Which of the following cranial nerves carries only sensory information?

olfactory

A purely sensory nerve, the olfactory nerve carries afferent impulses for the sense of smell.

What type of nerve fibers are found in the ventral ramus of a spinal nerve?

both sensory and motor

The ventral (motor) nerve roots and the dorsal (sensory) nerve roots merge as they leave the vertebral column to form the spinal nerve proper, a mixed nerve. The spinal nerve immediately branches into a small dorsal ramus (branch) and a larger ventral ramus, both of which are mixed nerves (meaning they contain both motor and sensory fibers).

The primary nerve that controls breathing is found in which nerve plexus?

cervical

The phrenic nerve arises from the cervical plexus. It supplies both motor and sensory fibers to the diaphragm, the main breathing muscle.

What parts of the brain ultimately plan and coordinate complex motor activities?

cerebellum and basal nuclei

The cerebellum and basal nuclei are the ultimate planners and coordinators of complex motor activities and are therefore at the top of the motor control hierarchy.

Which reflex is important for maintaining muscle tone?

stretch reflex

The stretch reflex is important for maintaining muscle tone (and thus muscle length) and adjusting it reflexively. It is most important in the large extensor muscles that sustain upright posture and in postural muscles of the trunk.

Hiccups could occur if there was irritation or damage to the ______.

motor branches of ventral rami associated with the C₃-C₅ region of the spinal cord

The ventral rami of spinal nerves contain motor fibers that originate from neuron soma found in the spinal cord. These efferent pathways activate the contraction of skeletal muscle. The phrenic nerve branches from this region and innervates the skeletal muscle of the diaphragm.

Damage to the ulnar nerve could result in the inability to ______.

flex the wrist

One action of the flexor carpi ulnaris muscle is wrist flexion. This muscle is innervated by the ulnar nerve.

A herniated lumbar disc could interfere with ______.

skin sensations from the lateral thighskin sensations from the medial thighadduction of the thighAll of the listed responses are correct.

The branches of lumbar plexus include the following nerves: femoral, obturator, lateral femoral cutaneous, iliohypogastric, ilioinguinal, and genitofemoral.

The brachial plexus can be palpated at the lower lateral border of the sternocleidomastoid muscle. Injury to the brachial plexus could cause weakness or paralysis to all of the following EXCEPT the ______.

sternocleidomastoid muscle

The sternocleidomastoid muscle is innervated by the accessory cranial nerve and branches of cervical spinal nerves C₂and C₃.

Which of the following is a role of the vitreous humor?

It supports the posterior surface of the lens.

The posterior segment of the eye is filled with a clear gel called the vitreous humor that binds tremendous amounts of water. Functions of vitreous humor include: transmitting light; supporting the posterior surface of the lens and holding the neural layer of the retina firmly against the pigmented layer; and contributing to intraocular pressure, helping to counteract the pulling force of the extrinsic eye muscles. The vitreous humor forms in the embryo and lasts for a lifetime.

Even though we have two eyes, why do we normally see only one image?

Information from each eye goes to both hemispheres for processing.

Notice that both eyes are set anteriorly and look in approximately the same direction. Their visual fields, each about 170 degrees, overlap to a considerable extent, and each eye sees a slightly different view. The visual cortex fuses the slightly different images delivered by the two eyes, providing us with a single image and depth perception (or three-dimensional vision), an accurate means of locating objects in space.

Which of the following is NOT a requirement for something to be tasted?

The tastant must contact the basal epithelial cells of the taste buds.

For a chemical to be tasted it must dissolve in saliva, diffuse into a taste pore, and contact the gustatory hairs. The tastant does not contact the basal epithelial cells - which act as stem cells, dividing and differentiating into new gustatory epithelial cells.

The final step in perceiving sound is __________.

the auditory cortex is stimulated

Stimulation of the primary auditory cortex, the end of the auditory pathway and final step in perceiving sound, provides conscious awareness of sound.

Which middle ear ossicle is attached to, and transmits vibratory motion to, the oval window?

stapes

The stapes is attached to the oval window, a thin membrane that separates the middle ear and the internal ear. The function of the ossicles is to transmit the vibratory motion of the eardrum to the oval window. In sequence, the tympanic membrane vibrations are transferred to the malleus, then the incus, and finally the stapes. As the stapes vibrates, it moves the oval window, which in turn sets the fluids of the internal ear into motion, eventually exciting the hearing receptors.

Which of the following is true of receptors for dynamic equilibrium?

The receptors for dynamic equilibrium respond to rotational forces.

The receptor for rotational (angular) movements of the head, called the crista ampullaris, or simply crista, is a minute elevation in the ampulla of each semicircular canal. Perception of these changes in head rotation is sometimes called our sense of dynamic equilibrium.

