Chapter 15: Structure and function of the Neurologic System

Controls motor functions to the pharynx and salivary glands and sensory functions from the pharynx and tongue.

Glossopharyngeal nerve The glossopharyngeal nerve affects control over the motor fibers that serve the pharynx (throat) and salivary glands, as well as the sensory fibers that carry impulses from the pharynx, posterior tongue (taste buds), and pressure receptors of the carotid artery.

Affects control over the motor fibers to the muscles of tongue and sensory impulses from the tongue to the brain.

Hypoglossal nerve The hypoglossal nerve affects control over the motor fibers to the muscles of tongue and sensory impulses from the tongue to the brain.

Is purely sensory and carries impulses for the sense of smell

Olfactory nerve The olfactory nerve is purely sensory and carries impulses for the sense of smell.

Carries sensory and motor fibers to the pharynx and larynx.

Spinal accessory nerve

Provides motor and sensory functions to the face, mouth, nose, and eyes.

Trigeminal nerve The trigeminal nerve affects control over both the motor and sensory functions to the face; conducts sensory impulses from the mouth, nose, surface of eye, and dura mater; it also contains

Fibers emerge from the posterior midbrain and exit from the skull to run to the eye.

Trochlear nerve The trochlear nerve fibers emerge from posterior midbrain and exit from skull to affect control over the proprioceptor and motor fibers for the superior oblique muscle of eye (extraocular muscle).

Is made up of parasympathetic motor fibers that supply the smooth muscles of the abdominal organs.

Vagus nerve The vagus nerve affects control over the fibers that carry sensory and motor impulses for the pharynx. A large part of this nerve is parasympathetic motor fibers that supply smooth muscles of the abdominal organs and is capable of receiving sensory impulses from the viscera.

Transmits impulses for the sense of hearing.

Vestibulocochlear nerve The vestibulocochlear nerve is purely sensory; the vestibular branch transmits impulses for the sense of equilibrium; the cochlear branch transmits impulses for the sense of hearing.

Which pathway carries sensory information toward the central nervous system (CNS)? a. Ascending c. Somatic b. Descending d. Efferent

ANS: A Peripheral nerve pathways can be afferent (ascending) pathways that carry sensory impulses toward the CNS. The remaining options do not carry sensory information to the CNS.

Both oligodendroglia and Schwann cells share the ability to: a. Form a myelin sheath b. Remove cellular debris c. Transport nutrients d. Line the ventricles

ANS: A The function of oligodendroglia (oligodendrocytes) is to deposit myelin within the central nervous system (CNS). Oligodendroglia are the CNS counterpart of Schwann cells. The remaining options are not reflective of the common function of these structures.

The membrane that separates the brain's cerebellum from its cerebrum is the: a. Tentorium cerebelli b. Falx cerebri c. Arachnoid membrane d. Falx cerebelli

ANS: A The tentorium cerebelli is a membrane that separates the cerebellum below from the cerebral structures above. The remaining options do not perform the function described in the stem.

The region responsible for the motor aspects of speech is located in the: a. Wernicke area in the temporal lobe b. Broca area in the frontal lobe c. Wronka area in the parietal lobe d. Barlow area in the occipital lobe

ANS: B Broca speech area is the only region responsible for the motor aspects of speech.

Which type of axon transmits a nerve impulse at the highest rate? a. Large nonmyelinated b. Large myelinated c. Small nonmyelinated d. Small myelinated

ANS: B If the myelin layer is tightly wrapped many times around the axon and is forming the nodes of Ranvier, then conduction velocity increases and the neuron is referred to as myelinated. The increased diameter of the myelinated axons allows for the transmission of impulses at a faster rate. The other options do not affect nervous impulse transmission rates.

What is an effect of the sympathetic nervous system? a. Stimulation of peristalsis b. Increased blood sugar levels c. Reduction in heart rate d. Pupillary constriction

ANS: B In general, sympathetic stimulation promotes responses that are concerned with the protection of the individual, which include increased blood sugar levels, temperature, and blood pressure. The responses noted in the remaining options are not a result of sympathetic stimulation.

