nervous system organization

chapter 3

afferent

conducting toward a central nervous system area

amygdala

an almond-shaped collection of nuclei in the base of the temporal lobe; the part of the limbic system that participates in emotional and species-typical behaviours

anterior cerebral artery

a vessel originating from the carotid artery that irrigates the medial and dorsal parts of the cortex, including the orbitofrontal and dorsolateral frontal regions, and the anterior cingulate cortex, corpus callosum and striatum

anterior root

a nerve composed of fibres carrying motor information from the anterior part of the human spinal cord

astroglia

a star-shaped glial cell that provides structural support to neurons in the central nervous system and transport substances between neurons and blood vessels

basal ganglia

subcortical forebrain nuclei that connect to the thalamus and midbrain and coordinate voluntary movements of the limbs and body

bilateral

applying to both sides of the body

biploar neuron

neurons with processes at both poles; characteristic especially of retinal cells

brodmann’s map

a map of the cerebral cortex

blood-brain barrier

tight junctions between capillary cells that block entry of an array of substances, including toxins into the brain

central sulcus

a fissure that runs from the dorsal border of each hemisphere

cerebellum

a major structure of the hindbrain that is specialized for learning and coordinating skilled movements.

cerebral aqueduct

a connection between the third and fourth ventricles that drains cerebrospinal fluid from the fourth ventricle into the circulatory system at the base of the brainstem

cingulate cortex

a strip of three to four layered limbic cortex that lies just above the corpus callosum along the medial walls of the cerebral hemispheres

contralateral

residing in the side of the body opposite the reference point

cranial nerves

a set of 12 pairs of nerves that convey sensory and motor signals to and form the head

dermatome

a body segment corresponding to a segment of the spinal cord

diencephalon

the region of the brain that includes the hypothalamus, thalamus and epithalamus

distal

distant from some point

efferent

conducting away from the central nervous system area and toward a muscle or gland

ependymal cells

glial cells that make and secrete cerebrospinal fluid and form the lining of the ventricle

epithalamus

a collection of nuclei that forms the phylogenetically most primitive region of the thalamus; includes pineal gland, which secretes the hormone melatonin that influences daily and seasonal body rhythms

ganglia

a collection of nerve cells that function somewhat like a brain

gray matter

any brain area composed predominantly of cell bodies and capillaries

hemorrhagic stroke

a severe stroke that results from a burst vessel bleeding into the brain

hippocampus

a distinctive limbic-system structure that lies in the anterior medial region of the temporal lobe; participates in species-specific behaviours, memory, and spatial navigation and is vulnerable to the effects of stress

hypothalamus

a collection of nuclei located below the thalamus in the diencephalon; controls behaviour including movement,t feeding, sexual activity, sleeping, emotional expression, temperature regulation and endocrine regulation

inferior colliculi

nuclei of the midbrain tectum that receive auditory projections and mediate orientation to auditory stimuli

interneurons

any neuron lying between a sensory neuron and a motor neuron

ipsilateral

residing in the same side of the body as the point of reference

ischemia

deficient blood flow to the brain due to functional constriction or actual obstruction of a blood vessel by a clot

limbic system

disparate forebrain structures lying between the neocortex and the brainstem that form a functional system controlling affective and motivated behaviours and certain forms of memory; includes cingulate cortex, amygdala, hippocampus, hypothalamus

meninges

3 layers of protective tissue - dura mater, arachnoid, and pia mater - that encase the brain and spinal cord

mesencephalon

middle brain; one of the three primary embryonic vesicles, which in the embryonic mammalian brain subsequently comprises the tectum and tegmentum

metencephalon

the anterior part of the mammalian rhombencephalon; composed of the cerebellum and pons

microglia

glial cells that originate in the blood, aid in cell repair, and scavenge debris in the nervous system

middle cerebral artery

an artery that runs along the length of the lateral fissure to irrigate the lateral surface of the cortex, including the ventral part of the frontal lobe, most of the parietal lobe and the temporal lobe

motor neurons

Unit formed by motor neurons and the muscle fibre to which their axon terminations are connected

myelencephalon

The spinal brain, the posterior part of the mammalian rhombencephalon, including the medulla oblongata and fourth ventricle

myelin

a lipid substance that forms an insulating sheath around certain nerve fibres; formed by oligodendroglia in the central nervous system and by schwann cells in the peripheral nervous system

neocortex

the newest later of the brain, forming the outer layer, or “new bark”; has four to six layers of cells

nerves

a large collection of axons coursing together outside the central nervous system

nuclei

a spherical structure in the soma of a cell; contains DNA and is essential to cell functions; also, a cluster of cells that can be identified histologically and has specific functions in mediating behaviour

oligodendroglia

glial cells in the central nervous system that myelinate axons

parapelgic

a person whose spinal cord has been cut, making them unable to have control over their legs

parasympathetic nerves

calming nerves of the autonomic nervous system that enable the body to rest and digestion

posterior cerebral artery

a vessel that irrigates the ventral and posterior surfaces of the cortex, including the occipital lobe and hippocampal formation

posterior root

a nerve composed of fibres carrying sensory information that entres each segment of the posterior spinal cord

precentral gyrus

the gyrus lying in front of the central sulcus

prosencephalon

the frontal brain, the most anterior part of the embryonic mammalian brain

proximal

close to some point

quadriplegic

paralysis of the legs and arms due to spinal cord damage

reflexes

a specific movement that depends only on a simple spinal- cord circuit and elicited by specific forms of sensory stimulation

reticular formation

a mixture of nuclei and fibres that runs through the centre of the brainstem, extending from the spinal cord to the thalamus; assoicated with sleep-wake behaviour and behavioural arousal

reticular matter

any nervous system area composed of intermixed cell bodies and axons

rhombencephalon

a posterior chamber of the embryonic mammalian brain, which divides into the mesencephalon and myelencephalon

schwann cells

glial cells in the peripheral nervous system system that myelinate sensory and motor axons

secondary areas

a cortical region that receives inputs from the primary areas and is thought to participate in more complex sensory and perceptual or motor functions

sensory receptor

a cell that transduces sensory information into nervous system activity

somatosensory neuron

a neuron that projects from the body’s sensory receptors into the spinal cord; dendrite and axon are connected, which speeds information conduction because messages do not have to pass through the cell body

stroke

the sudden appearance of neurological symptoms as a result of severe interruption of blood flow

substantia nigra

nuclei in the midbrain containing the cell bodies of dopamine-containing axons that connect to the forebrain and are important in rewarding behaviours

superior colliculi

bilateral nuclei of the midbrain tectum that receive projections from the retina of the eye and mediate visually related behaviour

sympathetic nerves

arousing nerves of the autonomic nervous system that enable the body to fight or flee or engage in vigorous activity

tectum

the roof of the midbrain, located above the cerebral aqueduct; consists of the superior and inferior colliculi, which mediate whole-body responses to visual and auditory stimuli

tegmentum

the floor of the midbrain; located below the cerebral aqueduct, contains a collection of sensory and motor tracts and nuclei with movements-related

telencephalon

the end brain; includes the mammalian cerebral cortex, basal ganglia, limbic system and olfactory bulbs

thalamus

a group of nuclei in the diencephalon that integrates information from all sensory systems and projects it into the appropriate cortical regions

tracts

a large collection of axons coursing together within the central nervous system

ventricles

a cavity of the brain that contains cerebrospinal fluid

white matter

areas of the nervous system rich in fat-sheathed neural axons that form the connections between brain cells