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36 Cards in this Set

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foramen magnum
Large opening at the base of the occipital bone through which the medulla is continuous with the spinal cord.
conus medullaris
The conical-shaped caudal end of the spinal cord; located at the caudal edge of vertebra at L1 or rostral edge of L2.
filum terminale externum
Caudal thin extension of the spinal dura that surrounds the filum terminale internum; also known as the coccygeal ligament.
cauda equina
Consists of a bundle of nerve roots of all the spinal nerves caudal to the second lumbar vertebra.
cervical enlargement
Includes four lower cervical segments and the first thoracic segment. The nerves emerging from this enlargement for the brachial plexus.
lumbar plexus
nerve roots from L1- L4. Innervate the lower extremities
sacral plexus
nerve roots from L4- S2. Contain parasympathic fibers and motor fibers innervating the bladder and its sphincters respectively
funiculus
A bundle containing one or more tracts or fasciculi in the spinal cord.
lateral funiculus
White matter of the lateral aspect of spinal cord; contains both ascending (spinothalamic, spinocerebellar) and descending (corticospinal, rubrospinal) fibers.
dorsal (posterior) funiculus
Is located between the dorsal horn and a midline structure called the dorsal (posterior) median septum. Consists of the fascuculi gracilis and cuneatous.
anterior (ventral) funiculus
Located between the anterior (ventral) median fissure and the site where the ventral root exits.
gray commissure
A band of gray matter extending onto both sides of the spinal cord.
anterior (ventral) white commissure
Located ventral to the gray commissure; consists of decussating axons.
central canal
Extends throughout the spinal cord; in the adult, it is patent only in the upper cervical segments. Located in the gray commisure.
zone of Lissauer (Lissauer's tract)
(dorsolateral tract or fasciculus) Refers to the tract formed by central axons of sensory neurons mediating pain that branch into ascending and descending collaterals.
substantia gelatinosa
Region of gray matter of the dorsal horn of spinal cord that receives mainly pain and temperature inputs from the periphery.
dorsal nucleus of Clarke (Nucleus Dorsalis of Clarke)
Group of large neurons located at the base of the dorsal horn in all thoracic spinal segments C8–L3; receives muscle spindle and tendon afferents predominantly from the caudal aspect of the body and lower limbs; gives rise to dorsal spinocerebellar tract, which terminates in ipsilateral cerebellum.
intermediolateral cell column (IML)
Lateral extension of spinal gray matter (lateral horn); present in thoracic (T1–L2) and sacral (S2–S4) cord; thoracic IML contains preganglionic sympathetic neurons; sacral IML contains parasympathetic preganglionic neurons.
fasciculus cuneatus
First-order sensory neurons contained in the dorsal funiculus that project to the nucleus cuneatus and that convey the modalities of conscious proprioception and tactile sensation from the ipsilateral side of the upper limb. T6 and above
fasciculus gracilis
First-order sensory neurons contained in the dorsal funiculus that project to the nucleus gracilis and that convey the modalities of conscious proprioception and tactile sensation from the ipsilateral side of the lower limb. T-7 and below
nucleus gracilis
Second-order neurons located in the lower medulla that receive conscious proprioceptive and tactile inputs from the fasciculus gracilis; projects through the medial lemniscus to the ventral posterolateral nucleus of thalamus, conveying information from the lower limb.
internal arcuate fibers
Fibers arising from dorsal column nuclei that pass ventrally for a short distance in an arc-like trajectory before crossing over to the contralateral side as the medial lemniscus.
medial lemniscus
Major ascending sensory pathway arising from the nucleus gracilis and nucleus cuneatus, mediating conscious proprioception and tactile sensations from the limbs to the contralateral ventral posterolateral thalamic nucleus
ventral posterolateral nucleus
Nucleus situated in the ventrolateral aspect of the posterior thalamus; receives inputs from the medial lemniscus and spinothalamic tract and projects to the postcentral gyrus.
nucleus cuneatus
Second-order neurons located in the lower medulla that receive conscious proprioceptive and tactile inputs from the fasciculus cuneatus; projects through the medial lemniscus to the ventral posterolateral nucleus of thalamus, conveying information from the upper limb.
Fasciculus Gracilis and Cuneatous (Dorsal Column)
Crosses at decussation medial lemniscus; terminates in sensorimotor cortex; symptoms appear ipsilateral; include loss of tactile sense (vibration, deep touch, and two point discrimination) and kinesthetic touch (position and movement)
Dorsal (Posterior) Spinocerebellar Tract (DCST)
The central processes project to the nucleus dorsalis of Clarke the extends from C8 to L2 (ascend ipsilaterally), reach the inferior cerebellar peduncle in the medulla, and terminate ipsilaterally in the cerebellar vermis; transmits information about muscle spindle and tendon afferents from caudal aspect of the body and legs; coordinates and integrates nerural signals of individual lower limb muscles.
Ventral (Anterior) Spinocerebellar Tract
Crosses first in the spinal cord and crosses again in superior cerebellar peduncle and terminates in vermal region of the anterior lobe of the cerebellum; involved in attempted movement
Cuneocerebellar Tract
Only in C1- C7; Ascends ipsilaterally in the fasiculus cuneatus; and project to neurons located in the accessory cuneate nucleus; goes through cerebellar peduncle and terminates in cerebellar cortex; convery unconscious proprioception
Lateral spinothalmic tract (ALS)
Arises form nucleus proprius; cross via the ventral (anterior) white commissure where the ascend in the lateral funiculus; axons synapes in the ventral posterolateral nucleus of the thalmus and project into the primary sensory cortex; mediates pain, temperature and simple tactile sensations
nucleus proprius
Located in the dorsal horn; neurons of this nucleus give rise to the spinothalamic tract.
cortiocspinal tract
Arises from the motor cortex (homunculus), passes through the pyramaids and crosses at the decussation of the pyramaids (the majority do) to form lateral spinal tract
Brown-Sequard Syndrome
Loss of conscious proprioception and two-point discrimination occurs below the level of the lesion on the ipsilateral side, and loss of pain and temperature sensation occurs one or two segments below the level of the lesion on the contralateral side as well as bilaterally. There is also an upper motor neuron paralysis below the level of the lesion on the ipsilateral side and a lower motor neuron paralysis at the level of the lesion on the ipsilateral side. This kind of incomplete transection may occur by fracture dislocation of vertebrae, tumor, or missile wounds.
Myotatic Reflex (Stretch, Deep Tendon, or Two Neuron Reflex)
pg 157
Flexion (Withdrawal) Reflex
When a noxious stimulus is applied to the skin or deeper structures, free nerve endings are stimulated, and the resulting impulses are conducted through myelinated afferent fibers of small diameter (group III fibers) and unmyelinated afferent fibers. These fibers synapse with a number of alpha motor neurons located in the spinal cord. These connections are polysynaptic, and at least three to four interneurons are involved. Activation of these polysynaptic pathways in the spinal cord results in contraction of ipsilateral flexor muscles, producing flexion and relaxation of ipsilateral antagonist extensor muscles.
Crossed Extension Reflex
This neuronal circuitry of the flexion and crossed extension reflexes permits extension of the limb contralateral to the site of noxious stimulation and withdrawal (flexion) of the limb ipsilateral to it. Crosses anterior commissure.