If retinal detachment occurs in the macula lutea, one can predict that there would be a significant loss of ______.

color vision

The macula lutea (yellow spot) is an area of the retina that is lateral to the blind spot. It is made up almost entirely of cones, specialized photoreceptor cells that help us see color.

Which of the following would be the LEAST likely to be associated with the development of motion sickness?

having a non-functional vestibular apparatus

The vestibular apparatus is important in detecting changes in linear velocity.

__________ are receptors that can respond to changes in pressure.

mechanoreceptors

Mechanoreceptors respond to mechanical force such as touch, pressure, vibration, and stretch.

Why might an individual experience the phenomenon known as "referred pain"?

Visceral pain afferents travel along the same pathways as somatic pain fibers.

The fact that visceral pain afferents travel along the same pathways as somatic pain fibers helps explain the phenomenon of referred pain, in which pain stimuli arising in one part of the body are perceived as coming from another part of the body. For example, a person experiencing a heart attack may feel pain that radiates along the medial aspect of the left arm.

Nerves that only carry impulses away from the central nervous system (CNS) are called __________.

motor nerves

Nerves that only carry impulses away from the CNS are motor (efferent) nerves.

__________ are collections of neuron cell bodies associated with nerves in the peripheral nervous system (PNS).

ganglia

Ganglia are collections of neuron cell bodies associated with nerve fibers in the PNS, whereas nuclei are collections of neuron cell bodies in the CNS.

Three main levels of neural integration operate in the somatosensory system. Which level involves processing in the sensory areas of the cerebral cortex?

perceptual level

Interpretation of sensory input (processing at the perceptual level) involves processing in cortical sensory areas. The ability to identify and appreciate sensations depends on the location of the target neurons in the somatosensory cortex.

Which of the following is not a main level of neural integration in the somatosensory system?

segmental

Which of the following is an incorrect statement regarding the occurrence of a sensation?

The stimulus energy must be converted into the energy of a graded potential
called a transduction potential.

In the somatosensory system there are no third-order neurons in the cerebellum.

T

Which of the receptor types contribute to the sense of touch by responding to deep pressure stimuli?

D

Deep pressure is detected by specific types of encapsulated receptors, such as the Pacinian corpuscles pictured in D.

Which of the receptor types above might function as a nociceptor?

A

Nociceptors respond to potentially damaging stimuli like noxious chemicals and extremes of temperature or pH. Nociceptors are generally associated with free nerve endings of specialized neurons.

Which of the receptor types pictured function as exteroceptors?

All

Exteroceptors are sensitive to stimuli arising outside the body.

Which of the receptor types pictured function exclusively as proprioceptors?

B

Proprioceptors are sensitive to stimuli associated with body movements. The muscle spindle shown in B fynctions only as proprioceptors.

Which of the following is NOT used to classify sensory receptors?

the number of dendritic endings present

The number of dendritic endings present is not a way of classifying sensory receptors.

Which of the following is composed of encapsulated nerve endings?

muscle spindles

Muscle spindles are classified as encapsulated nerve endings. In addition to nerve fibers, the connective tissue capsule also encloses a bundle of modified skeletal muscle fibers called intrafusal muscle fibers.

The first level of neural integration in the somatosensory system is the __________ level.

receptor

The receptor level is the first level of neural integration in the somatosensory system.

__________ do NOT exhibit the property of adaptation.

Tonic receptors

Tonic receptors provide a sustained response with little or no adaptation. Nociceptors and most proprioceptors are tonic receptors because of the protective importance of the information.

Which type of sensory receptor allows us to feel an insect landing on our skin?

mechanoreceptor

Mechanoreceptors respond to mechanical force such as pressure, vibration, stretch, and touch, allowing us to feel an insect landing on our skin.

Pressure, pain, and temperature receptors in the skin are ________.

exteroceptors

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

nociceptors

50. Which receptors adapt most slowly?

nociceptors

Feeling a gentle caress on your arm would likely involve all of the following except ________.

Pacinian corpuscles

Which of the following is not a way that sensory receptors are classified?

sensitivity to a stimulus

Pacinian corpuscles can be exteroceptors, interoceptors, or proprioceptor,

T

Identify the lettered muscle that is controlled by the abducens cranial nerve (CN VI).

B

What term means that the lens can change shape so that the eye can focus on items either close at hand or far away?

accommodation

Identify the lettered muscle responsible for depressing the eye and turning it laterally.

A

Identify the lateral rectus muscle. Select from letters A-D.

B

Identify the region that belongs to the fibrous layer of the eye. Select from choices A-D.

A

Identify the choroid layer. Select from letters A-D.

B

Identify the layer that contains both a single-celled pigmented layer and a neural layer. Select from choices A-D.

C

Identify the type of neuron that detects bright light and provides high resolution color vision. Select from choices A-D.

C

Identify the type of neuron found only in the fovea centralis. Select from choices A-D.

