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meninges
membranes that cover the brain & the spinal cord
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dura mater
Outermost meninx--tough connective tissue attached to the inside of the cranial cavity
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arachnoid mater
Middle meninx--thin, web-like membrane that lacks blood vessels covers the brain and spinal cord
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Subarachnoid space
the space between the arachnoid and pia maters; contains cerebrospinal fluid
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pia mater
meninx closest to the brain--thin with many nerves & blood vessels that nourish the cells of the brain & spinal cord.
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choroid plexus
tiny, reddish, cauliflowerlike masses of capillaries from the pia mater that secrete CSF. Project into the cavities of the ventricles
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ventricle
interconnected cavities in the cerebral hemispheres and brainstem. Continuous with the central canal of the spinal cord & filled with CSF
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ascending tract
nerve that conducts sensory impulses to the brain
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descending tracts
nerve tract that conducts motor impulses from the brain to motor neurons and then to muscles & glands
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fasciculus gracilis
fasciculus cuneatus
- Conduct sensory impulses from the skin, muscles, tendons, and joints to the brain
- (ascending tract)
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spinothalamic tracts
- conduct sensory impulses associated with pain, temperature, touch, and pressure to the brain
- (ascending tract)
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spinocerebellar tracts
- conduct sensory impulses required for the coordination of muscle movements from muscles of lower limbs & trunk to the cerebellum
- (ascending tracts)
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corticospinal tracts
- conducts motor impulses associated with voluntary movements from the brain to skeletal muscles
- (descending tracts)
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reticulospinal tracts
- conducts motor impulses associated with the maintenance of muscle tone & the activity of sweat glands from the brain
- (descending tracts)
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rubrospinal tract
- conduct motor impulses associated with muscular coordination and the maintenance of posture from the brain
- (descending tracts)
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cerebrum
largest part of the mature brain--provides higher mental functions
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corpus callosum
deep bridge of nerve fibers that connects the cerebral hemispheres
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falx cerebri
dura mater that separates the cerebral hemispheres
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gyrus/gyri
ridges or convolutions that mark the cerebrum
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sulcus
a shallow to deep groove
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fissure
a very deep groove
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longitudinal fissure
fissure that separates the right and left cerebral hemispheres
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transverse fissure
fissure that separates the cerebrum from the cerebellum
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sensory areas
areas in lobes of the cerebrum that interpret impulses from sensory receptors, producing feelings or sensations
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association areas
areas in lobes of the cerebrum that are neither sensory nor motor. They connect with each other and other brain structures. They analyze and interpret sensory experiences and help provide memory, reasoning, verbalizing, judgement, and emotions
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motor areas
areas in lobes of the cerebrum that correspond with movement of skeletal muscle
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short term memory
short-term: "working memory" are thought to be electrical--neurons connect in a circuit so that the last stimulates the next. As long as the pattern continues, the thought is remembered
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long-term memory
long-term: probably changes the structure or function of neurons to enhance synaptic transmission
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memory consolidation
conversion of short-term memories to long-term memories
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long-term synaptic potentiation
A theory that the near simultaneous repeated stimulation of the same neurons strengthens their synaptic connections. Therefore, more frequent action potentials are triggered in postsynaptic cells in the hippocampus of the temporal lobe
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basal nuclei
masses of gray matter deep within the cerebral hemispheres: 1) the caudate nucleus 2) putamen 3) globus pallidus. They produce dopamine and interact with the motor cortex, thalamus, and cerebellum which facilitates voluntary movements.
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diencephalon
part of the brain in the region of the third ventricle that includes the thalamus and hypothalamus
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thalamus
the selective gateway for sensory impulses ascending from other parts of the nervous system to the cerebral cortex. It receives all sensory impulses (except sense of smell) and channels them to appropriate regions of the cortex for interpretation.
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hypothalamus
receives and sends impulses to the cerebral cortex, thalamus, and parts of the brainstem. It maintains homeostasis by regulating visceral activities and linking the nervous and endocrine systems.
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limbic system
Connected structures (parts of cerebral cortex, the hypothalamus, thalamus, basal nuclei, and other deep nuclei) in the brain that controls emotional experiences emotional experience and expression.
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brainstem
Connects the brain to the spinal cord & contains the midbrain, pons, and medulla oblongata.
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Midbrain (mesencephalon)
a short section of brainstem between diencephalon and the pons.
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pons
a rounded bulge on the underside of the brainstem, separating the midbrain from the medulla oblongata. Dorsal portion of the pons mostly consists of longitudinal nerve fibers. Relays information from the medulla oblongata and the cerebrum
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medulla oblongata
enlarged continuation of the spinal cord.
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reticular formation
a complex network of nerve fibers associated with tiny islands of gray matter. Connects centers of the hypothalamus, basal nuclei, cerebellum, and cerebrum with fibers in all the major ascending and descending tracts. Filters incoming sensory impulses, regulates motor activities, inhibits or enhances certain spinal reflexes.
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slow-wave versus rapid eye movement (REM)
- Slow wave sleep: restful, dreamless, accompanied by reduced blood pressure and respiratory rate. May last 70-90 minutes.
