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Spinal Cord III
N/A
62
Anatomy
Graduate
01/14/2012

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Cards

Term
Ascending tracts carry information between what structures and in what direction?
Definition
Spinal cord to the brainstem
Term

Descending tracts carry information between what structures and in what direction?

Definition
Forebrain and brainstem to the spinal cord
Term
What is formed by propriospinal axons?
Definition
Local circuitry of the spinal cord such as intersegmental reflexes
Term
Long tracts are generally defined as tracts that carry information between what structures?
Definition
Spinal cord and the cerebrum or brainstem
Term
What are the primary spinal cord long tracts?
Definition
Corticospinal, posterior (dorsal) column-medial lemniscal system, anterolateral system, spinocerebellar tracts, hypothalamospinal system
Term
The corticospinal tract is part of the pyramidal system and is associated with what type nervous system control?
Definition
Volitional motor
Term
The posterior (dorsal) columm-medial lemniscal system is associated with what nervous system responses?
Definition
Descriminative touch, vibration, proprioception
Term
The anterolateral systen is a spinal cord long tract used to carry what type of sensory information?
Definition
Pain, temperature, crude (protopathic) touch
Term
What kind of sensory information do spinocerebellar tracts convey to the cerebellum?
Definition
Unconscious proprioception from muscles via muscle spindles and golgi tendon organs
Term
The hypothalamospinal system is the central control of what types of neurons in the spinal cord?
Definition
Preganglionic autonomic
Term
The major source of volitional motor control comes from what system?
Definition
Pyramidal system
Term
Neurons of the pyramidal system originate from where?
Definition
Cerebral cortex
Term
The pyramidal system sends projections to what parts of the CNS?
Definition
Brainstem and spinal cord
Term
Cortical neurons of the pyramidal tract are called what?
Definition
Upper motor neurons
Term
How are spinal cord and brainstem motor neurons that directly innervate muscle labeled?
Definition
Lower motor neurons
Term
What component of the pyramidal system projects into the spinal cord?
Definition
Corticospinal tract
Term
Where do axons of the corticospinal tract originate?
Definition
2/3 from the neurons in the motor cortex and 1/3 from sensory areas
Term
The overwhelming majority of corticospinal axons cross the midline at the level of the foramen magnum to descend in what?
Definition
Dorsal part of the lateral funiculus on the contralateral side
Term
An injury to the motor area of the brain on one side produces motor deficits on which side of the body?
Definition
Contralateral
Term
The small amount of pyramidal axons that do not cross the midline after entering the foramen magnum form what?
Definition
Anterior corticospinal tract
Term
Axons of the corticospinal tract partially cross the midline at the spinal level at which they innervate motor neurons and interneurons associated with what structures?
Definition
Axial musculature
Term
Are corticospinal axons exitatory or inhibitory to flexors?
Definition
Exitatory
Term

Are corticospinal axons exitatory or inhibitory to extensors?