C

Identify the neuron that is last in the transmission pathway of light information given the cells shown in this image. Select from choices A-D.

A

The major function of the conjunctiva is to __________.

produce mucus to prevent the eyes from drying out

The major function of the conjunctiva is to produce a lubricating mucus that prevents the eyes from drying out.

Which of the following is NOTan accessory structure of the eye?

retina

The retina is a part of the eye (not an accessory structure). The accessory structures of the eye include the eyebrows, eyelids, conjunctiva, lacrimal apparatus, and extrinsic eye muscles.

The visible colored portion of the eye is the __________.

iris

The iris, the visible colored part of the eye, is the most anterior portion of the vascular layer (or middle coat) of the eye.

Which of the following is a characteristic of the lens?

The lens focuses light on the retina.

The lens is a biconvex, transparent, flexible structure that can change shape to precisely focus light on the retina. It is enclosed in a thin, elastic capsule and held in place just posterior to the iris by the ciliary zonule. Like the cornea, the lens is avascular; blood vessels interfere with transparency.

Choose the correctly paired terms.

nyctalopia: night blindness

Night blindness, or nyctalopia, is a condition in which rod function is seriously hampered, impairing one's ability to drive safely at night.

A stroke that affects the left visual cortex would lead to __________.

blindness in the right half of the visual field

If neural destruction occurs beyond the optic chiasma - in an optic tract, the thalamus, or visual cortex - then part or all of the opposite half of the visual field will be lost. Thus, a stroke affecting the left visual cortex leads to blindness in the right half of the visual field.

The receptors for smell are activated when __________.

dissolved odorants bind to receptor proteins in the cilium membranes

Dissolved odorants stimulate olfactory sensory neurons by binding to receptor proteins in the olfactory cilium membranes. This triggers the opening of cation channels, which results in generation of a receptor potential. Ultimately (assuming threshold stimulation) an action potential is conducted to the first relay station in the olfactory bulb.

If a chalazion interferes with glandular secretion, the immediate outcome would be ______.

friction on the anterior surface of the eye

The lacrimal glands produce a saline solution, which washes and lubricates the eyeball. It secretes its products via glandular secretion.

Which of the following statements is FALSE?

Nyctalopia affects vision in the fovea centralis, resulting in impaired vision.

Nyctalopia (night blindness) occurs due to the loss of normal rod function.

If the optic chiasma is destroyed but the rest of the visual pathway to the brain is not damaged, the result would be ______.

loss of peripheral vision on both the far right and far left sides of the visual field

At the optic chiasm, the nerves from the medial aspect of each optic nerve (retina) cross to the opposite side. The lens system reverses all images so the medial half of each retina receives light rays from the most lateral part of the visual field and the lateral retina receives images from the most medial visual field.

Conjunctivitis does not directly affect ______.

the conjunctival sac

The conjunctival sac is the space between the eyelids and the eyeball that is lined by the conjunctiva.

When a person's cold is accompanied by "watery eyes," there is reduced flow of lacrimal fluid directly into the ______.

lacrimal puncta

This structure is the beginning point of each lacrimal canaliculi. They are seen on the medial portion of each eyelid. They function to collect tears produced by the lacrimal glands. These openings can become swollen or blocked during a cold or allergic reaction.

Which of the following nerves would you predict is NEVER involved in the development of strabismus?

trigeminal (V)

Strabismus is a condition in which the eyes lack normal alignment, usually due to a lack of control of the extraocular muscles. This nerve functions as the major sensory nerve of the face but also controls the blink reflex.

In glaucoma, damage occurs primarily to the ______.

ganglion cells in the retina

Glaucoma is an eye disorder where the optic nerve suffers damage that can progress to blindness if left untreated. Damage occurs because of an increase in intraocular pressure. The ganglion cells of the retina help to form the optic nerve, which exits the back of the eyeball at the optic disc.

In theory, cataracts could be prevented by invention of a treatment that would ______.

increase diffusion rates within the lenses

A cataract is a clouding over of the eye lens that prevents normal entry of light. It is caused by a lack of nutrient delivery to the deep lens fibers, which leads to aggregation of crystallin proteins. Nutrients travel to this area of the eye via diffusion from blood vessels.

Which of the following statements is true?

Contraction of the ciliary muscles is required for hyperopic individuals to clearly see distant objects.

Persons who are farsighted (hyperopia) can see distant objects because their cillary muscles are in a state of continuous contraction that moves the object forward to focus it on the retina.

In a 30 year old man who has red-green color blindness, light having a wavelength of 530 nm is perceived as being green. This man ______.

perceives that red light has a green color

Green cones normally respond to light around wavelengths 530 nm but red cones respond to light at 560 nm. In people with red-green color blindness, red and green are seen as the same color. They may have a deficit or complete lack of red or green cones.

Which accessory eye structures function to produce the tears that cleanse and protect the eye?

lacrimal glands

The lacrimal gland lies in the orbit above the lateral end of the eye. It continually releases a dilute saline solution called lacrimal secretion, or tears, into the superior part of the conjunctival sac through several small excretory ducts. Lacrimal fluid contains mucus, antibodies, and lysozyme, an enzyme that destroys bacteria. Thus, it cleanses and protects the eye surface as it moistens and lubricates it.

Which structure in the eye provides nutrition to all eye layers?

choroid

The vascular layer forms the middle coat of the eyeball. Also called the uvea, this pigmented layer has three regions: choroid, ciliary body, and iris. The choroid is a blood vessel-rich, dark brown membrane that forms the posterior five-sixths of the uvea. Its blood vessels nourish all eye layers. Its brown pigment, produced by melanocytes, helps absorb light, preventing it from scattering and reflecting within the eye.

What part of the eye constitutes the blind spot?

optic disc

The optic disc, where the optic nerve exits the eye, is a weak spot in the posterior wall of the eye because it is not reinforced by the sclera. The optic disc is also called the blind spot because it lacks photoreceptors, so light focused on it cannot be seen. Nonetheless, we do not usually notice these gaps in our vision because the brain uses a sophisticated process called filling in to deal with absence of input.

Which photoreceptors respond to very dim light?

rods

Rods are our dim-light and peripheral vision receptors. They are more numerous and far more sensitive to light than cones are, but they do not provide sharp images or color vision. This is why colors disappear and the edges of objects appear fuzzy in dim light and at the edges of our visual field.

Roger went for his yearly eye examination and was informed that his intraocular pressure was slightly elevated (at 22 mm Hg). The physician expressed concern over this condition and noted that if the condition got worse, eyedrops would be merited. What is wrong with Roger's eyes? What are the possible consequences of this condition? What is the function of the eyedrops?

The condition is glaucoma. Blindness could result if not treated or caught early. The eyedrops increase the rate of aqueous humor drainage or decrease its production.

Baby Susie's pediatrician notices that one of her eyes rotates outward and that she does not appear to be using it for vision. What is her condition, and what does the pediatrician recommend?

Susie has strabismus. The doctor's recommendations are for eye exercises and/or placing a patch over the unaffected eye; in severe cases, the condition may require surgery.

Ling, a 75-year-old grandmother, complained that her vision was becoming obscured. Upon examination by an ophthalmologist she was told she had cataracts. What are cataracts, how do they occur, and how are they treated?

A cataract is a clouding of the lens. Some cataracts are congenital, but most are due to age-related hardening and thickening of the lens, diabetes mellitus, or exposure to UV rays over time. The lens can be removed and replaced with an artificial lens.

What is the main function of the rods in the eye?

vision in dim light

Nerve fibers from the medial aspect of each eye ________.

cross over to the opposite side at the chiasma

Ordinarily, it is not possible to transplant tissues from one person to another, yet corneas can be transplanted without tissue rejection. This is because the cornea ________.

has no blood supply

There are three layers of neurons in the retina. The axons of which of these neuron layers form the optic nerves?

ganglion cells

The first "way station" in the visual pathway from the eye, after there has been partial crossover of the fibers in the optic chiasma, is the ________.

lateral geniculate body of the thalamus

What structure regulates the amount of light passing to the visual receptors of the eye?

iris

Farsightedness is more properly called ________.

hyperopia

100. Seventy percent of all sensory receptors are located in the ________.

eye

The mucous membrane that lines the eyelids and is reflected over the anterior surface of the eyeball is the conjunctiva.

T

The bending of light rays is called reflection.

F

Vitamin D needed by the photoreceptor cells is stored by the cells of the retina pigmented layer.

F

The photoreceptor cells are sensitive to damage from light.

T

The optic disc is the location where the optic nerve leaves the eyeball.

T

The extrinsic eye muscle motor units contain only 8 to 12 muscle cells and in some cases as few as 2 or 3 muscle cells.

T

Ciliary muscles are a type of skeletal muscle.

F

What condition results when distant objects focus in front of the retina, rather than on it?

myopia

This image best illustrates an eyeball that is __________.

emmetropic

The boundary between the external and middle ear is the __________.

tympanic membrane

The tympanic membrane, or eardrum, forms the boundary between the outer and middle ears. Sound waves make the eardrum vibrate. The eardrum, in turn, transfers the sound energy to the tiny bones of the middle ear and sets them vibrating.

Ringing in the ears is called __________.

tinnitus

Tinnitus is a ringing or clicking sound in the ears in the absence of auditory stimuli. It is usually a symptom rather than a disease. For example, tinnitus is one of the first symptoms of cochlear nerve degeneration. It may also signal inflammation of the middle or internal ears and is a side effect of some medications, such as aspirin.

Vision is fully developed at birth.

