Section I: Organization & Structure of the Nervous System

Chapter 1: Organization & Cells of the Nervous System

Following an injury in the workplace that affected a patient’s right arm, causing loss of movement of that limb, it was determined that the injury had disrupted axoplasmic transport in the sensory and motor nerves of that limb. Which of the following statements accurately reflects a fundamental property of axonal transport?

A. Large membranous organelles are transported by slow axonal transport.

B. Cytosolic proteins are transported by fast axonal transport.

C. Retrograde transport is generally limited to a fixed rate of movement of particles.

D. Anterograde transport is dependent on microtubules.

E. The motor protein kinesin specifically governs slow axonal transport.

D. The vast majority of axonal proteins are synthesized in the cell soma. Axonal transport includes fast and slow axonal transport from the cell soma along the axon to the presynaptic terminus. Fast axonal transport is for transport of large organelles and vesicles and depends on microtubules and microtubule motors (kinesins for anterograde transport and dyneins for retrograde transport). Slow axonal transport is for cytosolic and cytoskeletal proteins. (Recent studies suggest that slow transport may also involve microtubules, but the cytosolic and cytoskeletal cargoes may stop more along the way.)

Which of the following best describes the characteristic of white matter?

A. White matter contains neuronal cell bodies, dendrites, and synapses.

B. White matter contains myelinated axons, astrocytes, and oligodendrocytes.

C. White matter contains pericytes and ependymal cells.

D. White matter contains all neurons and glia in the central nervous system (CNS).

E. White matter includes all tracts and nerves in the CNS and peripheral nervous system (PNS).

B. White matter is found in only the CNS (not the PNS) and contains myelinated axons, white matter astrocytes, and the myelinating oligodendrocytes. Pericytes line the brain capillaries (and white matter does have capillaries), but ependymal cells are located only in the ventricles.

Which of the following best describes the functions of astrocytes?

A. Astrocytes form cerebral blood vessels and the blood–brain barrier.

B. Astrocytes line the brain ventricles and form the brain capillaries.

C. Astrocytes provide energy substrates for neurons and can regulate blood flow.

D. Astrocytes are the major immune cells of the CNS and become “reactive glia” following injury.

E. Astrocytes form the postsynaptic component of the tripartite synapse.

C. Brain capillaries are formed by vascular endothelial cells surrounded by pericytes. Astrocytes form end feet on these capillaries; transport a variety of nutrients, including energy substrates; and release substances that can regulate blood flow. Microglia are the immune cells of the CNS, and neuronal processes such as dendrites or dendritic spines form the postsynaptic component of the synapse. Astrocytes can surround the synapse, forming the tripartite synapse.

Which of the following best describes neurons and their processes?

A. All neurons are signaling cells that communicate via electrical and/or chemical information with other neurons or target cells.

B. All neurons are multipolar cells, with 1 large axon and multiple branched dendrites.

C. All neuronal cell bodies are located in the CNS, but their axons can extend into the PNS.

D. All axons are myelinated and highly branched at their termini.

E. All dendrites contain small protrusions called dendritic spines, which increase the surface area of the dendrite.

A. No matter its function, be it a sensory neuron, motor neuron, or interneuron, all neurons form synapses or contacts with target cells and signal or communicate with their targets. Depending on their function, different neurons can have very different types of morphologies, and not all have an axon or branched dendrites. Neuronal cell bodies can be present in the PNS (dorsal root ganglia and autonomic ganglia); not all axons are myelinated (about half are not) or branched; and not all dendrites are spiny.

Which of the following best characterizes the blood–brain barrier (BBB)?

A. The presence of the BBB prevents hydrophobic molecules such as steroids and gases from entering into the neural tissue of the brain.

B. The BBB prevents entry of most pathogenic cells but allows the majority of immune cells into the brain to prevent infection.

C. The majority of CNS neurons and astrocytes come in direct contact with brain capillaries to ensure access to energy substrates and oxygen.