Definition
Inhibitory
Term
Corticospinal tract innervation is meant to control what types of movements in the extremities?
Definition
Fine skilled movements
Term
What other descending tracts apart from the corticospinal tract contribute to normal motor function?
Definition
Rubrospinal, vestibulospina, and reticulospinal pathways
Term
What is the other flexor biased tract alongside the corticospinal tract?
Definition
Rubrospinal tract
Term
Where does the rubrospinal tract originate?
Definition
Red nucleus of the rostral midbrain, crosses the midline near its origin
Term
The primary function of the rubrospinal tract is to provide innervation for flexors in what part of the body?
Definition
Arm and forearm
Term
What are the extensor biased descending tracts?
Definition
Vestibulospinal and reticulospinal tracts
Term
The vestibulospinal and reticulospinal tracts have major effects on what type of extensor muscles?
Definition
Postural muscles related to balance and proximal body muscle tone
Term
Reticulospinal tracts originate froom nuclei in the brainstem reticular formation and travel in the ventral and ventral lateral funiculus in order to influence primary motor neurons supplying what muscles?
Definition
Paraverterbal and limb extensors involved in muscle tone and posture
Term
The two primary vestibulospinal tracts given off by vestibular nuclei that receive input of the vestibular portion of the vestibulocochlear nerve help innervate muscles that perform what actions?
Definition
Extensors invovled with body posture and orientation
Term
Vestibular nuclei that give rise to the vestibulospinal tracts reveive direct input from what part of the brain?
Definition
Vestibular apparatus and the cerebellum
Term
What systems constitute the upper motor neuron influences for visceromotor activity?
Definition
Mostly hypothalamus, some brainstem
Term
Upper motor neurons that influence the visceromotor activity primarily target what neurons?
Definition
Preganglionic autonomic neurons of the intermediolateral cell column
Term
What is the major pathway of the upper motor neurons that influence visceromotor activity via preganglionic neurons in the spinal cord?
Definition
Hypothalamospinal tract
Term
What are the ascending tracts in the spinal cord?
Definition
Dorsal columns, anterolateral system, and spinocerebellar tracts
Term
The dorsal columns are composed primarily by what structures?
Definition
Central processes of dorasl root ganglion neurons
Term
What kind of sensory input is carried by the dorsal columns?
Definition
Discriminative touch, vibration, position sense, and kinesthesis
Term
The dorsal column information is carried ipsilaterally in the spinal cord via what subdivisions?
Definition
Fasciculus gracilis (positioned medially) and fasciculus cuneatus (positioned laterally)
Term
What separates the fasciculus gracilis and fasciculus cuneatus of the dorsal column?
Definition
Posterior intermediate sulcus
Term
The fasciculus gracilis consists of axons of dorsal root ganglion neurons at what verterbral level?
Definition
Below T6
Term
Fasciculus cuneatus contains axons of dorsal root ganglion at what verterbal level?
Definition
Above T6
Term
How are axons in the dorsal columns organized?
Definition
Somatotopically (medial to lateral orientation: foot/leg -> trunk -> arm/neck)
Term
Where do dorsal column axons synapse?
Definition
Nucleus gracilis cuneatus
Term
What tract is formed by axons from the nucleus gracilis and cuneatus?
Definition
Medial lemniscus
Term
At what level do axons from the nucleus gracilis and nucleus cuneatus cross the midline to form the medial meniscus?
Definition
Medulla
Term
The medial lemniscus travels from its origin in the medulla to what part of the brainstem?
Definition
Thalamus which then project to sensory areas of the cerebral cortex
Term
The anterolateral system is a collection of tracts tha carries what type of sensation?
Definition
Protopathic (pain, temperature, crude touch)
Term
Where does the anterolateral system enter the spinal cord?
Definition
Lateral division of the dorsal root entry point
Term
Along which funiculi do tracts of the anterolateral system travel?
Definition
Lateral, partly anterior
Term
Within which lamina of the dorsal horn do axons contributing to the anterolateral system synapse?
Definition
Lamina I-V
Term
On which side of the spinal cord do axons form the atnerolateral system?
Definition
Opposite the point of entry
Term
What are the two routes the anterolateral system uses to reach the somatosensory cortex?
Definition
Spinothalamic tracts to the thalamus (direct route) or reticular formation collaterals via spinoreticular fibers (indirect)
Term
Why are sensations carried by the anterolateral system resistant to disruptions by localized lesions?
Definition
Collaterals of anterolateral system axons are given off to some local areas of the spinal cord, providing several pathways to the cerebral cortex
Term
Spinocerebellar tracts carry unconscious sensation from what types of receptors found primarily in muscles and joints?
Definition
Muscle spindles, joint capsules, skin
Term
Spinocerebellar convey information to the cerebellum to help perform what kinds of tasks?
Definition
Coordinate muscle activity
Term
Spinocerebellat tracts send sensory information through the dorsal root ganglia to cells within what part of the spinal cord?
Definition
Intermediate zone of the spinal grey matter
Term
The spinocerebellar tract is divided into anterior, posterior, and cuneocerebellar tracts. What part of the body sends sensory information to the anterior and posterior divisions of the spinocerebellar tract?
Definition
Lower limb
Term

The spinocerebellar tract is divided into anterior, posterior, and cuneocerebellar tracts. What part of the body sends sensory information to the cuneocerebellar division of the spinocerebellar tract?

Definition
Upper limb
Term
Do the spinocerebellar tracts ascend the spinal cord ipsalaterally or contralaterally?
Definition
Ipsilaterally for posterior and spinocerebellar, contralaterally for anterior
Term
What supplies blood to the dorsal columns?
Definition
Posterior spinal artery
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