F

Most taste buds are located __________.

on the tongue

Most of our 10,000 or so taste buds - the sensory organs for taste - are located on the tongue. A few taste buds are scattered on the soft palate, inner surface of the cheeks, pharynx, and epiglottis of the larynx, but most are found in papillae, peglike projections of the tongue mucosa that make the tongue surface slightly abrasive.

Which of the following is the basic taste quality responsible for the "beef taste" of steak?

umami

Umami ("delicious"), a subtle taste discovered by the Japanese, is elicited by the amino acids glutamate and aspartate, which appear to be responsible for the "beef taste" of steak, the characteristic tang of aging cheese, and the flavor of the food additive monosodium glutamate.

Which of the following is true about gustatory receptors?

Complete adaptation occurs in about one to five minutes.

Taste buds are not found ________.

in filiform papillae

Receptors for hearing are located in the ________.

cochlea

Which of the follow types of neurons are replaced throughout adult life?

olfactory receptor cells

Bitter taste is elicited by ________.

alkaloids

Sour taste receptors are stimulated by hydrogen ions of acidic food substances.

T

Identify the structure that forms cranial nerve I. Select from choices A-D.

C

Which cells in this pathway are ciliated? Select from choices A-D.

D

Identify the cells embedded in the nasal epithelium. Select from choices A-D.

D

Which of these lettered structures serves as the taste cells?

C

Which of the lettered structures houses receptors for sweet, sour, salty, and bitter tastes?

C

Which of these lettered structures acts as a stem cell to regenerate the taste cells?

B

Where are equilibrium receptors located?

in the semicircular canals and in the vestibule of the ear

The equilibrium receptors in the semicircular canals and vestibule are collectively called the vestibular apparatus. The receptors in the vestibule monitor linear acceleration and the position of the head with respect to gravity. Because gravity is constant, this is sometimes called our sense of static equilibrium. The semicircular canals monitor changes in head rotation, sometimes called our sense of dynamic equilibrium.

There are __________ auditory ossicles in the ear.

three

The tympanic cavity is spanned by the three smallest bones in the body: the auditory ossicles. These bones, named for their shape, are the malleus ("hammer"), the incus ("anvil"), and the stapes ("stirrup"). The "handle" of the malleus is secured to the eardrum, and the base of the stapes fits into the oval window.

The receptor organ for hearing is the __________.

spiral organ (of Corti)

The cochlear duct (of the cochlea) houses the receptor organ of hearing, called the spiral organ or the organ of Corti. It responds to fluid movement (vibration) in the cochlea generated by the tympanic membrane and transmitted by the middle ear ossicles.

The distance between two consecutive wave crests is the __________.

wavelength

The distance between two consecutive crests (or troughs) is the wavelength of the sound and is constant for a particular tone. The shorter the wavelength, the higher the frequency of the sound.

Information from balance (equilibrium) receptors goes directly to __________.

the brain stem

Our responses to body imbalance, such as when we stumble, must be fast and reflexive. By the time we "thought about" correcting our fall, we would already be on the ground! Accordingly, information from equilibrium receptors goes directly to reflex centers in the brain stem, rather than to the cerebral cortex as with the other special senses.

Choose the FALSE statement about the olfactory epithelium.

It is made of simple squamous epithelium.

The olfactory epithelium is made of pseudostratified (not simple squamos) epithelium.

Eye color is determined by the amount of brown pigment present in the iris.

T

Although irises come in different colors (iris = rainbow), they contain only brown pigment. When they have a lot of pigment, the eyes appear brown or black. If the amount of pigment is small and restricted to the posterior surface of the iris, the unpigmented parts simply scatter the shorter wavelengths of light and the eyes appear blue, green, or gray. Most newborn babies' eyes are slate gray or blue because their iris pigment is not yet developed.

During otitis media, large amounts of fluid or pus may accumulate in the tympanic cavity; the fluid is primarily ______.

interstitial fluid

Interstitial fluid is the fluid between cells. Pus is a thin, protein-rich fluid that consists of tissue fluid, dead cells, and immune cells found at a sight of inflammation.

Which of the following correctly matches the equilibrium receptor to the type of equilibrium it monitors?

maculae/static equilibrium

The maculae ("spots"), one in each saccule wall and one in each utricle wall, are sensory receptor organs that monitor the position of the head in space (with respect to gravity). Because gravity is constant, this is sometimes called our sense of static equilibrium.

Which of the following is the receptor organ for hearing?

spiral organ (of Corti)

The cochlear duct (of the cochlea) houses the receptor organ of hearing, called the spiral organ or the organ of Corti. It responds to fluid movement (vibration) in the cochlea generated by the tympanic membrane and transmitted by the middle ear ossicles.

What is the vestibular apparatus?

the equilibrium receptors in the semicircular canals and vestibule

The equilibrium receptors in the semicircular canals and vestibule are collectively called the vestibular apparatus. The receptors in the vestibule monitor linear acceleration and the position of the head with respect to gravity. The semicircular canals monitor changes in head rotation.

