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153 Cards in this Set

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There are 31 spinal nerves
8 cervical12 thoracic5 lumbar5 sacral1 coccygeal
The dorsal root of each spinal nerve is
Sensory
The ventral root of each spinal nerve is
Motor
The spinal ganglion is a collection of nerve cell bodies
On the dorsal root of the spinal nerve
Dorsal column medial lemniscus pathwayFasciculus gracilusFasciculus cuneatus1st - Fibers ascend in dorsal columns and terminate in Fibers decussate and form the 2nd - The medial lemniscus ascends to the 3rd - From the VPL fibers project through the posterior limb of the internal capsule to the Damage above decussation results in Damage in the spinal cord (below the decussation)
Conscious proprioception, tactile discrimination, vibration sensation, form recognition, joint and muscle sensationLower extremitiesUpper extremitiesCaudal medulla (gracile and cuneate nuclei)Medial lemniscus Ventral posteriolateral nucleus of the thalamus (VPL) Post central gyrus (3,1,2) primary somatosensory cortexContralateral lossIpsilateral loss
Lateral spinothalamic tract1st order neurons found in the2nd order neurons decussate in the3rd order neurons project through theLesion of the tract causes
Pain and temperature sensationDorsal root ganglion – project through the dorsolateral tract of Lissauer – synapse in the dorsal hornVentral white commosure and ascend in the contralateral lateral funiculus – terminate in the VPLPosterior limb of the internal capsule to areas 3,1,2Contralateral loss of pain and temperature below the lesion
Lateral corticospinal tract Arise from layer V of the cerebral cortexFibers in the medulla travel in the85-90% of fibers cross at the level of the10-15% of fibers do not crosslesion above the motor decussation results inlesion in spinal cord results in
Voluntary skilled motor activity from upper limbsNot fully developed until second year of life (Babinski’s sign)Premotor cortex (area 6)Primary cortex (area 4)Primary sensory cortex (3,1,2)Medullary pyramids pyramidal decussation (continue as lateral corticospinals)anterior corticospinals contralateral spastic paresis + Babinskiipsilateral spastic paralysis + Babinski
Neural plate is formed by the thickening of the
Ectoderm at the midline (3wks)
The neural tube produces the
CNS – brain and spinal cord
Derivatives of neural crest include
Ganglia, glia, adrenal medulla, melanocytes
The cells of the adrenal medulla are called
Chromaffin cells – release epi and nor epi
The mantle layer of the neural tube becomes the
Gray matter of the spinal cord
The mantle layer is divided into the
Alar plate (sensory) and the basal plate (motor)
The alar plate forms the
Posterior horn of gray (sensory)
The basal plate forms the
Lateral and anterior horns of gray (motor)
The marginal layer of the neural tube becomes the
White matter of the spinal cord
Anterograde degeneration occurs in the segment
of nerve fiber distal to the trama (Wallerian)
Retragrade degeneration occurs in the segment
of the nerve proximal to the trauma and the cell body
Regenerated nerve fibers have about
80% the dia. and conduction velocity of the original fiber
The major contributing ion to the resting potential is
K+, Na+ has little effect
The threshold potential is when the
Na+ influx begins to exceed the K+ efflux
Inhibitory synaptic currents are carried by
K+ or Cl- channels
Excitatory synaptic currents are carried by
Na+, Ca++ or K+
The poster funiculus contains the
Fasciculus gracilis and fasciculus cuneatus
The lateral funiculus contains the
Anterior and posterior spinocerebellars, spinotectal, lateral spinothalamic, lateral corticospinal and rubrospinal
The anterior funiculus contains the
Anterior spinothalamic, anterior corticospinal, tectospinal, vestibulospinal and reticulospinal
There are 3 neurons in ascending(sensory) pathways1st order2nd order3rd order
Spinothalamic, fasciculus gracilus and cuneatus, posterior spinocerebellar and anterior spino cerebellarCell body in dorsal root ganglionConnects 1st and 3rdCell body in thalamus and travels to cortex
Descending tractsPyramidal tractsExtrapyramidal tracts