D. The BBB forms during neurulation to prevent migration of PNS neurons into the CNS.

E. The BBB is formed by vascular endothelial cells and pericytes, with astrocytic end feet surrounding them.

E. The BBB does not prevent entry of hydrophobic molecules, only hydrophilic molecules. The BBB prevents the entry of the majority of pathogenic and immune cells. The majority of neurons do not contact the brain capillaries and hence depend on astrocytes for essential nutrients and energy substrates. The BBB forms late in development after neurogenesis and gliogenesis. As described earlier, the BBB is formed by vascular endothelial cells, which are surrounded by pericytes.

Chapter 2: Development of the Nervous System

Which of the following best describes the process of neural induction (NI)?

A. NI involves the release of morphogens by the notochord that inhibit bone morphogenetic proteins (BMP) signaling in the overlying ectoderm.

B. NI involves morphogens released by the neural plate to the underlying notochord.

C. In NI. morphogens stimulate the developing gastrula to form the 3 primary germ layers.

D. NI occurs following neurulation, during segmentation and flexure.

E. NI involves induction of the mesoderm to form neural mesoderm.

A. Neural induction occurs after gastrulation, when the notochord at the midline (and surrounding paraxial mesoderm) releases morphogens to the overlying ectoderm. These morphogens inhibit the BMP signaling pathway in the ectoderm and instruct the ectoderm to form the neural plate (neuroectoderm). Once the plate is formed, it undergoes neurulation followed by segmentation and flexure.

Which of the following best characterizes development of the neural tube?

A. Errors in neuronal and glial migration produce microcephaly.

B. Errors in proliferation and expansion of the neural tube produce neural tube defects.

C. It forms from the neural plate in the process of “neural flexure” following gastrulation.

D. It gives rise to the vast majority of neurons and glia of the central nervous system (CNS).

E. The lumen of the neural tube forms the meninges and blood supply of the brain and spinal cord.

D. Errors in neurogenesis and gliogenesis cause microcephaly. Errors in neuronal migration cause cortical malformations such as heterotopias. Neural tube defects result from errors in closing of the neural tube. The neural tube forms from the neural plate via the process of neurulation. The neural tube gives rise to almost all the neurons and glia of the CNS (a small number of neurons that end up in the CNS arise from placodes or neural crest). The lumen of the neural tube forms the brain ventricles and central canal.

Which of the following best describes regionalization of the neural tube during development?

A. The myelencephalon gives rise to the cerebellum.

B. The mesencephalon gives rise to the midbrain.

C. The telencephalon gives rise to the thalamus and hypothalamus.

D. The diencephalon gives rise to the forebrain.

E. The metencephalon gives rise to the pons and medulla oblongata.

B. The myelencephalon gives rise to the medulla oblongata. The mesencephalon gives rise to the midbrain. The telencephalon gives rise to the cerebral hemispheres and several subcortical structures. The diencephalon gives rise to the thalamus and hypothalamus. The metencephalon gives rise to the pons and cerebellum.

Which of the following best characterizes neurogenesis and gliogenesis?

A. For most regions of the cerebral cortex, glial cells are generated and differentiate before neurons.

B. The majority of neurons are produced from the neural tube, whereas the majority of glia are produced from neural crest cells.

C. Both neurons and glia develop from neural stem cells and neural progenitor cells.

D. Both neurogenesis and gliogenesis occur predominantly postnatally.

E. Neurogenesis and gliogenesis begin before neurulation and closure of the neural tube.

C. For most cortical regions, neurons develop before glia. The vast majority of CNS neurons and glia develop from the neural tube, whereas all the PNS neurons and glia develop from neural crest cells. Neural stem cells and neural progenitor cells are the precursors of both neurons and glia during neurogenesis and gliogenesis. Both neurogenesis and gliogenesis occur both prenatally and postnatally. Neurogenesis and gliogenesis occur after neurulation.