Olfactory epithelium

Chemically sensitive cilia are found in this structure.

Crista ampullaris

Hair cells receptive to changes in dynamic equilibrium are found in this structure.

Taste buds

Chemically sensitive microvilli found in this structure.

MaculaHair cells receptive to changes in static equilibrium are found in this structure.

Hair cells receptive to changes in static equilibrium are found in this structure.

The oval window is connected directly to which passageway?

scala vestibuli

As sound levels increase in the spiral organ (of Corti), ________.

outer hair cells stiffen the basilar membrane

The receptor for static equilibrium is the ________.

macula

Which of the following structures is not part of the external ear?

pharyngotympanic tube

There are __________ pairs of cranial nerves.

12

The majority of the cranial nerves attach to the __________.

brain stem.

Yes, 10 of the 12 pairs of cranial nerves attach to the brainstem.

Spinal nerves are all classified as __________.

mixed nerves

All 31 pairs of spinal nerves are mixed nerves; they carry both afferent (sensory) impulses toward the CNS and efferent (motor) impulses away from the CNS.

Choose the FALSE statement about nerves.

The majority of a nerve's bulk is due to axons.

Actually, axons constitute only a small fraction of a nerve's bulk. The balance consists chiefly of myelin, the protective connective tissue wrappings, blood vessels, and lymphatic vessels.

The hyperalgesia that is common in phantom limb pain could be blocked if a new drug was developed that could prevent (without triggering any side-effects) the ______.

diffusion of calcium ions through NMDA receptors

Diffusion of calcium ions through these receptors cause a depolarizing event and activate and action potential in the neuron.

Which connective tissue layer directly surrounds each axon in a nerve?

endoneurium

Within a nerve, each axon is surrounded by endoneurium, a delicate layer of loose connective tissue that also encloses the fiber's associated Schwann cells.

Nerves that carry impulses toward the CNS only are ________.

afferent nerves

After axonal injury, regeneration in peripheral nerves is guided by ________.

Schwann cells

Select the statement that is most correct.

Ganglia associated with afferent nerve fibers contain cell bodies of sensory neurons.

The structure that allows equalization of the pressure in the middle ear with that outside the body is the external auditory meatus.

F

Static equilibrium involves linear acceleration as well as changes in head rotation.

F

The fluid contained within the membranous labyrinth is called perilymph.

F

The phrenic nerve serves the __________.

diaphragm

The phrenic nerve, which arises from the cervical plexus, supplies both motor and sensory fibers to the diaphragm, the main breathing muscle. Irritation of the phrenic nerve causes spasms of the diaphragm, or hiccups. If both phrenic nerves are severed, the diaphragm is paralyzed and respiratory arrest occurs.

In carpal tunnel syndrome, the __________ is compressed.

median nerve

The median nerve descends through the arm and forearm before passing through the wrist. Compression of this nerve in the anterior wrist causes carpal tunnel syndrome.

Which cranial nerve transmits information about our sense of equilibrium?

vestibulocochlear

The vestibular branch of the vestibulocochlear nerve transmits afferent impulses for the sense of equilibrium. The cochlear branch transmits afferent impulses for the sense of hearing.

Which of the following cranial nerves carries only sensory information?

olfactory

A purely sensory nerve, the olfactory nerve carries afferent impulses for the sense of smell.

David, an aspiring baseball player, was struck on the left side of his face with a fastball pitch. He was not wearing a safety helmet. His zygomatic arch was crushed, as well as parts of the temporal bone. Following the accident and reconstructive surgery, he noted that his left lower eyelid was still drooping and the corner of his mouth sagged. What nerve damage did he sustain?

Facial nerve damage on his left side

A nurse is asked about the cause of the excruciating pain of tic douloureux. How should the nurse answer?

The excruciating pain is caused by inflammation of the trigeminal nerve. Pressure on the trigeminal nerve root can turn normal stimuli, like tooth brushing, into painful stimuli.

The ________ nerve is not a branch of the trigeminal nerve.

cervical

Problems in balance may follow trauma to which nerve?

vestibulocochlear

A fracture of the ethmoid bone could result in damage to which cranial nerve?

olfactory

A patient who received a blow to the side of the skull exhibits the following signs and symptoms on that side of the face: he is unable to close his eye, and the corner of his mouth droops. Which cranial nerve has been damaged?

facial

The cranial nerve with a cervical origin (spinal cord) is the ________.

accessory

The glossopharyngeal nerve is the only cranial nerve that contains sensory fibers.

F

The second cranial nerve forms a chiasma at the base of the brain for partial crossover of neural fibers.

T

The only cranial nerves to extend beyond the head and neck region are the vagus nerves.