Lateral corticospinal, anterior corticospinalRubrospinal, reticulospinal, vestibulospinal, tectospinal
Spinal nervesCervicalThoracicLumbarSacralCoccygeal
31 total – formed from the union of dorsal and ventral roots8 pairs12 pairs5 pairs5 pairs1 pair
Dorsal primary rami (mixed sensory and motor)
Innervate dorsal musculature of trunk
Ventral primary rami (mixed)Cervical plexusBrachial plexusLumbosacral plexusPudendal plexus
Innervate ventral musculature of trunk and entire musculature of the extremities (form pluexi)C1-4 – neckC5-8 & T1 – upper extremitiesL1-4 – anterior thigh, L4-5 & S1-3 – post thigh, leg, footS2-4 – pelvic floor
Meningeal branch of spinal nerves
(sensory and vasomotor) – innervate dura mater of cord
Rami communications connect the
Ventral root with the sympathetic trunk
The nuclei of the parasympathetic NS are
Craniosacral
The nuclei of the sympathetic NS are
Thoracicolumbar
The target organs of the parasympathetic NS contain
Muscarinic receptors (ACh)
The target organs of the sympathetic NS contsin
Adrenergic receptors – Muscarinic receptors (sweat glands, adrenal medulla)
Epi and norepi are synthesized from
Tyrosine
Alpha 1 receptors are located on
Vascular smooth muscle (vasoconstriction) and hepatocytes
Alpha 2 receptors are located on
Platelets and white adipocytes (inhibit norepi release)
Beta 1 receptors are located in the
Heart (increase myocardial activity)
Beta 2 receptors are located in the
Lungs, vascular smooth muscle and hepatocytes (arterial vasodilation)
Inhibitory neurotransmitters are
GABA (wide spread) and Glycine (spinal cord, brain stem and retina)
The medulla is part of the myelencephalon which has
Centers to control heartbeat, respiration and blood pressure
The motor decussation is located
Superior to the junction of the medulla with the spinal cord
In the motor decussation
80% of the pyramidal fibers cross
Nucleus gracilus and nucleus cuneatus are located in
The posterior portion of the medulla
After synapsing in nucleus gracilus and cuneatus the pathway continues with
Internal arcuate fibers crossing and ascending as the medial lemniscus
The medial lemniscus pass to the
Cerebellum or thalamus – terminate in the VPL
The cuneocerebellar fibers arise form the
Accessory cuneate nucleus – uncrossed fibers – enter the cerebellum via the inferior cerebellar peduncle – info from the upper extremity and neck (equivalent of the posterior spinocerebellar tract from the lower extremities)
The reticular formation is located at the level of the
High medulla
The Raphe nucleus is part of the
Reticular formation – located in the midline of the medulla, pons and midbrain – synthesizes serotonin
In the reticular formation are vital reflex centersCardiac centerVasomotor centerRespiratory centerVomiting, coughing, swallowing
Control heart rateControls blood pressure – diameter of blood vesselsInitiates and regulates breathing
Which cranial nerves originate in the medulla?
IX, X, XI and XII
CN VIII, auditory pathway (cochlear)Only crossed fibers ascend – uncrossed fibers terminate in the reticular formation
-organ of corti transmits to the cochlear nuclei in the medulla – then transmits to the inferior colliculi – then to the medial geniculate nuclei of the thalamus – then to auditory centers in the temporal lobes
Damage to the cochlear nerves causes
Tinnitus
CN VIII (vestibular)
Receptors are the crista in the ampulla of the semicircular canals, crista of the utricle and the crista of the saccule
The vestibular nuclei projects (vestibulospinal)
Crossed and uncrossed fibers that descend in the MLF
Vestibular efferent fibers from the fastigial nucleus of the cerebellum
Exert inhibitory influences and eliminate the effects of motion sickness and nystagmus
Injury to the vestibular branch of CN VIII causes
Vertigo, ataxia and nystagmus
The organs of static equilibrium are located in
The utricle and saccule - stimulus is gravity
The organs of dynamic equilibrium are located in
The cristi ampullaris of the semi circular canals – the stimulus is angular acceleration
Impulses from the cristi travel to the
Vetibular nuclei via the MLF
Right head movement causes a
Right nystagmus – fast to right – slow to left
Which cranial nerves originate from the pons?