Synaptogenesis involves the formation of synapses, which are:

A. formed only between neuronal axons and dendrites.

B. eliminated by apoptosis during the prenatal critical period.

C. stable structures that are formed predominantly during prenatal development.

D. important for neuronal migration along radial glial cells.

E. dynamic structures that can undergo synaptic refinement and be modified by experience.

E. Synapses form between presynaptic axons and their targets, which can be other neurons (on dendrites, the cell soma and other axons) or muscles or glands. Apoptosis refers to cell death, and although some are lost, not all synapses are eliminated during critical periods. Synapses are dynamic structures that are formed both prenatally and postnatally and in the adult CNS. Radial glial cells guide axons during migration before synapses form. Synapses are dynamic structures that undergo synaptic plasticity and can form or be eliminated, weakened, or strengthened.

Chapter 3: Functional Anatomy of the Nervous System I: Cerebrum & Subcortical Structures

Which of the following statements best describes the cerebrum?

A. The cerebrum is derived from telencephalon, forms the largest part of the brain, and consists of the left and right cerebral hemispheres, which are separated by the central sulcus.

B. Each of the 4 main anatomic lobes—the frontal, parietal, occipital, and temporal lobes—contains a significant area dedicated to sensory and motor functions.

C. The locations of primary, secondary, and tertiary gyri and sulci are invariant among human individuals.

D. The right and left cerebral hemispheres are exact anatomic and functional mirror images of each other, although the right hemisphere receives sensory input from and controls the left side of the body, whereas the left hemisphere receives sensory input from and controls the right side of the body.

E. In addition to 4 anatomic lobes, 2 functional lobes, called the insular and limbic lobes, located deep within the brain, have been characterized in humans.

E. The left and right cerebral hemispheres are separated by the longitudinal fissure (also known as the deep sagittal fissure). Only the parietal, occipital, and temporal lobes contain substantial cortical areas dedicated to sensory processing, and only the frontal lobe has substantial cortical areas dedicated to motor function. However, because they are all well connected, all the lobes do contribute to sensory processing and motor function. The locations of the primary gyri and sulci are very similar among humans, but the secondary and tertiary gyri and sulci can be located differentially among individuals. The right and left hemispheres are not functionally identical because some functions such as language are lateralized and/or more prominent on 1 side of the brain. The insular lobe and limbic lobe are considered the fifth and sixth “functional” lobes but are not visible from the exterior view of the brain.

Which of the following statements best characterizes the cerebral cortex?

A. Human brain contains only 1 type of cerebral cortex, called neocortex, that is composed of 6 layers.

B. Individual association areas receive substantial inputs from both primary sensory and primary motor areas.

C. The smallest functional unit of the neocortex is a cylinder of neurons approximately 2 to 3 mm in height and approximately 0.5 mm in diameter, called a cortical column.

D. The human neocortex represents approximately 25% of the cerebral gray matter.

E. The cerebral hemispheres contain the cerebral cortex, which is the thin layer of gray matter that is covered by the cerebral white matter and meninges.

C. The human brain contains both neocortex (6 layers) and allocortex (3 to 4 layers); for example, the hippocampus is allocortex. Association cortices are mainly involved in processing either sensory or motor information, but not both. The cortical column is considered the smallest functional unit, and columns have been identified in both visual and somatosensory cortex. The human neocortex is large and represents about 75% of cerebral gray matter. The cortical gray matter lies on top of the cerebral white matter and underneath the meninges.

Which of the following best characterizes structures in the temporal lobe?

A. The amygdala is an integration center that is critical for the processing of mainly pleasant emotions and euphoria.

B. The hippocampus, entorhinal cortex, and perirhinal cortex are critical for encoding and storing all long-term declarative and spatial memories.

C. The olfactory cortex is a type of neocortex that receives inputs from the olfactory bulb and olfactory nerve via relay from the thalamus.

D. The auditory cortex is involved in perceiving sounds, assigning meaning to those sounds, and remembering sounds.

E. The ventral regions of the temporal lobe form the dorsal stream, or “where” pathway involved in visual processing that aids in the processing of object location and movement.

D. The amygdala processes many emotions, including pleasant and negative emotions such as fear. Although the hippocampus and associated structures are required for encoding declarative and spatial memories, most explicit memories are thought to be stored in many other areas of the cerebral cortex. Olfactory sensory information is not relayed by way of the thalamus. The primary and secondary auditory cortices are located in the temporal lobe. The ventral regions of the temporal lobe form the ventral stream, or “what” pathway involved in visual processing that aids in object and facial recognition.

Which of the following best describes the thalamus?

A. The thalamus transmits sensory information to the cerebral cortex and is involved in cognitive functions, but is rarely involved in providing information for motor control.

B. The gateway to the cerebral cortex, the thalamus is located between the cerebral cortex and midbrain/brainstem, adjacent to the basal ganglia, and dorsal to the cerebellum, with extensive connections with these regions and the spinal cord.

C. The thalamus contains a single nucleus with specialized subdomains with specific connections to the cerebral cortex, basal ganglia, brainstem, and cerebellum.

D. The thalamus regulates basic life- and species-sustaining functions such as fluid balance, energy metabolism, thermoregulation, and drinking, feeding, and reproductive behaviors.

E. Every sensory system involves relay of information from ascending tracts or cranial nerves to the thalamus, which then transmits sensory information to the specific primary sensory cortex.

B. As the “gateway” to the cerebral cortex, the thalamus transmits sensory, motor, and cognitive information between the cerebral cortex and the spinal cord, basal ganglia, brainstem, and cerebellum. The thalamus contains at least 60 individual nuclei that form specific connections. The basic life functions listed are the job of the hypothalamus. As mentioned earlier, the thalamus does not relay information from the olfactory nerve.

Which of the following statements best describes the basal ganglia (BG)?

A. The BG are involved in the control and coordination of voluntary motor movements, decisions about motor actions, procedural learning, motivation, and reward.

B. Anatomically, the BG include the striatum (formed from the caudate nucleus and putamen), globus pallidus, substantia nigra, hypothalamus, and thalamus.

C. The BG form direct connections with the cerebral cortex and cerebellum for rapid exchange of motor initiation and reward information.

D. The BG are associated with the acquisition of habits and are the main region linked to declarative memory.

E. Loss of neurons in the BG is associated with all forms of dementia, including Alzheimer disease, Huntington disease, amyotrophic lateral sclerosis (ALS), and Parkinson disease.

A. The BG control voluntary movements including motor initiation and motivation-based movements and procedural (a type of implicit) learning and is involved in cognition of motivation and reward. Anatomically, the BG do not include the thalamus. The BG communicate with the cerebral cortex by way of the thalamus; they do not have direct input to the cerebral cortex. The BG are not required for declarative memory, only for nondeclarative/procedural memory. Loss of neurons in the substantia nigra, a component of the BG, is associated with only Parkinson disease and Huntington disease.

Chapter 4: Functional Anatomy of the Nervous System II: The Brainstem, Cerebellum, Spinal Cord, Peripheral Nervous System, & Supporting Systems

Which of the following best describes the brainstem?

A. The brainstem includes the basal ganglia, midbrain, pons, and medulla.

B. The transmission of the majority of sensory and motor information between the cerebral cortex and spinal cord (SC) requires relay by brainstem nuclei.

C. Functions of the brainstem include the regulation of sleep, respiration, heart rate, swallowing, and bladder control.

D. Damage to the brainstem by injury or stroke often leads to a loss of consciousness but is not life threatening.

E. The brainstem houses both sensory and motor white matter tracts, and half (6 of 12) of the cranial nerve nuclei.

C. The brainstem includes the midbrain, pons, and medulla but not the basal ganglia (although some anatomists may include the diencephalon). Voluntary motor information that controls body movement and sensory information from the body are transmitted via white matter tracts that travel through the brainstem but do not require relay there. The brainstem is required for life-sustaining control of breathing, sleep, and other functions. Damage to the brainstem often lead to loss of consciousness and is often life threatening, especially because of the loss of breathing control. The brainstem houses sensory and motor tracts and the majority (10 of 12) of cranial nerve nuclei.

Which of the following best describes the cerebellum?

A. The cerebellum is connected to the cerebral cortices via the midbrain through 3 paired white matter tracts located in the cerebral peduncles.

B. The main functions for the cerebellum are initiation of movements, action selection, motivation, and reward-based motor learning.

C. The cerebellum contains 4 functional regions called the vestibulocerebellum, spinocerebellum, cerebrocerebellum, and bulbarcerebellum.

D. Damage to the cerebellum usually leads to Parkinson-like symptoms.

E. In the cerebellum, the cerebellar cortex receives the majority of inputs, whereas the majority of outputs occur via the deep cerebellar nuclei.

E. The cerebellum receives inputs from the cerebral cortices via the pons through the cerebellar peduncles. The main functions of the cerebellum are in control and coordination of movement, posture and balance, motor learning, and some cognitive functions. The cerebellum contains only 3 functional regions, as there is no bulbar cerebellum. Damage to the cerebellum leads to loss of coordination of movement, abnormal gait, and inability to judge distances.

Which of the following statements is not true regarding the SC?

A. Enclosed in the vertebral canal, the SC is protected by meninges and the vertebral column and surrounds the central canal.

B. The SC is divided into cervical, thoracic, lumbar, sacral, and coccygeal regions along its length.

C. The SC contains white matter tracts and gray matter regions that transmit and relay motor signals from the central nervous system (CNS) to the body and sends sensory signals from the peripheral nervous system to the CNS.

D. Motor axons exit the SC via dorsal roots, whereas sensory axons enter the SC via ventral roots, forming 31 spinal nerve pairs along the length of the SC.

E. The peripheral nerves assemble from branches of the spinal nerves and innervate the body and limbs.

D. Answer choice D is not true because motor axons exit the SC via the ventral roots, whereas axons enter the SC via the dorsal roots.

Which of the following best describes the brain ventricular system and central canal (CC)?

A. The ventricles contain the arachnoid mater and villi, which resorb cerebrospinal fluid (CSF).

B. The lining of the ventricles and choroid plexus within them produce CSF.

C. The third and fourth ventricles lie within the brainstem.

D. The ventricles and CC are derived from neural crest cells during development.

E. CSF flows from the lateral ventricles to the subarachnoid space via the cisterna magna.

B. The ventricles contain the choroid plexus and are lined with ependymal cells, which both synthesize CSF. Only the cerebral aqueduct and fourth ventricle lie within the brainstem since the third ventricle is surrounded by the thalamus. The ventricles and CC are formed from the lumen of the neural tube. CSF flows from the lateral ventricles to the third ventricle to the fourth ventricle and then via the cisterna magna to the subarachnoid space.

Which of the following best describes the vasculature in the CNS?

A. The blood supply to the brain and SC depends on 2 branches from the dorsal aorta.

B. The vertebral arteries supply blood to the anterior part of the brain.

C. The internal carotid arteries supply blood to the posterior part of the brain.

D. In the brain, blood is circulated by arteries, arterioles, veins, and venules, but capillaries are absent.

E. The main outflow from the brain is the vertebral venous plexus.

A. The blood supply to the brain and spinal cord depends on 2 paired branches of the dorsal aorta (the internal carotid arteries arise from bifurcation of the left and right common carotid arteries, and the vertebral arteries are branches of the left and right subclavian arteries). The vertebral arteries supply the posterior part of the brain. The internal carotid arteries supply the anterior part of the brain. In addition to arteries, arterioles, veins, and venules, there are many capillaries that supply the brain. The main outflow from the brain is the jugular vein.