T

The thickest and longest nerve in the body is the __________.

sciatic nerve

The largest branch of the sacral plexus, the sciatic nerve is the thickest and longest nerve in the body.

Which of the following lists the hierarchy of motor control from lowest to highest level of control?

segmental level, projection level, precommand level

The hierarchy of motor control from lowest to highest level of control is: segmental level, projection level, and precommand level.

Which structure is involved in the segmental level of motor control?

spinal cord

The lowest level of the motor hierarchy, the segmental level, consists of reflexes and spinal cord circuits that control automatic movements.

Somatic reflexes activate __________.

skeletal muscle

The knee-jerk reflex is an example of a __________.

stretch reflex

The most familiar clinical example of a stretch reflex is the knee-jerk reflex. The overall goal of a stretch reflex is to maintain a muscle's length, and in turn maintain body position. For example, the knee-jerk reflex, during which the knee extensors contract in response to being stretched, helps keep your knees from buckling when you are standing upright.

Hiccups could occur if there was irritation or damage to the ______.

motor branches of ventral rami associated with the C₃-C₅ region of the spinal cord

The ventral rami of spinal nerves contain motor fibers that originate from neuron soma found in the spinal cord. These efferent pathways activate the contraction of skeletal muscle. The phrenic nerve branches from this region and innervates the skeletal muscle of the diaphragm.

The brachial plexus can be palpated at the lower lateral border of the sternocleidomastoid muscle. Injury to the brachial plexus could cause weakness or paralysis to all of the following EXCEPT the ______.

sternocleidomastoid muscle

The sternocleidomastoid muscle is innervated by the accessory cranial nerve and branches of cervical spinal nerves C₂ and C₃.

In carpal tunnel syndrome, there may be tingling and numbness in the thumb due to compression of the ______.

cutaneous branches of the median nerve

The median nerve cutaneous branch carries sensory input from the skin of the lateral 2/3rds of the hand, palm side and dorsum of fingers 2-3.

Damage to the ulnar nerve could result in the inability to ______.

flex the wrist

One action of the flexor carpi ulnaris muscle is wrist flexion. This muscle is innervated by the ulnar nerve.

If "wrist drop" were to appear, there would also be an increased probability of ______.

inability to extend the forearm

Wrist drop occurs due to paralysis of the radial nerve. This nerve provides innervations to the triceps brachii muscle, which is the prime mover of forearm extension.

A herniated lumbar disc could interfere with ______.

skin sensations from the lateral thigh

skin sensations from the medial thigh

adduction of the thigh

The branches of lumbar plexus include the following nerves: femoral, obturator, lateral femoral cutaneous, iliohypogastric, ilioinguinal, and genitofemoral.

Sciatica has no direct affect on ______.

control of the adductor longus

This muscle is innervated by the obturator nerve, which is a branch of the lumbar plexus.

What type of nerve fibers are found in the ventral ramus of a spinal nerve?

both sensory and motor

The ventral (motor) nerve roots and the dorsal (sensory) nerve roots merge as they leave the vertebral column to form the spinal nerve proper, a mixed nerve. The spinal nerve immediately branches into a small dorsal ramus (branch) and a larger ventral ramus, both of which are mixed nerves (meaning they contain both motor and sensory fibers).

The primary nerve that controls breathing is found in which nerve plexus?

cervical

The phrenic nerve arises from the cervical plexus. It supplies both motor and sensory fibers to the diaphragm, the main breathing muscle.

200. Ralph sustained a leg injury in a bowling accident and had to use crutches. Unfortunately, he never took the time to learn how to use them properly. After two weeks of use, he noticed his fingers were becoming numb. Then he noticed his arms were getting weaker and had a tingling sensation. What could be his problem?

Compression of the radial nerve (in the region of the armpit) may cause temporary cessation of nervous transmission, often called "Saturday night paralysis."

A major nerve of the lumbar plexus is the ________.

femoral

A fall or an improperly delivered gluteal injection could result in ________.

sciatica

The posterior side of the thigh, leg, and foot is served by the ________ nerve.

tibial

Starting at the spinal cord, the subdivisions of the brachial plexus are (in order):

roots, trunks, divisions, and cords

The meningeal branch of a spinal nerve actually reenters the vertebral canal to innervate the meninges and blood vessels.

T

Dorsal and ventral rami are similar in that they both contain sensory and motor fibers.

T

Irritation of the phrenic nerve may cause diaphragm spasms called hiccups.

T

The obturator nerve branches from the sacral plexus.

F

The musculocutaneous nerve is a major nerve of the brachial plexus.

T

The dorsal ramus consists only of motor fibers bringing information to the spinal cord.

F

Dermatomes are skin segments that relate to sensory innervation regions of the spinal nerves.

T

Select the true statements (more than one) about the characteristics of sensory neurons in the stretch reflex?

When a stretch activates the muscle spindle, these sensory neurons transmit impulses at a higher frequency.