During a synapse, what change occurs after the neurotransmitter binds to the receptor? a. The permeability of the presynaptic neuron changes; consequently, its membrane potential is changed as well. b. The permeability of the postsynaptic neuron changes; consequently, its membrane potential is changed as well. c. The postsynaptic cell prevents any change in permeability and destroys the action potential. d. The presynaptic cell synthesizes and secretes additional neurotransmitters.

ANS: B The binding of the neurotransmitter at the receptor site changes the permeability of the postsynaptic neuron and, consequently, its membrane potential. The remaining options do not accurately describe the occurrence.

Which area of the brain assumes the responsibility for conscious and unconscious muscle synergy and for maintaining balance and posture? a. Cerebrum b. Cerebellum c. Diencephalon d. Brainstem

ANS: B The cerebellum is responsible for conscious and unconscious muscle synergy and for maintaining balance and posture. This role is not assumed by any of the remaining options.

Where is the cerebrospinal fluid produced? a. Arachnoid villi b. Choroid plexuses c. Ependymal cells d. Pia mater

ANS: B The choroid plexuses are the structures that produce CSF; they arise from the pia mater. The remaining options do not have a role in CSF production.

From which part of the midbrain do cranial nerves V to VIII emerge? a. Midbrain b. Pons c. Medulla oblongata d. Lateral colliculi

ANS: B The nuclei of cranial nerves V through VIII (see Table 15-6 for discussion) are located only in the pons

What name is given to a large network of neurons within the brainstem that is essential for maintaining wakefulness? a. Midbrain b. Reticular activating system c. Medulla oblongata d. Pons

ANS: B The reticular activating system is essential for maintaining wakefulness. The remaining options are not essential to this function.

The ability of the eyes to track moving objects through a visual field is primarily a function of which colliculi? a. Inferior b. Superior c. Mid d. Posterior

ANS: B The superior colliculi are involved with voluntary and involuntary visual motor movements (e.g., the ability of the eyes to track moving objects in the visual field). Tracking moving objects is not the primary function of the remaining options.

Which statement is true regarding upper motor neurons? a. Upper motor neurons directly influence muscles. b. They modify spinal reflex arcs. c. Upper motor neurons are located in the gray matter of the spinal cord. d. They extend their dendritic processes out of the CNS.

ANS: B Upper motor neurons (i.e., corticospinal tract) are the classification of motor pathways completely contained within the CNS. Their primary roles include directing, influencing, and modifying reflex arcs, lower-level control centers, and motor and some sensory neurons. The remaining options do not accurately describe the characteristic functions of upper motor neurons.

The nurse recognizes that a patient's diagnosis of a viral infection of the brain's meningeal layer is supported by which diagnostic laboratory result? a. Chloride <110 mEq/L b. Leukocytes >10/mm3 c. Protein <10 mg/dl d. Glucose <40 mg/dl

ANS: B Viral infections causing meningitis will produce a white blood cell (leukocyte) count greater than 10/mm 3. The chloride level is observed in tuberculous meningitis, the protein level has little clinical significance, and the glucose level is observed in patients with acute bacterial meningitis.

What parts of the brain mediate the expression of affect, both emotional and behavioral states? a. Hypothalamus and subthalamus b. Parietal and frontal lobes c. Limbic system and prefrontal cortex d. Basal ganglia and medulla oblongata

ANS: C Extensive connections with the limbic system and prefrontal cortex mediate the expression of affect, both emotional and behavioral states. The remaining options are not involved in these expressions.

The neurotransmitter, norepinephrine, is secreted in the: a. Somatic nervous system b. Parasympathetic preganglion c. Sympathetic postganglion d. Parasympathetic postganglion

ANS: C Most postganglionic sympathetic fibers release norepinephrine (adrenaline). The remaining options do not reflect the correct site of norepinephrine secretion.

Which nerves are capable of regeneration? a. Nerves within the brain and spinal cord b. Peripheral nerves that are cut or severed c. Myelinated nerves in the peripheral nervous system d. Unmyelinated nerves of the peripheral nervous system

ANS: C Nerve regeneration is limited to only myelinated fibers and generally occurs only in the peripheral nervous system.