- REM: "paradoxical sleep" meaning some areas of the brain are active--dream sleep. Usually last 5-15 minutes.
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cerebellum
large mass of tissue located inferior to the cerebrum
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cerebellar cortex
gray matter that covers the cerebellum. Contains a tree-like pattern of white matter called the arbor vitae
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cerebellar peduncles
- three pairs of nerve tracts that allows the cerebellum with other parts of the CNS.
- inferior peduncles: brings sensory information concerning position of body parts to the cerebellum via the spinal cord & medulla oblongata
- middle peduncles: transmit information from the cerebral cortex about the desired position of these body parts
- superior peduncles: cerebellum sends correcting impulses from the dentate nucleus to the midbrain
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peripheral nervous system
nerves that branch from the CNS to other body parts
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cranial nerves vs spinal nerves
- cranial nerves: arise from the brain
- spinal nerves: arise from the spinal cord
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somatic nervous system
oversees conscious activities--consists of cranial and spinal nerve fibers that connect the CNS to the skin & skeletal muscles
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autonomic nervous system
oversees subconscious actions--fibers that connect the CNS to viscera such as the heart, stomach, intestines, and various glands
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epineurium
the outermost layer of connective tissue surrounding bundles of nerve fibers (peripheral nerve)
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perineurium
encloses each bundle of nerve fibers (fascicle)
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endoneurium
surrounds individual nerve fibers
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sensory nerves vs. motor nerves vs. mixed nerves
- sensory nerves: nerves that have only fibers of sensory neurons, conducting impulses into the brain or spinal cord
- motor nerves: only involved in motor control
- mixed nerves: contain both sensory & motor nerves
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general somatic efferent fibers (1)
carry motor impulses outward from the brain or spinal cord to skeletal muscles and stimulate them to contract
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general visceral efferent fibers (2)
carry motor impulses outward from the brain or spinal cord to various smooth muscles and glands associated with internal organs, causing certain muscles to contract or glands to secrete
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general somatic afferent fibers (3)
carry sensory impulses inward to the brain or spinal cord from receptors in the skin and skeletal muscles
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general visceral afferent fibers (4)
carry sensory impulses to the CNS from blood vessels and internal organs
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special somatic efferent fibers (1)
carry motor impulses outward from the brain to the muscles used in chewing, swallowing, speaking, and forming facial expressions
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special visceral afferent fibers (2)
carry sensory impulses inward to the brain from the olfactory and taste receptors
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special somatic afferent fibers (3)
carry sensory impulses inward to the brain from the receptors of sight, hearing, and equilibrium
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olfactory (I)
sensory; fibers transmit impulses associated with smell
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optic (II)
sensory; fibers transmit impulses associated with vision
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oculomotor (III)
- mixed nerves:
- sensory--proprioceptors;
- motor-- muscles that raise eyelids, move the eye, focus lens, adjust light entering eye
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trochlear (IV)
- mixed nerves:
- sensory--proprioceptors
- motor--muscles that move the eyes
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trigeminal (V)
- mixed nerve
- opthalmic division (sensory): surface of eyes, tear glands, scalp, forehead, and upper eyelids
- maxillary division (sensory): upper teeth, upper gum, upper lip, palate, and skin of face
- mandibular division (sensory): scalp, skin of jaw, lower teeth, lower gum, and lower lip; (motor): muscles of mastication and muscles in floor of mouth
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abducens (VI)
- primarily motor--impulses to muscles that move the eyes
- some sensory--proprioceptors
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facial (VII)
- mixed nerves:
- sensory--taste receptors
- motor--muscles of facial expression, tear glands, and salivary glands
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vestibulocochlear (VIII)
- sensory;
- vestibular branch--equilibrium receptors in ear
- cochlear branch--hearing receptors in ear
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glossopharyngeal (IX)
- mixed:
- sensory--pharynx, tonsils, tongue, and carotid arteries
- motor--salivary glands and muscles of pharynx (swallowing)
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vagus nerve (X)
- mixed:
- motor--muscles of speech and swallowing; autonomic motor to viscera of thorax and abdomen
- sensory--pharynx, larynx, esophagus, and viscera of thorax and abdomen
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accessory (XI)
- primarily motor
- cranial branch--muscles of soft palate, pharynx, and larynx
- spinal branch--muscles of neck and back
- some proprioception
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hypoglossal (XII)
- primarily motor: muscles of tongue
- some proprioception
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dorsal root
axons of sensory neurons bringing info into spinal cord through dorsal root ganglia (cell bodies of sensory neurons)
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ventral root
axons of motor neurons whose cell bodies are found in the spinal cord
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nerve plexus
- complex networks formed by anterior branches of spinal nerves
- fibers of various spinal nerves are sorted out and recombined
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autonomic nervous system
- functions without conscious effort
- controls visceral activities
- sympathetic & parasympathetic
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autonomic nerve fibers
- all neurons are motor (efferent)
- preganglionic fibers: axons of preganglionic neurons; cell bodies found in CNS
- postganglionic fibers: axons of postganglionic neurons; cell bodies found in ganglia
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