Glossary: The Nervous System

abducens nerve
sixth cranial nerve; responsible for contraction of one of the extraocular muscles
alar plate
developmental region of the spinal cord that gives rise to the posterior horn of the gray matter
amygdala
nucleus deep in the temporal lobe of the cerebrum that is related to memory and emotional behavior
anterior column
white matter between the anterior horns of the spinal cord composed of many different groups of axons of both ascending and descending tracts
anterior horn
gray matter of the spinal cord containing multipolar motor neurons, sometimes referred to as the ventral horn
anterior median fissure
deep midline feature of the anterior spinal cord, marking the separation between the right and left sides of the cord
anterior spinal artery
blood vessel from the merged branches of the vertebral arteries that runs along the anterior surface of the spinal cord
arachnoid granulation
outpocket of the arachnoid membrane into the dural sinuses that allows for reabsorption of CSF into the blood
arachnoid mater
middle layer of the meninges named for the spider-web–like trabeculae that extend between it and the pia mater
arachnoid trabeculae
filaments between the arachnoid and pia mater within the subarachnoid space
ascending tract
central nervous system fibers carrying sensory information from the spinal cord or periphery to the brain
axillary nerve
systemic nerve of the arm that arises from the brachial plexus
Broca’s area
region of the frontal lobe associated with the motor commands necessary for speech production and located only in the cerebral hemisphere responsible for language production, which is the left side in approximately 95 percent of the population
Brodmann’s areas
mapping of regions of the cerebral cortex based on microscopic anatomy that relates specific areas to functional differences, as described by Brodmann in the early 1900s
basal forebrain
nuclei of the cerebrum related to modulation of sensory stimuli and attention through broad projections to the cerebral cortex, loss of which is related to Alzheimer’s disease
basal nuclei
nuclei of the cerebrum (with a few components in the upper brain stem and diencephalon) that are responsible for assessing cortical movement commands and comparing them with the general state of the individual through broad modulatory activity of dopamine neurons; largely related to motor functions, as evidenced through the symptoms of Parkinson’s and Huntington’s diseases
basal plate
developmental region of the spinal cord that gives rise to the lateral and anterior horns of gray matter
basilar artery
blood vessel from the merged vertebral arteries that runs along the dorsal surface of the brain stem
brachial plexus
nerve plexus associated with the lower cervical spinal nerves and first thoracic spinal nerve
brain stem
region of the adult brain that includes the midbrain, pons, and medulla oblongata and develops from the mesencephalon, metencephalon, and myelencephalon of the embryonic brain
carotid canal
opening in the temporal bone through which the internal carotid artery enters the cranium
cauda equina
bundle of spinal nerve roots that descend from the lower spinal cord below the first lumbar vertebra and lie within the vertebral cavity; has the appearance of a horse’s tail
caudate
nucleus deep in the cerebrum that is part of the basal nuclei; along with the putamen, it is part of the striatum
central canal
hollow space within the spinal cord that is the remnant of the center of the neural tube
central sulcus
surface landmark of the cerebral cortex that marks the boundary between the frontal and parietal lobes
cephalic flexure
curve in midbrain of the embryo that positions the forebrain ventrally
cerebellum
region of the adult brain connected primarily to the pons that developed from the metencephalon (along with the pons) and is largely responsible for comparing information from the cerebrum with sensory feedback from the periphery through the spinal cord
cerebral aqueduct
connection of the ventricular system between the third and fourth ventricles located in the midbrain
cerebral cortex
outer gray matter covering the forebrain, marked by wrinkles and folds known as gyri and sulci
cerebral hemisphere
one half of the bilaterally symmetrical cerebrum
cerebrum
region of the adult brain that develops from the telencephalon and is responsible for higher neurological functions such as memory, emotion, and consciousness
cervical plexus
nerve plexus associated with the upper cervical spinal nerves
choroid plexus
specialized structures containing ependymal cells lining blood capillaries that filter blood to produce CSF in the four ventricles of the brain
circle of Willis
unique anatomical arrangement of blood vessels around the base of the brain that maintains perfusion of blood into the brain even if one component of the structure is blocked or narrowed
common carotid artery
blood vessel that branches off the aorta (or the brachiocephalic artery on the right) and supplies blood to the head and neck
corpus callosum
large white matter structure that connects the right and left cerebral hemispheres
cranial nerve ganglion
sensory ganglion of cranial nerves
cranial nerve
one of twelve nerves connected to the brain that are responsible for sensory or motor functions of the head and neck
descending tract
