Ascending And Descending Tracts Flashcards
Where do tracts of the conscious pathway go
Pass through thalamus and get to Cerebral cortex
What are the ascending tracts
Lateral spinothalamic tract Ventral spinothalamic tract Posterior column Dorsal spinocerebellar Ventral spinocerebellar Spinoolivary
Function of dorsal column
Conscious propioception like discriminatory touch ,vibration ,form recognition ,joints and muscles sensation
Inputs of posterior column
Input : pacini and meissner corpuscle , joint receptos, mucle spindles, golgi tendon organ
Where is the first order neuron of the posterior column located
In the dorsal root ganglion at all levels
\ Where do ascending fibers of posterior column travel
Fasciculus in gracilis and fasciculus cuneatus
Where do you find fasciculus a gracilis in the spinal cord
In the lumbar and sacral region
Where do you find fasciculus cuneatus in the spinal cord
In upper thoracic and cervical
Where are located the second order you one of the posterior column
In the gracile and cuneate nuclei of caudal medulla
What fiber is formed by gracile and cuneate nuclei
Internal Arcuate fibers
At which level does the posterior column decussate
In the medulla when internal arcuate fiber is formed
What structure is formed after decussation of the internal arcuate fiber
Medial lemniscus
Where does the medial leminscus ascends in the brainstem and where does it terminate
Contralateral brainstem and terminate in ventral posterolateral nucleus of thalamus
Where are the third order neurons of the dorsal column located
In the ventroposterolateral nucleus of thalamus
Where do the third order neurons of the posterior column project to
To the postcentral gyrus
Function of posterior spinocerebellar tract
Unconscious propioception of muscle joint sense and pressure
Where is the second order neuron of posterior spinocerebellar tract located
Nucleus dorsalis of clarke from t1 to l3
Does the posterior spinocerebellar tract cross
no
From where does the posterior spinocerebellar tract enter the cerebellum
Through inferior peduncl
Function of ventral spinocerebellar tracts
Unconscious propioception to cerebellum from trunk upper and lower limbs
Where do the first order nucleus of the ventral spinocerebellar tract end
Nucleus dorsalis
Are second order neurons of the ventral spinocerebellar tract crossed
Yes
From where do the central spinocerebellar tract neuron enter the cerebellum
Superior cerebellar peduncl
Function of lateral spinothalamic tract
Mediate pain and temperature
Where are the first order neuron of the lateral spinothalamic tract located
In the dorsal root ganglion
Tract formed when ascending branhch of lateral spinothalamic forned
Posterolateral tract of lissauer
Is the Lateral spinothalamic tract crossed and conscious
Yes
Where do the second order neurons of the lateral spinothalamic tract end
Contralateral thalamus
What is the function of the anterior spinothalamic tract
Light touch
pressure
Where are the first order neuron of the anterior spinothalamic tract located
Dorsal root ganglion
Where are the second order neuron of the anterior spinal ceramic tract located
Posterior grey horn in substantia gelatinosa where they cross
Where do the second or the neuron of the anterior spinothalamic tract end
The ventral posterolateral tract of thalamus via posteiror limb of internal capsule and corona radiata
What are lower motor neuron
Neurons of the interior gray horn of the spinal cord that innervate skeletal muscle
What are the upper motor neuron
Urine from Supraspinal areas that are descending tracts
What are the major descending pathways
Lateral corticospinal tract ventral corticospinal tract rubrospinal tract tectospinal tract Vestibulospinal tract reticulospinal tract Autonomic
Function of corticospinal tract
Voluntary discrete skilled movement
Function of Reticulospinal tract
Facilitate or inhibits voluntary movement or reflex activity
Tectospinal tract function
Reflex postural movements in response to visual stimuli
Rubrospinal tract function
Facilitate activity of flexor muscles and inhibits extensor muscle
Vestibular spinal tract function
Inhibit flexor muscle
Facilitate extensor muscle
Autonomy function
Visceral activity
What are the tract part of the Piramidal system
Corticospinal tract
Where do the fibers of the corticospinal tract originate from in the cortex
2/3 originate from precentral gyrus 1/3 originate from postcentral gyrus
Number of axons per pyramids cells
About 1 million
Percentage of myelinated axons in corticospinl meduulla
70
75 to 90% of fibers of corticospinal tract decussate at spinomedullary junction and form
Lateral corticospinal tract
Origin of rubrospinal tract
Red nucleus in midbrain
Does the rubrospinal tract cross
Yes
Origin of tectospinal tract
Superior colliculus of midbrain
Where does the tectospinal tract cross
In the periaquaductal grey
What happens if there’s acute lesions to the upper motor neuron
Transient spinal shock with flaccid paralysis, areflexa ,hypotonia
What happens if there’s chronic lesions to the upper motor neuron
Spastic paralysis hypertonia reduction or loss of superficial abdominal and cremasteric reflex extensor toe response (babinski sign) Clonus
Consequences of lesion to lower motor neuron
Flaccid paralysis areflexia Muscle atrophy Fasciculation Fibrilliatio
