The Neuroscience on the Web Series:
Glossary of Neuroscience Terms Q-S




rami communicantes:
the rami of the autonomic nervous system are the axons of its pre-ganglionic and ganglionic cells
red nucleus:
a structure of the midbrain, connects the cerebellum to the thalamus and spinal cord
reflex arc:
a reflexive behavior that occurs when a message from sensory fibers causes a motor reaction directly, without the impulse having to first be sent to the brain (e.g., the reflex arc of the spinal nerves)
release phenomenon:
the rapid firing of motor neurons; the basal ganglia acts to inhibit this
rigidity :
If the limbs of a Parkinson's patient are moved passively, the muscles will often contract involuntarily, causing rigidity. This rigidity may be constant or intermittent. Intermittent rigidity is called cogwheel rigidity.
restiform bodies (inferior cerebellar peduncles):
one of the three fiber bundles called cerebellar peduncles that connect the cerebellum to the brain stem; the inferior cerebellar peduncle connects the cerebellum with the vestibular nuclei located in the lower pons and medulla, and with the reticular formation; proprioceptive information from the upper body (information that travels along the dorsospinocerebellar tract) enters the cerebellum on the inferior cerebellar peduncle
reticulocerebellar tract:
a fiber tract that carries information received by the reticular nuclei in the brain stem from the cortex, spinal cord, vestibular system, and red nucleus to the cerebellum
reticulospinal tract:
a fiber tract that runs from the reticular nuclei of the pons and medulla to the spinal nerves; it carries information related to the functioning of the autonomic nervous system (e.g., circulation of the blood, dilation of blood vessels, respiration, and visceral activity); it is also involved in somatic motor control like the rubrospinal tract and also plays an important role in the control of autonomic functions.
reticular activating system (ascending reticular formation):
the component of the reticular formation that is responsible for the sleep-wake cycle; it mediates various levels of alertness
reticular formation:
a set of interconnected nuclei that are found throughout the brain stem; the dorsal tegmental nuclei are located in the midbrain, the central tegmental nuclei are located in the pons, and the central and inferior nuclei are located in the medulla; the reticular formation has two components, the ascending reticular formation and the descending reticular formation
Reversible Ischemic Neurological Defect(RINDs):
RINDs are lengthy TIAs, . The term RIND is usually applied to attacks that continue for more than 12 hours without interruption, although some RINDs may last for several days. As is the case with TIAs, RINDs resolve in complete recovery, however some neurologists do not consider them temporary. (There is some evidence that RINDs do cause some subtle neurological damage, but these minor changes are nothing like the types of disabilities seen after "real" strokes.)

Sometimes, events that last for twenty-four hours are called TIAs rather than RINDs, so there is some inconsistency in the application of this terminology.
rhinencephalon (limbic system or limbic lobe):
the most ancient and primitive part of the brain; it is composed of both cortical and subcortical structures located on the medial, inferior surfaces of the cerebral hemispheres; the limbic system is involved in the processing of olfactory stimuli, emotions, and memory
right hemisphere syndrome:
blockages of the right middle cerebral artery due to right hemispher lesions whic can cause left side neglect, which is an impairment in the ability to recognize and respond to stimuli on the left side of the body, prosopagnosia or the inability to recognize faces, and various cognitive problems, including agnosia.
right hemianopsia:
visual field deficit due to left hemisphere lesion, the disorder of vision that most often accompanies aphasia
"toward the beak," rostral can mean the same as superior, and is an antonym of caudal
rotational trauma:
occurs when impact causes the brain to move within the cranium at a different velocity than the skull. This results in a shearing of axons by the bones of the skull. Because this type of injury damages neural connections rather than gray matter, it can affect a wide array of cerebral functions and should therefore is likely to cause diffuse injury.
rubrospinal tract:
a fiber tract, the fibers of which descend from the cerebellum through the red nucleus to synapse with the spinal nerves; this tract carries information important for skeletal muscle control and the regulation of muscle tone for posture  