central nervous system fibers carrying motor commands from the brain to the spinal cord or periphery
diencephalon
region of the adult brain that retains its name from embryonic development and includes the thalamus and hypothalamus
direct pathway
connections within the basal nuclei from the striatum to the globus pallidus internal segment and substantia nigra pars reticulata that disinhibit the thalamus to increase cortical control of movement
disinhibition
disynaptic connection in which the first synapse inhibits the second cell, which then stops inhibiting the final target
dorsal (posterior) nerve root
axons entering the posterior horn of the spinal cord
dorsal (posterior) root ganglion
sensory ganglion attached to the posterior nerve root of a spinal nerve
dura mater
tough, fibrous, outer layer of the meninges that is attached to the inner surface of the cranium and vertebral column and surrounds the entire CNS
dural sinus
any of the venous structures surrounding the brain, enclosed within the dura mater, which drain blood from the CNS to the common venous return of the jugular veins
endoneurium
innermost layer of connective tissue that surrounds individual axons within a nerve
enteric nervous system
peripheral structures, namely ganglia and nerves, that are incorporated into the digestive system organs
enteric plexus
neuronal plexus in the wall of the intestines, which is part of the enteric nervous system
epineurium
outermost layer of connective tissue that surrounds an entire nerve
epithalamus
region of the diecephalon containing the pineal gland
esophageal plexus
neuronal plexus in the wall of the esophagus that is part of the enteric nervous system
extraocular muscles
six skeletal muscles that control eye movement within the orbit
facial nerve
seventh cranial nerve; responsible for contraction of the facial muscles and for part of the sense of taste, as well as causing saliva production
fascicle
small bundles of nerve or muscle fibers enclosed by connective tissue
femoral nerve
systemic nerve of the anterior leg that arises from the lumbar plexus
fibular nerve
systemic nerve of the posterior leg that begins as part of the sciatic nerve
foramen magnum
large opening in the occipital bone of the skull through which the spinal cord emerges and the vertebral arteries enter the cranium
forebrain
anterior region of the adult brain that develops from the prosencephalon and includes the cerebrum and diencephalon
fourth ventricle
the portion of the ventricular system that is in the region of the brain stem and opens into the subarachnoid space through the median and lateral apertures
frontal eye field
region of the frontal lobe associated with motor commands to orient the eyes toward an object of visual attention
frontal lobe
region of the cerebral cortex directly beneath the frontal bone of the cranium
gastric plexuses
neuronal networks in the wall of the stomach that are part of the enteric nervous system
globus pallidus
nuclei deep in the cerebrum that are part of the basal nuclei and can be divided into the internal and external segments
glossopharyngeal nerve
ninth cranial nerve; responsible for contraction of muscles in the tongue and throat and for part of the sense of taste, as well as causing saliva production
gyrus
ridge formed by convolutions on the surface of the cerebrum or cerebellum
hindbrain
posterior region of the adult brain that develops from the rhombencephalon and includes the pons, medulla oblongata, and cerebellum
hippocampus
gray matter deep in the temporal lobe that is very important for long-term memory formation
hypoglossal nerve
twelfth cranial nerve; responsible for contraction of muscles of the tongue
hypothalamus
major region of the diencephalon that is responsible for coordinating autonomic and endocrine control of homeostasis
indirect pathway
connections within the basal nuclei from the striatum through the globus pallidus external segment and subthalamic nucleus to the globus pallidus internal segment/substantia nigra pars compacta that result in inhibition of the thalamus to decrease cortical control of movement
inferior colliculus
half of the midbrain tectum that is part of the brain stem auditory pathway
inferior olive
nucleus in the medulla that is involved in processing information related to motor control
intercostal nerve
systemic nerve in the thoracic cavity that is found between two ribs
internal carotid artery
branch from the common carotid artery that enters the cranium and supplies blood to the brain
interventricular foramina
openings between the lateral ventricles and third ventricle allowing for the passage of CSF
jugular veins
blood vessels that return “used” blood from the head and neck
kinesthesia
general sensory perception of movement of the body
lateral apertures
pair of openings from the fourth ventricle to the subarachnoid space on either side and between the medulla and cerebellum
lateral column
white matter of the spinal cord between the posterior horn on one side and the axons from the anterior horn on the same side; composed of many different groups of axons, of both ascending and descending tracts, carrying motor commands to and from the brain
lateral horn
region of the spinal cord gray matter in the thoracic, upper lumbar, and sacral regions that is the central component of the sympathetic division of the autonomic nervous system
lateral sulcus
surface landmark of the cerebral cortex that marks the boundary between the temporal lobe and the frontal and parietal lobes
lateral ventricles
portions of the ventricular system that are in the region of the cerebrum
limbic cortex
collection of structures of the cerebral cortex that are involved in emotion, memory, and behavior and are part of the larger limbic system
limbic system
structures at the edge (limit) of the boundary between the forebrain and hindbrain that are most associated with emotional behavior and memory formation
longitudinal fissure
large separation along the midline between the two cerebral hemispheres
lumbar plexus
nerve plexus associated with the lumbar spinal nerves
lumbar puncture
procedure used to withdraw CSF from the lower lumbar region of the vertebral column that avoids the risk of damaging CNS tissue because the spinal cord ends at the upper lumbar vertebrae
median aperture
singular opening from the fourth ventricle into the subarachnoid space at the midline between the medulla and cerebellum
median nerve
systemic nerve of the arm, located between the ulnar and radial nerves
meninges
protective outer coverings of the CNS composed of connective tissue
mesencephalon
primary vesicle of the embryonic brain that does not significantly change through the rest of embryonic development and becomes the midbrain
metencephalon
secondary vesicle of the embryonic brain that develops into the pons and the cerebellum
midbrain
middle region of the adult brain that develops from the mesencephalon
myelencephalon
secondary vesicle of the embryonic brain that develops into the medulla
nerve plexus
network of nerves without neuronal cell bodies included
neural crest
tissue that detaches from the edges of the neural groove and migrates through the embryo to develop into peripheral structures of both nervous and non-nervous tissues
neural fold
elevated edge of the neural groove
neural groove
region of the neural plate that folds into the dorsal surface of the embryo and closes off to become the neural tube
neural plate
thickened layer of neuroepithelium that runs longitudinally along the dorsal surface of an embryo and gives rise to nervous system tissue
neural tube
precursor to structures of the central nervous system, formed by the invagination and separation of neuroepithelium
neuraxis
central axis to the nervous system, from the posterior to anterior ends of the neural tube; the inferior tip of the spinal cord to the anterior surface of the cerebrum
occipital lobe
region of the cerebral cortex directly beneath the occipital bone of the cranium
occipital sinuses
dural sinuses along the edge of the occipital lobes of the cerebrum
oculomotor nerve
third cranial nerve; responsible for contraction of four of the extraocular muscles, the muscle in the upper eyelid, and pupillary constriction
olfaction
special sense responsible for smell, which has a unique, direct connection to the cerebrum
olfactory nerve
first cranial nerve; responsible for the sense of smell
optic nerve
second cranial nerve; responsible for visual sensation
orthostatic reflex
sympathetic function that maintains blood pressure when standing to offset the increased effect of gravity
paravertebral ganglia
autonomic ganglia superior to the sympathetic chain ganglia
parietal lobe
region of the cerebral cortex directly beneath the parietal bone of the cranium
parieto-occipital sulcus
groove in the cerebral cortex representing the border between the parietal and occipital cortices
perineurium
layer of connective tissue surrounding fascicles within a nerve
phrenic nerve
systemic nerve from the cervical plexus that enervates the diaphragm
pia mater
thin, innermost membrane of the meninges that directly covers the surface of the CNS
plexus
network of nerves or nervous tissue
postcentral gyrus
ridge just posterior to the central sulcus, in the parietal lobe, where somatosensory processing initially takes place in the cerebrum
posterior columns
white matter of the spinal cord that lies between the posterior horns of the gray matter, sometimes referred to as the dorsal column; composed of axons of ascending tracts that carry sensory information up to the brain
posterior horn
gray matter region of the spinal cord in which sensory input arrives, sometimes referred to as the dorsal horn
posterior median sulcus
midline feature of the posterior spinal cord, marking the separation between right and left sides of the cord
posterolateral sulcus
feature of the posterior spinal cord marking the entry of posterior nerve roots and the separation between the posterior and lateral columns of the white matter
precentral gyrus
primary motor cortex located in the frontal lobe of the cerebral cortex
prefrontal lobe
specific region of the frontal lobe anterior to the more specific motor function areas, which can be related to the early planning of movements and intentions to the point of being personality-type functions
premotor area
region of the frontal lobe responsible for planning movements that will be executed through the primary motor cortex
prevertebral ganglia
autonomic ganglia that are anterior to the vertebral column and functionally related to the sympathetic chain ganglia
primary vesicle
initial enlargements of the anterior neural tube during embryonic development that develop into the forebrain, midbrain, and hindbrain
proprioception
general sensory perceptions providing information about location and movement of body parts; the “sense of the self”
prosencephalon
primary vesicle of the embryonic brain that develops into the forebrain, which includes the cerebrum and diencephalon
putamen
nucleus deep in the cerebrum that is part of the basal nuclei; along with the caudate, it is part of the striatum
radial nerve
systemic nerve of the arm, the distal component of which is located near the radial bone
reticular formation
diffuse region of gray matter throughout the brain stem that regulates sleep, wakefulness, and states of consciousness
rhombencephalon
primary vesicle of the embryonic brain that develops into the hindbrain, which includes the pons, cerebellum, and medulla
sacral plexus
nerve plexus associated with the lower lumbar and sacral spinal nerves
saphenous nerve
systemic nerve of the lower anterior leg that is a branch from the femoral nerve
sciatic nerve
systemic nerve from the sacral plexus that is a combination of the tibial and fibular nerves and extends across the hip joint and gluteal region into the upper posterior leg
sciatica
painful condition resulting from inflammation or compression of the sciatic nerve or any of the spinal nerves that contribute to it
secondary vesicle
five vesicles that develop from primary vesicles, continuing the process of differentiation of the embryonic brain
sigmoid sinuses
dural sinuses that drain directly into the jugular veins
somatosensation
general senses related to the body, usually thought of as the senses of touch, which would include pain, temperature, and proprioception
spinal accessory nerve
eleventh cranial nerve; responsible for contraction of neck muscles
spinal nerve
one of 31 nerves connected to the spinal cord
straight sinus
dural sinus that drains blood from the deep center of the brain to collect with the other sinuses
striatum
the caudate and putamen collectively, as part of the basal nuclei, which receive input from the cerebral cortex
subarachnoid space
space between the arachnoid mater and pia mater that contains CSF and the fibrous connections of the arachnoid trabeculae
subcortical nucleus
all the nuclei beneath the cerebral cortex, including the basal nuclei and the basal forebrain
substantia nigra pars compacta
nuclei within the basal nuclei that release dopamine to modulate the function of the striatum; part of the motor pathway
substantia nigra pars reticulata
nuclei within the basal nuclei that serve as an output center of the nuclei; part of the motor pathway
subthalamus
nucleus within the basal nuclei that is part of the indirect pathway
sulcus
groove formed by convolutions in the surface of the cerebral cortex
superior colliculus
half of the midbrain tectum that is responsible for aligning visual, auditory, and somatosensory spatial perceptions
superior sagittal sinus
dural sinus that runs along the top of the longitudinal fissure and drains blood from the majority of the outer cerebrum
sympathetic chain ganglia
autonomic ganglia in a chain along the anterolateral aspect of the vertebral column that are responsible for contributing to homeostatic mechanisms of the autonomic nervous system
systemic nerve
nerve in the periphery distal to a nerve plexus or spinal nerve
tectum
region of the midbrain, thought of as the roof of the cerebral aqueduct, which is subdivided into the inferior and superior colliculi
tegmentum
region of the midbrain, thought of as the floor of the cerebral aqueduct, which continues into the pons and medulla as the floor of the fourth ventricle
telencephalon
secondary vesicle of the embryonic brain that develops into the cerebrum
temporal lobe
region of the cerebral cortex directly beneath the temporal bone of the cranium
terminal ganglion
autonomic ganglia that are near or within the walls of organs that are responsible for contributing to homeostatic mechanisms of the autonomic nervous system
thalamus
major region of the diencephalon that is responsible for relaying information between the cerebrum and the hindbrain, spinal cord, and periphery
third ventricle
portion of the ventricular system that is in the region of the diencephalon
tibial nerve
systemic nerve of the posterior leg that begins as part of the sciatic nerve
transverse sinuses
dural sinuses that drain along either side of the occipital–cerebellar space
trigeminal ganglion
sensory ganglion that contributes sensory fibers to the trigeminal nerve
trigeminal nerve
fifth cranial nerve; responsible for cutaneous sensation of the face and contraction of the muscles of mastication
trochlear nerve
fourth cranial nerve; responsible for contraction of one of the extraocular muscles
ulnar nerve
systemic nerve of the arm located close to the ulna, a bone of the forearm
vagus nerve
tenth cranial nerve; responsible for the autonomic control of organs in the thoracic and upper abdominal cavities
ventral (anterior) nerve root
axons emerging from the anterior or lateral horns of the spinal cord
ventricles
remnants of the hollow center of the neural tube that are spaces for cerebrospinal fluid to circulate through the brain
vertebral arteries
arteries that ascend along either side of the vertebral column through the transverse foramina of the cervical vertebrae and enter the cranium through the foramen magnum
vestibulocochlear nerve
eighth cranial nerve; responsible for the sensations of hearing and balance