V, VI, VII and VIII
Longitudinal bundles of the pons carry
Corticospinal, corticopontine and corticobulbar fibers
Transverse fibers of the pons originate in the
Pontine gray, cross the midline and go to the cerebellum via the middle cerebellar peduncle
The tectum is part of the midbrain and is made of
The roof of the cerebral aqueduct, superior colliculi and inferior colliculi
Midbrain at the level of the inferior colliculusTectumTegmentum
-reflex centers for auditory system- CN IV- lateral lemniscus - Substantia Nigra
The crus cerebri is located Middle 3/5 containsLateral 1/5 containsMedial 3/5 contains
Lateral and ventral to the tegmentumCorticobulbar and corticospinalCorticopontine from parietal, occipital and temporal lobes Frontopontine from frontal lobe
The only nerve that exits the dorsal brain stem is the
Trochlear nerve (CN IV) – totally crosses
The midbrain at the level of the superior colliculus contains the following nuclei…
Red nucleus, EW nucleus, oculomotor complex, Substantia nigra, brachium of the inferior colliculus
Oculomotor complex includesCaudal central nucleusDorsal nucleusIntermediate nucleusVentral nucleusEW nucelus
Innervate levatorInnervate inferior rectusInnervate inferior oblique Innervate medial rectus
The midbrain at the level of the pretectum contains
The direct and consensual pupillary light reflex centers
The light reflex pathway is
ON > optic chiasm > optic tract > Brachium of the superior colliculus > Pretectal nuclei (synapse) > Ipsilateral and contralateral EW nuclei > Ciliary ganglion with inferior division of CN III >Short ciliary nerves >Constrictor muscles of each eye
Dorsal thalamus Anterior nucleusPosterior end has two elevationsLateral geniculateMedial geniculate
Relay center for impulses from the olfactory organVisual relay stationAuditory relay station
Hypothalamus – floor of the 3rd ventricle
Regulation of body temp, regulation of fat, water and CHO metabolism, sleep, sex and emotions also influenced
Epithalamus – root of the 3rd ventricle contains
Vascular structure – choroids plexus – forms CSF
Subthalamus - relay of sensory info to
Cortex concerning vision, audition and aquilibrium
The internal gray matter of the cerebrum is called the
Basal Ganglia
Brodmann area 4
Frontal lobe – pre central gyrus – motor
Brodmann area 1-3
Parietal lobe – post central gyrus – general sensation
Brodmann area 17
Occipital lobe – visual area
The long parallel folds of the cerebellum are called
Rolla cerebelli
The cerebellar cortex consists of
Purkinje cells
Nuclei of the cerebellumDentate nucleusEmboliform nucleusGlobose nucleusFastigial nucelus
Largest Lies near the midline of the4th ventricle
The inferior cerebellar peduncle carries connections
To and from the medulla oblongata and spinal cord
The middle cerbellar peduncle carries connections
To cerebellum from the pons
The superior cerebellar peduncle carries impulses
From the dentate nucleus to the midbrain
The maintenance of equilibrium involves the
Flocculonodular lobe of the cerebellum
The internal carotid artery enters the skull through the
Carotid canal in the petrous portion of the temporal bone
Two branched of the internal carotid artery are the
Posterior communicating A. and the Ophthalmic A.
At the very end of the ICA it divides into the
Ant. and middle cerebral arteries (part of the Circle of Willis)
The vertebral arteries are the first branches off the…
Subclavian arteries
Vertebral arteries travel in the
Transverse foramina of the upper six cervical vertebra-enter the skull through the foreman magnum
The two vertebral arteries join at the
Posterior rim of the pons – form the Basilar A.