sagittal cut:
a cut that runs parallel to the medial cut, but divides the brain into two unequal parts
salpingopharyngus muscle (of the Pharynx):
with the stylopharyngus m. makes up the internal longitudinal layer of the pharynx
secondary auditory areas (auditory association areas):
two areas, located in the temporal lobes, which contribute to the ability to comprehend speech
secondary visual areas:
areas of the occipital lobe, superior to the primary visual cortex, that integrate visual information and give meaning to what is being seen by relating it to prior experience and knowledge; damage to this area can cause visual agnosia
second order neurons:
there are several types, lower motor neurons; the cranial and spinal nerves; the cell bodies of second order neurons are located in the neuraxis, but their axons can synapse with the muscles of the body
semantic aphasia:
see Wernicke's Aphasia
septal region:
subcortical component of the limbic system; it includes the septal nuclei
septum pellucidum:
a double walled structure located between the corpus callosum and the fornix
association fibers that connect areas that are located within the same lobe
silent aspiration:
aspiration of food and liquids without coughing, can occur as a result of neurological damage. (If food or liquid enters the respiratory system of a normal, healthy individual, it induces coughing.) Silent aspiration can cause pneumonia, with a temperature spike being the first indication that food or liquids are entering the lungs.
cell body; the part of the neuron that contains the cell's nucleus and cytoplasm
spastic dysarthria:
results from lesions to the pyramidal tract, characterized by "Generalized hypertonicity, weakness, immobility, abnormal force physiology, and exaggerated reflexes of virtually all muscles of the speech mechanism produce obvious dysfunction of the articulation subsystem. Speech is slow-labored, and imprecise articulatory efforts, compounded by disturbances of respiration; resonation, and phonation often render speech unintelligible" Dworkin (1991, p.188).
spinal cord:
the part of the central nervous system that lies below the magnum foramen, and that extends downward to just above the cauda equina; it contains the cell bodies of the spinal nerves and their afferent and efferent fibers
Spinal Accessory Nerve (CN. XI):
Motor Component innervates the palatopharyngeus muscle which depresses the velum and constricts the pharynx, and so innervates the muscularis uvula which tenses the velum. It, along with CN.X, innervates the levator veli palatini.
(CN. XI is strictly a motor nerve.)
spinal nerves:
thirty-one pairs of mixed nerves (sensory and motor) that are second order lower motor neurons and form part of the final common pathway; they also form a reflex arc; their motor fibers originate on the ventral part of the spinal cord at the anterior horns of grey matter and their roots of sensory fibers are located on the dorsal side of the spinal cord in the posterior root ganglia; these join together to form the spinal nerves after they exit the spinal column; the spinal nerves receive only contralateral innervation from first order neurons
spinal tap (lumbar puncture):
a diagnostic procedure in which a needle is inserted in the lower lumbar section of the vertebral canal to obtain a sample of cerebrospinal fluid
a general term that means "narrowing", in this course it is used to describe arterial narrowing
stripping action:
pharyngeal constrictor muscles help move food down toward the esophagus via this action.(This process should not be confused with peristalsis which is the wave-like motions of muscles that occur in the esophagus. In some of the literature, the action of the pharyngeal constrictor muscles is mistakenly called peristalsis.)
stylopharyngus muscle (of the Pharynx):
with the salpingopharyngus m. makes up the internal longitudinal layer of the pharynx
the "artery of stroke"; a branch of the middle cerebral artery; the striata supplies blood to the corpus striatum
or cerebral vascular accident is a temporary or permanent loss of functioning of brain tissue caused by an interruption in the cerebral blood supply. Strokes can  be divided into the categories here are two principle kinds of strokes, ischemic and hemorrhagic within which they are categorized completed or progressive.
Subarachnoid bleeding:
According to Love and Webb (1992), bleeding into the subarachnoid space is often the result of aneurysm. According to FitzGerald (1997), berry aneurysms bleed directly into the subarachnoid space, because they originate in the circle of Willis. Strokes in those under 40 are often the result of ruptured aneurysm (FitzGerald, 1997). TBI is less likely to cause subarachnoid bleeding
subarachnoid space:
a space that lies between the arachnoid mater and pia mater; it is filled with cerebrospinal fluid; all blood vessels entering the brain and cranial nerves pass through the subarachnoid space
subcallosal gyrus:
a cortical area (a gyrus) that is considered to be a part of the limbic system; it is located immediately inferior to the corpus callosum
Subcortical Aphasia:
Lesions in the anterior subcortical area involving the limb of the internal capsule and putamen are associated with sparse language output and impaired articulation. Posterior subcortical lesions are associated with fluent forms of aphasia, while lesions of the thalamus may cause a global aphasia.
subdural bleeding:
According to Stedman (1997), subdural hemorrhaging, or the extravasation of blood in the potential space between the dura mater and the arachnoid membrane, causes hematomas to form. Chronic hematomas may become encapsulated by neomembranes. This is often over the frontal and temporal lobes. As this type of bleeding results from damage to veins, which contain less blood than arteries, subdural bleeding is much slower than epidural bleeding. According to Pires (1984), sometimes days or weeks pass before any symptoms of hemorrhaging appear. According to Bhatnagar and Andy (1995), subdural hematoma is usually due to traumatic brain injury, with bleeding from ruptured blood vessels in the arachnoid tissue below the dura mater. If not removed the blood will compress neural tissue causing infarction.
subdural space:
a potential space between the dura mater and the arachnoid mater
substantia nigra:
a group of dark colored cell bodies in the midbrain which produce dopamine; the substantia nigra is part of the extrapyramidal system
a groove between two gyri
refers to the upper parts of the nervous system
superior brachium conjunctivum (superior cerebellar peduncle):
the fiber tract that connects the cerebellum to the midbrain; it contains efferent fibers from the dentate, emboliform, and globose nuclei that send feedback to the motor cortex, and afferent fibers that carry proprioceptive information to the cerebellum from the lower body (information that is carried upward along the spinal cord on the ventrospinocerebellar tract)
superior colliculi:
structures of the midbrain that relay visual information to the lateral geniculate bodies of the thalamus
superior sagittal sinus:
a vein-like sinus that runs across the top of the brain in an anterior-posterior direction, it is from dura mater
supraglottic swallow:
patient is told to take a breath and hold it while swallowing and then cough after the swallow. This results in the voluntary closure of the vocal folds before, during and after the swallow.
supra supra-glottic swallow:
This technique closes the entrance to the airway at the level of the arytenoid cartilages. The patient follows the same procedure as with the supra-glottic swallow, but "bears down while holding his breath."
supramarginal gyrus:
Brodmann's area 40
swallowing center:
believed to be located in the medulla within the nuclei of the reticular formation; specifically the nucleus ambiguous When the swallow response is initiated, this center causes messages to be sent to the glossopharyngeal, the vagus, and the hypoglossal nerves. The glossopharyngeal is considered the major nerve for the swallowing center.
sympathetic nervous system:
a division of the autonomic nervous system; it prepares the body for fight or flight