carpal tunnel syndrome? Explain what regions are served by this inflamed nerve.

cervical plexus includes the phrenic nerve

Which nerve plexus includes the phrenic nerve

Sacral Plexus (L4-S4)

Which nerve plexus includes the sciatic nerve

posterior (dorsal) root

Which of the following carries sensory information only? A posterior (dorsal) root B anterior root C posterior ramus Danterior ramus

crossed-extension reflex

Which of the following complements the flexion (withdrawal) reflex? Golgi tendon reflex, gag reflex, crossed-extension reflex, stretch reflex

C. Phrenic nerve

Which of the following does NOT belong to the brachial plexus? A musculocutaneous nerve B median nerve C phrenic nerve D ulnar nerve

B Neural integration of a reflex usually occurs in the PNS

Which of the following does NOT characterize a reflex? A A reflex is an automatic response to a stimulus. B Neural integration of a reflex usually occurs in the PNS C Reflexes require a stimulus to initiate a motor response D The motor response to a stimulus is rapid.

7 pairs of cervical spinal nerves

Which of the following is about the numbers of spinal nerves? 5 pairs of sacral spinal nerves 5 pairs of lumbar spinal nerves 7 pairs of cervical spinal nerves 12 pairs of thoracic spinal nerves

B detection by receptor and delivery of stimulus

Which of the following must occur first in a reflex arc? A delivery of motor response to effector B detection by receptor and delivery of stimulus C integration in the central nervous system (CNS) D transmission from the primary motor cortex

A mixed nerve would be the most devastating to damage as it contains both sensory and motor neurons. A damaged mixed nerve could potentially impair both sensation and movement to some degree. Sensory nerves contain only sensory neurons while motor nerves contain mostly motor neurons (with a small population of sensory neurons). Damage to a sensory nerve would only affect sensation while damage to a motor nerve primarily affect movement of specific muscles.

Which of the following would be most devastating to damage: motor nerve, sensory nerve, or mixed nerve. Explain

Brachial Plexus (C5-T1)

Which plexus provides motor and sensory innervation to the upper limb?

thermoreceptor

You wrap your hands around a warm cup of hot chocolate. This sensation is detected by a

cranial nerves and spinal nerves

____are two types of nerves found in the peripheral nervous system (PNS)

Bundles of axons within a nerve are known as __________.

fascicles

Pressure

mechanoreceptors might detect which of the following sensations? smell, pressure, temperature, light

Where is the motor response initiated?

motor areas of the brain

Which cranial nerve detects smell?

olfactory nerve (I)

dermatones

regions of the skin supplied by a spinal nerve for somatic sensation are known as: