Unit 6

Voluntary

actions of the body that are under volitional control (not automatic) 

Automaticity

patterns of responses that no longer require highly specific motor control, but are relegated to automated patterns. 

Background activity

involuntary muscular contraction that supports action or movement, providing the foundation upon which voluntary movement is placed. 

Tonicity

contraction of musculature to maintain muscle tone. 

Superficial sensation

sensation arising from the stimulation of the surface of the body (temperature, pain, touch) 

Deep sensation

sensation from within the body (muscle tension, joint position, proprioception, muscle pain, pressure, vibration) 

Proprioception

the body’s position in space 

Functional nervous system

includes the autonomic and somatic nervous systems. 

Anatomical nervous system

includes the central and peripheral nervous systems. 

Central nervous system

includes the cerebrum, cerebellum, subcortical structures, brain stem, and spinal cord. 

Peripheral nervous system

includes the spinal nerves, cranial nerves, and sensory receptors. 

Autonomic nervous system

governs involuntary activities of the visceral muscles, including glandular secretions, heart function, and digestive function. 

Sympathetic system

subsystem of the ANS that response to stimulation through energy expenditure. 

Parasympathetic system

subsystem of the ANS that returns the ANS to the resting state following a sympathetic response. 

Afferent

ascending, sensory pathways. 

Efferent

descending, motor pathways. 

Somatic nervous system

involves the aspects of bodily function that are under conscious and voluntary control, including control of all skeletal muscles. 

Pyramidal system

Subdivision of the somatic nervous system arising from pyramidal cells of the motor strip of the cerebral cortex, largely responsible for the initiation of voluntary motor acts; also referred to as the direct activation pathway. 

Extrapyramidal system

Subdivision of the somatic nervous system arising from the premotor region of the frontal lobe responsible for the background tone and movement supporting the primary movements; also referred to as the indirect activation pathway.  

Neurons

communicating tissue of the nervous system. 

Glial cells

neural tissue with a wide variety of functions in the nervous system, including recycling of neurotransmitters, waste removal (phagocytosis), and encapsulation of damaged areas of tissue; types of glial cells include astrocytes, Schwann cells, oligodendrocytes, microglia, and ependymal cells. 

Soma 

cell body of the neuron; contains metabolic organelles. 

Dendrite

receptor region of the neuron. 

Excitation

stimulation of the neuron that causes an increase of activity of the tissue stimulated (i.e., increases the likelihood of another action potential). 

Inhibition

stimulation of the neuron that causes a decrease of activity of the tissue stimulated (i.e., decreased the likelihood of another action potential). 

Axon hillock

generator site for the action potential; connection between soma and axon. 

Myelin sheath 

insulator of the axon facilitating a more rapid action potential. 

Telodendria

processes extended from the end of the axon. 

Terminal end buttons

endings of telodendria that contain synaptic vesicles (thus neurotransmitters). 

Synaptic vesicles

contain neurotransmitters. 

Neurotransmitters

compounds responsible for activating the next neuron in a chain of neurons. 

Synaptic cleft 

the gap between two neurons. 

Presynaptic neuron

neurons on the front-end of the synapse; neuron sending the action potential. 

Postsynaptic neuron

neurons on the back-end of the synapse; neuron receiving the action potential. 

Receptor sites

receivers on the post-synaptic neuron that are stimulated by neurotransmitters. 

Astrocytes

type of glial cell forming a bridge between neurons and capillaries; part of the BBB 

Blood-brain barrier

BBB; a membranous filter system that prohibits some toxins from passing from the cerebrovascular system to neurons. 

Microglia

type of glial cell performing phagocytosis (i.e., removal of waste materials) 

Schwann cells

type of glial cell making myelin in the PNS. 

Oligodendrocytes

type of glial cell making myelin in the CNS. 

Interneurons

type of neurons that communicate exclusively with other neurons. 

Meninges

three membrane layers that cover and protect your brain and spinal cord. 

Dura mater

tough, bi-layered, most-superficial lining of the meninges. 

Epidural space

potential space superficial to the dura mater. 

Arachnoid mater

covering through which many blood vessels pass; lacey, spiderly structural separating the dura mater from the innermost meningeal lining, the pia mater. 

Subarachnoid space

contains cerebrospinal fluid (CSF) and blood vessels; located between the arachnoid mater and the pia mater. 

Pia mater

thin, membranous covering that closely follows the contour of the brain. 

Cerebrospinal fluid

CSF; provides cushion for the delicate and dense neural tissue as well as some nutrient delivery and waste removal; flows through the ventricles and canals around the CNS. 

Choroid Plexus

aggregate of tissue that produces CSF. 

Ventricles

each of the four fluid-filled cavities in the brain. 

Lateral ventricles

largest of the ventricles; composed of four spaced bounded superiorly by the corpus collosum that extend into each o the lobes of the cerebrum. 

Third ventricle

unpaired medial cavity between the left and right thalami and hypothalamic. 

Fourth ventricle

shaped roughly like a diamond, projecting upward from the central canal of the spinal cord and lower medulla. 

Cerebrum

the largest portion of the human brain, containing neural components and structures responsible for voluntary and conscious function. 

Cerebral hemispheres

paired structures of the CNS, consisting of the frontal, parietal, occipital, temporal, and insular lobes. 

Cortex

outer covering of the cerebrum consisting of gray matter. 

Gray matter

unmyelinated neurons of the CNS. 

White matter

myelinated neurons of the CNS. 

Longitudinal fissure

fissure that separates the right and left hemispheres

Gyri

plural of gyrus, significant prominence of outfolding of tissue. 

Sulci

plural of sulcus, significant infolding of tissue. 

Fissures

a relatively deep groove. 

Lateral sulcus

a.k.a. Sylvian fissure, fissure dividing temporal lobe from frontal and anterior parietal lobes. 

Sylvian fissure

a.k.a. lateral sulcus. 

Central sulcus  

a.k.a. Rolandic fissure, fissure dividing frontal and parietal lobes.  

Rolandic fissure 

a.k.a. central sulcus. 

Insula

region located deep to the lateral sulcus, responsible for motor speech planning, perception of taste, processing emotion, our perception of self, and development of compassion and empathy. 

Frontal lobe

largest of the cerebral lobes, involved in planning, initiation, and inhibition of voluntary motion, as well as cognitive function (in particular executive functions). 

Broca’s area

located in the left hemisphere inferior frontal gyrus adjacent to the lateral sulcus, responsible for expressive language processing and motor speech planning. 

Premotor cortex

the region of the cerebral cortex anterior to the precentral gyrus involved in motor speech planning. 

Primary motor strip

a.k.a. precentral gyrus, the region immediately anterior to the central sulcus and considered to be the primary activation region for muscles. 

Supplementary motor area

part of the premotor cortex, involved in complex motor acts, including rehearsal and initiation of motor function. 

Parietal lobe

primary reception site for the somatic (body) sense.  

Primary sensory strip

a.k.a. postcentral gyrus, primary site of sensory input. 

Supramarginal gyrus 

portion of inferior parietal lobe involved in phonological short-term memory and (in the case of the right hemisphere specifically) visuospatial processing. 

Angular gyrus

portion of inferior parietal lobed involved in language and number processing. 

Temporal lobe

site of auditory reception and receptive language processing. 

Heschl’s gyrus

located on the anterior third of the left hemisphere superior temporal gyrus, location of the brain to which all auditory information is projected. 

Wernicke’s area

located on the posterior third of the left hemisphere superior temporal gyrus, responsible for receptive language processing. 

Occipital lobe

region responsible for receiving visual stimulation. 

Limbic system

includes several subcortical structures working together to control motivation, sex drive, emotional behavior, and affect (mood). 

Projection fibers

tracts running to and from the cortex, brain stem, and spinal cord that connect the cortex to distant locations. 

Corona radiata

mass of projection fibers running from and to the cortex. 

Internal capsule

condensed projection fibers coursing down forming an L-shape as it passes between subcortical structures to the brainstem. 

Association fibers

fibers providing communication between regions of the same hemisphere. 

Arcuate fasciculus

association fibers connecting posterior and anterior language regions of the left hemisphere. 

Commissural fibers

fibers running from one hemisphere to the other. 

Basal ganglia

group of cell bodies intimately related to the control of background movement and initiation of movement patterns. 

Hippocampal formation

strongly involved in memory consolidation. 

Thalamus

sensory relay station for sensory information directed toward the cerebral cortex. 

Cerebrovascular system

vascular supply of the brain. 

Carotid arteries

a pair of large blood vessels on either side of the neck providing oxygenated blood to the face and brain. 

Carotid bifurcation

point where the common carotid artery splits into the internal and external carotid arteries. 

Internal carotid arteries

an artery that supplies oxygenated blood to the brain, eyes, and other cranial structures. 

External carotid arteries

an artery that supplies oxygenated blood to the neck and face. 

Anterior cerebral arteries

arises from the circle of Willis and the internal carotid artery supplying oxygenated blood to most midline portions of the frontal lobes and superior medial parietal lobes of the brain.  

Middle cerebral arteries

arises from the internal carotid artery coursing laterally into the lateral sulcus where it branches to perfuse the cerebral cortex. 

Vertebral arteries

a pair of major arteries in the neck that supply blood to the brain and spine.  

Basilar artery

a large vessel that supplies oxygen-rich blood to the back of the brain, including the brainstem, cerebellum, and occipital lobes; formed by the vertebral arteries joining at the junction of the medulla and pons. 

Posterior cerebral arteries

terminal branches of the basilar artery and supply the occipital lobes and posteromedial temporal lobes.