Chapter 3 - Anatomy of the Nervous System Flashcards
Central nervous system (CNS)
The portion of the nervous system within the skull and spine
Peripheral nervous system (PNS)
The portion of the nervous system outside the skull and spine
Somatic nervous system (SNS)
The part of the peripheral nervous system that interacts with the external environment
Afferent nerves
Nerves that carry sensory signals to the central nervous system
Efferent nerves
Nerves that carry motor signals from the central nervous system to the skeletal muscles or internal organs
Autonomic nervous system (ANS)
The part of the peripheral nervous system that participates in the regulation of the body’s internal environment
Sympathetic nerves
Those motor nerves of the autonomic nervous system that project from the central nervous system in the lumbar and thoracic region areas of the spinal cord
Parasympathetic nerves
Those autonomic motor nerves that project from the brain to the sacral region of the spinal cord
Cranial nerves
The 12 pairs of nerves extending from the brain (e.g., optic nerves, olfactory nerves, and vagus nerves)
Glial cells
Several classes of nonneural cells of the nervous system
Oligodendrocytes
Glial cells that myelinate axons of the central nervous system; also known as oligodendroglia
Myelin
A fatty insulating substance
Myelin sheaths
Coverings on the axons of some neurons that are rich in myelin and increase the speed and efficiency of axonal conduction
Schwann cells
The glial cells that compose the myelin sheaths of PNS axons and promote the regeneration of PNS axons
Microglia
Glial cells that respond to injury or disease by engulfing cellular debris and triggering inflammatory responses
Astrocytes
Large, star-shaped glial cells that play multiple roles in the central nervous system
Golgi stain
A neural stain that completely darkens a few of the neurons in each slice of tissue, thereby revealing their silhouettes
Niss1 stain
A neural stain that has an affinity for structures in neuron cell bodies
Electron microscopy
A microscopy technique used to study the fine details of cellular structure
Anterior
Toward the nose end of a vertebrate
Posterior
Toward the tail end of a vertebrate or toward the back of the head
Dorsal
Toward the surface of the back of a vertebrate or toward the top of the head
Ventral
Toward the chest surface of a vertebrate or toward the bottom of the head
Medial
Toward the midline of the body
Lateral
Away from the midline of the body of a vertebrate, toward the body’s lateral surfaces
Superior
Toward the top of the primate head
Inferior
Toward the bottom of the primate head or brain
Proximal
Close to something
Distal
Far from something
Horizontal sections
Any slices of brain tissue cut in a plane that are parallel to the top of the brain
Frontal sections
Any slices of brain tissue cut in a plane that is parallel to the face; also termed coronal sections
Sagittal sections
Any slices of brain tissue cut in a plane that is parallel to the side of the brain
Cross section
Section cut at a right angle to any long, narrow structure of the central nervous system
Gray matter
Portions of the nervous system that are gray because they are composed largely of cell bodies and unmyelinated interneurons
White matter
Portions of the nervous system that are white because they are composed largely of myelinated axons
Dorsal horns
The two dorsal arms of the spinal gray matter
Meninges
The three protective membranes that cover the brain and spinal cord (singular meninx)
Dura mater
The tough outer meninx
Arachnoid membrane
The meninx that is located between the dura mater and the pia mater and has the appearance of a gauzelike spiderweb
Subarachnoid space
The space beneath the arachnoid membrane, which contains many large blood vessels and cerebrospinal fluid
Pia mater
The delicate, innermost meninx
Cerebrospinal fluid (CSF)
The fluid that fills the subarachnoid space, the central canal, and the cerebral ventricles
Central canal
The small cerebrospinal fluid-filled channel that runs the length of the spinal cord
Cerebral ventricles
The four cerebrospinal fluid-filled internal chambers of the brain: the two lateral ventricles, the third ventricle, and the fourth ventricle
Choroid plexuses
The networks of capillaries that protrude into the ventricles from the pia mater and produce cerebrospinal fluid
Blood-brain barrier
The mechanism that impedes the passage of toxic substances from the blood into the brain
Ventral horns
The two ventral arms of the spinal gray matter
Dorsal root ganglia
Structures just outside the spinal cord that are composed of the cell bodies of dorsal root axons
Brain stem
The part of the brain on which the cerebral hemispheres rest; in general, it regulates reflex activities that are critical for survival (e.g., heart rate and respiration)
Myelencephalon (medulla)
The most posterior of the five major divisions of the brain; the medulla
Reticular formation
A complex network of about 100 tiny nuclei that occupies the central core of the brain stem from the posterior boundary of the myelencephalon to the anterior boundary of the midbrain. Sometimes referred to as “little net” or as the reticular activating system.