The collateral blood flow to the brain is provided by the: a. Carotid arteries b. Basal artery c. Circle of Willis d. Vertebral arteries

ANS: C The arterial circle (circle of Willis) (see Figure 15-20) is a structure credited with the ability to compensate for reduced blood flow from any one of the major contributors (collateral blood flow). The remaining options are not considered sources of collateral blood flow.

The brain receives approximately what percentage of the cardiac output? a. 80% b. 40% c. 20% d. 10%

ANS: C The brain receives approximately 20% of the cardiac output, or 800 to 1000 ml of blood flow per minute.

Which of the meninges closely adheres to the surface of the brain and spinal cord and follows the sulci and fissures? a. Dura mater b. Arachnoid c. Pia mater d. Inner dura

ANS: C The delicate pia mater closely adheres to the surface of the brain and spinal cord and even follows the sulci and fissures. The remaining options are not represented in the description provided in the stem.

From which part of the midbrain do cranial nerves IX to XII emerge? a. Midbrain b. Pons c. Medulla oblongata d. Lateral colliculi

ANS: C The nuclei of cranial nerves IX through XII (see Table 15-6 for discussion) are located only in the medulla oblongata.

Thought and goal-oriented behaviors are functions of which area of the brain? a. Cerebellum b. Limbic system c. Prefrontal lobe d. Occipital lobe

ANS: C The prefrontal area is responsible for goal-oriented behavior (i.e., ability to concentrate), short-term or recall memory, and the elaboration of thought and inhibition on the limbic (emotional) areas of the CNS. The remaining options are not involved in these functions.

Norepinephrine produces what primary response? a. Increased contractility of the heart b. Release of renin from the kidney c. Vasoconstriction d. Pupillary dilation

ANS: C The primary response from norepinephrine is the stimulation of the α1-adrenergic receptors that cause vasoconstriction. The remaining options do not accurately reflect the primary response of norepinephrine.

The function of arachnoid villi is to: a. Produce cerebrospinal fluid b. Provide nutrients to the choroid plexuses c. Transmit impulses within the meninges d. Absorb cerebrospinal fluid into the cerebral venous sinuses

ANS: D CSF is reabsorbed by means of a pressure gradient between the arachnoid villi and the cerebral venous sinuses. The remaining options do not accurately describe the function of arachnoid villi.

Maintenance of a constant internal environment and the implementation of behavioral patterns are main functions of which area of the brain? a. Thalamus b. Epithalamus c. Subthalamus d. Hypothalamus

ANS: D Hypothalamic function falls into two major areas: (1) maintenance of a constant internal environment, and (2) implementation of behavioral patterns. The remaining options do not address these functions.

Parkinson and Huntington diseases are associated with defects in which area of the brain? a. Thalamus b. Medulla oblongata c. Cerebellum d. Basal ganglia

ANS: D Parkinson and Huntington diseases are conditions associated with defects of the basal ganglia. No current research supports the role of any of the other options in these diseases.

Reflex activities concerned with heart rate, blood pressure, respirations, sneezing, swallowing, and coughing are controlled by which area of the brain? a. Pons b. Midbrain c. Cerebellum d. Medulla oblongata

ANS: D The medulla oblongata makes up the myelencephalon and is the lowest portion of the brainstem. Reflex activities, such as heart rate, respiration, blood pressure, coughing, sneezing, swallowing, and vomiting, are controlled only in this area.

Innervates muscles that move the eye laterally.

Abducens nerve The abducens nerve affects control over the motor fibers to the lateral rectus muscle and the proprioceptor fibers from the same muscle to the brain, allowing the eyes to move laterally.

Fibers emerge from the midbrain, exit from the skull, and extend to the eye.

Oculomotor nerve The oculomotor nerve fibers emerge from the midbrain, exit from the skull, and extend to the eye. These fibers control: (1) the motor fibers to the inferior oblique, superior, inferior, and medial rectus extraocular muscles that direct the eyeball; (2) the levator muscles of the eyelid; (1) the smooth muscles of the iris and ciliary body; and (4) proprioception (sensory) to brain from the extraocular muscles.