The Basilar A. continues forward and branches at the
Anterior rim of the pons – forms the posterior cerebral As
The circle of Willis includes…
Posterior cerebral As (from Basilar A)Posterior communicating As (from ICA)Anterior cerebral As (from ICA)Anterior communicating A
Vestibuloencephalic pathway functions in
Coordination of eye movements
Vestibulospinal tract functions in the
Coordination of head and body movements
The dorsal and intermediate acoustic striae ascend as
Lateral lemniscus (synapse in contralateral inf. Colliculus)
Somasthetic system
Concerned with bodily sensationsSends info to the postcentral gyrus of each parietal lobe
Limbic system
Concerned with emotion, autonomic activity, motivationHypothalamus, hippocampus and amygdala
Olfactory axons pass through the
Cribriform plate of the ethmoid bone
The area for smell association is located in the
Frontal lobe (gyrus cinguli)
The area for smell appreciation is in the
Temporal lobes (uncus)
The amygdaloid nucleus enables olfactory stimuli to
Influence food seeking and sexual behavior
Taste buds on posterior 1/3 of tongue
CN IX (glossopharyngeal) afferent neurons
Taste bunds on anterior 2/3 of tongue
CN VII (facial) afferent neurons
Lingual branches of nerves synapse in the
Solitary nucleus
Neurons for taste ascend in the
Medial lemniscus > VPL > inf. Postcentral gyrus (parietal)
The predominant synapse in the nervous system is
The chemical synapse
The inverse myotonic reflex involves the
Golgi tendon organ
The flexor withdrawal reflex involves the
Cutaneous receptors
Negative feedback is a
Corrective action to return things to normal
Pacinian corpuscles respond to
Touch (pressure), aka tactile sensation – free nerve endings encapsulated in connective tissue
A dynamic proprioceptor generates an action potential
Only with a change in direction of movement
The basilar membrane in the ear responds to
Different frequencies of sound by changing form
The basilar membrane has microvilli on it called
Hair cells
Movement of the hair cells toward the kinocillium
Results in depolarization/ activation
Movement of the hair cells away from the kinocilium
Results in inhibition/ hyperpolarization
Statokinetic reflexes aka righting reflexes
Restore normal orientation of head and body in space
Static reflexes depend on
Labyrinth organs, proprioceptors in the neck muscles, visual input and input from muscles of the trunk and limbs
Muscle spindles (stretch receptor) sense the
Length of the muscle and its velocity of contraction
Nuclear bag fibers are innervated by
Type 1a nerve fibers – info about muscle length and velocity
Nuclear chain fibers are innervated by
Type II nerve fibers – info about muscle length
Gamma motor neurons
Regulate the sensitivity of Type 1a fibers
Crossed corticospinal fibers form the
Lateral corticospinal tract – innervate distal muscles
Uncrossed corticospinal fibers form the
Ventral corticospinal tract – innervate axial muscles
The basal ganglia are involved with the control of
Mvmt that requires constant monitoring by sensory feedback
The cerebellum has 3 basic function
-planning of a movement-control of posture and equilibrium-control of limb movement
The basal ganglia include
Caudate nucleus and lentiform nucleus (putamen and globus pallidus)
Caudate and the putamen receive
Input to the basal ganglia
The globus pallidus provides
Output from the basal ganglia
Caudate and the putamen regulate
Unconscious contractions (arm swinging while walking)
Globus pallidus regulates
Muscle tone for specific intentional body movements
Vestibulospinal tract
Reflex control of equilibrium
Tectospinal tract
Coordination of headand body movements in response to visual, auditory and cutaneous stimuli
Reticulospinal tract
Maintain posture and control of sweat gland activity
Lateral reticulospinal tract
Innervate flexors in the control of posture
Rubrospinal tract
Control of distal flexor muscles
All preganglionic neurons are
Cholinergic (parasympathetic and sympathetic) nicotinic
Parasympathetic postganglionic neurons are
Cholinergic
Sympathetic posteganglionic neurons are
Mostly adrenergic