Metencephalon
One of the five major divisions of the brain; it includes the pons and cerebellum
Pons
The metencephalic structure that creates a bulge on the ventral surface of the brain stem
Cerebellum
A metencephalic structure that is thought to participate in the storage of memories of learned sensorimotor skills
Mesencephalon
One of the five major divisions of the brain; it is composed of the tectum and tegmentum
Tectum
The dorsal surface of the midbrain; the roof
Inferior colliculi
The structures of the tectum that receive auditory input from the superior olives
Superior colliculi
Two of the four nuclei that compose the tectum; they receive major visual input
Tegmentum
The ventral division of the mesencephalon; it includes part of the reticular formation, substantia nigra, and red nucleus
Periaqueductal gray
The gray matter around the cerebral aqueduct, which contains opiate receptors and activates a descending analgesia circuit
Cerebral aqueduct
A narrow channel that connects the third and fourth ventricles
Substantia nigra
The midbrain nucleus whose neurons project via the nigrostriatal pathway to the striatum of the basal ganglia; it is part of the mesotelencephalic dopamine system
Red nucleus
A structure of the sensorimotor system that is located in the tegmentum of the mesencephalon
Diencephalon
One of the five major divisions of the brain; it is composed of the thalamus and hypothalamus
Thalamus
The large two-lobed diencephalic structure that constitutes the anterior end of the brain stem; many of its nuclei are sensory relay nuclei that project to the cortex
Massa intermedia
The neural structure located in the third ventricle that connects the two lobes of the thalamus
Sensory relay nuclei
Those nuclei of the thalamus whose main function is to relay sensory signals to the appropriate areas of cortex
Lateral geniculate nuclei
The six-layered thalamic structures that receive input from the retinas and transmit their output to the primary visual cortex
Medial geniculate nuclei
The auditory thalamic nuclei that receive input from the inferior colliculi and project to primary auditory cortex
Ventral posterior nuclei
A thalamic relay nucleus in both the somatosensory and gustatory systems
Hypothalamus
The diencephalic structure that sits just below the anterior portion of the thalamus
Pituitary gland
The gland that dangles from, and is controlled by, the hypothalamus
Optic chiasm
The X-shaped structure on the inferior surface of the diencephalon; the point where the optic nerves decussate
Decussate
To cross over to the other side of the brain
Contralateral
Projecting from one side of the body to the other
Ipsilateral
On the same side of the body
Mammillary bodies
The pair of spherical nuclei that are located on the inferior surface of the hypothalamus
Telencephalon
The most superior of the brain’s five major divisions
Cerebral cortex
The layer of neural tissue covering the cerebral hemispheres of humans and other mammals
Neurons
Cells of the nervous system that are specialized for the reception, conduction, and transmission of electrochemical signals
Multipolar neuron
A neuron with more than two processes extending from its cell body
Unipolar neuron
A neuron with one process extending from its cell body
Bipolar neuron
A neuron with two processes extending from its cell body
Interneurons
Neurons with short axons or no axons at all, whose function is to integrate neural activity within a single brain structure
Nuclei
The DNA-containing structures of cells; also, clusters of neuronal cell bodies in the central nervous system (singular nucleus)
Ganglia
Clusters of neuronal cell bodies in the peripheral nervous system (singular ganglion)
Tracts
Bundles of axons in the central nervous system
Nerves
Bundles of axons in the peripheral nervous system
Fissures
The large furrows in a convoluted cortex
Sulci
Small furrows in a convoluted cortex
Gyri
The cortical ridges that are located between fissures or sulci
Longitudinal fissure
The large fissure that separates the two cerebral hemispheres
Cerebral commissures
Tracts that connect the left and right cerebral hemispheres
Corpus callosum
The largest cerebral commissure
Central fissure
The large fissure that separates the frontal lobe from the parietal lobe
Lateral fissure
The large fissure that separates the temporal lobe from the frontal lobe
Frontal lobe
The most anterior of the four cerebral lobes
Parietal lobe
One of the four cerebral lobes; it is located just posterior to the central fissure
Temporal lobe
One of the four major cerebral lobes; it lies adjacent to the temples and contains the hippocampus and amygdala
Occipital lobe
The most posterior of the four cerebral lobes; its function is primarily visual
Precentral gyrus
The gyrus located just anterior to the central fissure; its function is primarily motor
(plural: precentral gyri)
Postcentral gyrus
The gyrus located just posterior to the central fissure; its function is primarily somatosensory
(plural: postcentral gyri)
Superior temporal gyri
The plural of superior temporal gyrus
Neocortex
Six-layered cerebral cortex of relatively recent evolution; it constitutes 90 percent of human cerebral cortex
Pyramidal cells
Large multipolar cortical neurons with a pyramid-shaped cell body, an apical dendrite, and a very long axon
Stellate cells
Small star-shaped cortical interneurons
Columnar organization
The functional organization of the neocortex in vertical columns; the cells in each column form a mini-circuit that performs a single function
Hippocampus
A structure of the medial temporal lobes that plays a role in various forms of memory
Limbic system
A collection of interconnected nuclei and tracts that ring the thalamus
Amygdala
A structure in the anterior temporal lobe, just anterior to the hippocampus; plays a role in emotion
Cingulate cortex
The cortex of the cingulate gyri, which are located on the medial surfaces of the frontal lobes
Cingulate gyri
Large gyri located on the medial surfaces of the frontal lobes, just superior to the corpus callosum
(singular: cingulate gyrus)
Fornix
The major tract of the limbic system; it connects the hippocampus with the septum and mammillary bodies
Septum
A midline nucleus of the limbic system, located near the anterior tip of the cingulate cortex
Basal ganglia
A collection of subcortical nuclei (e.g., striatum and globus pallidus)
Caudate
The tail-like structure that is part of the striatum
Putamen
A structure that is joined to the caudate by a series of fiber bridges; together the putamen and caudate compose the striatum
Striatum
A structure of the basal ganglia that is the terminal of the dopaminergic nigrostriatal pathway
Globus pallidus
A structure of the basal ganglia that is located between the putamen and thalamus