These sensory neurons transmit afferent impulses toward the spinal cord (CNS).

Which is the true statement about the synapses in the spinal cord in the stretch reflex?

Multipolar interneurons make inhibitory polysynaptic synapses to the antagonist muscle.

Inhibitory signals to the muscle antagonistic to the stretched muscle will not counteract the stretching, reciprocal inhibition.

Examine the cross section through the lumbar section of the spinal cord and the two patellar reflex pathways shown. What identifies these synapses?

Afferent impulses synapse with motor neurons and interneurons.

Pathways will activate one muscle and simultaneously inhibit its antagonist muscle.

Examine and characterize the two motor pathways in the stretch patellar reflex.

Alpha motor neurons send efferent messages to the quadriceps, while parallel efferent messages to the hamstrings are reduced.

A patient sustains a ventral horn injury to the lumbar region of the spine. This injury has damaged the cell bodies of several afferent nerves within the region. Predict how the patient's patellar reflex might be affected.

The patient's patellar reflex would be absent or weak.

Which of the following does NOT occur as people age?

Peripheral nerves die off.

Actually, peripheral nerves remain viable and normally functional throughout life unless subjected to traumatic injury or ischemia.

The peripheral nervous system (PNS) includes the brain and spinal cord.

F

Actually, the PNS includes all neural structures outside of the brain and spinal cord.

What parts of the brain ultimately plan and coordinate complex motor activities?

cerebellum and basal nuclei

The cerebellum and basal nuclei are the ultimate planners and coordinators of complex motor activities and are therefore at the top of the motor control hierarchy.

In the figure below, which letter points to an afferent neuron?

A

What is the specific function of the structure labeled E?

determination of muscle length

The muscle spindle indicated by E is functions as a proprioceptor that is responsive to changes in the length of the surrounding muscle.

The synapse between which of the following two neurons is a part of a monosynaptic reflex arc?

A,B

A monosynaptic reflex arc includes a synapse between sensory and motor neurons without the involvement of an interneuron.

The nerve fibers labeled B and C are both classified as which of the following?

alpha efferent fibers

Alpha efferent fibers control the main effector cells of the muscle, the extrafusal muscle fibers.

Which of the following muscles might be represented by that labeled F in the figure during the patellar (knee jerk) reflex?

rectus femoris

The rectus femoris is one of the quadriceps. Stimulation of muscle spindles by tapping of the patellar ligament results in the reflex contraction of these muscles and the extension of the knee.

Anatomically, all general sensory receptors are encapsulated nerve endings.

F

Anatomically, general sensory receptors are nerve endings that are either nonencapsulated (free) or encapsulated.

Increased nerve impulse activity in the neuron labeled A will generally result in ______.

the relaxation of the muscle labeled G

Increased muscle length is conveyed to the CNS via neuron A. Efferent motor pathways lead to the contraction of the stretched muscle (F) and the relaxation of the antagonistic muscle (G).

CNS nerve fibers lack the intrinsic capacity to regenerate, while PNS nerve fibers are able to regenerate.

T

Unlike peripheral nerve fibers, most CNS fibers never regenerate. Consequently, damage to the brain or spinal cord has been viewed as irreversible.

A knee-jerk reflex that is unusually strong may be caused by ______.

transmission of excitatory signals from the brain to the neurons that form the femoral nerve

The femoral nerve innervates all of the muscles that act to extend the knee (quadriceps).

Which reflex is important for maintaining muscle tone?

stretch reflex

The stretch reflex is important for maintaining muscle tone (and thus muscle length) and adjusting it reflexively. It is most important in the large extensor muscles that sustain upright posture and in postural muscles of the trunk.

Which reflex is triggered when a stranger suddenly grasps your arm?

crossed-extensor reflex

The grasped arm is withdrawn (via the flexor reflex) as the opposite arm pushes you away from the attacker (via crossed-extensor reflex). As in this scenario, the crossed-extensor reflex often accompanies the flexor reflex.

Stretch

Prevents muscle overstretching and maintains muscle tone.

Flexor

Produces a rapid withdrawal of the body part from a painful stimulus; ipsilateral.

Crossed-extensor

Consists of an ipsilateral withdrawal reflex and a contralateral extensor reflex; important in maintaining balance.

Plantar

Tests both upper and lower motor pathways. The sole of the foot is stimulated with a dull instrument.

Tendon

Produces muscle relaxation and lengthening in response to tension; the contracting muscle relaxes as its antagonist is activated.

The patellar "knee jerk" reflex is an example of a(n) ________.

stretch reflex

A reflex that causes muscle relaxation and lengthening in response to muscle tension is called a ________.

Golgi tendon reflex

Reciprocal inhibition means that while one sensory nerve is stimulated, another sensory neuron for synergistic muscles in the same area is inhibited and cannot respond.

F