Asc and Desc Tracts Flashcards
What kind of information does the asc pathway carry and from where to where
It carries sensory information from body to brain
What kind of information does the desc pathway carry and from where to where
It carries with motor information from brain to muscles / glands
In the asc pathway, where do the impulses come from?
Are they cortico or spino
Comes from pain, thermal, tactile, muscle and joint receptors
Spino
Is the desc pathway cortico or spino
Cortico
What is contralateral decussation
Pathways cross to the opposite side
What is ipsilateral decussation
Pathways ascend on the same side
How many sensory neurons are involved in the asc pathway
3 ( Primary, Secondary, Tertiary )
How many neurons are involved in the motor pathways
Upper Motor Neuron
Lower Motor Neuron
Sensory pathways are ascending pathways that conduct information about ( 5 )
Limb position Sensations of Touch Temperature Pressure Pain ...... to the brain
What are the three types of somatosensory pathways
Posterior column - medial lemniscus
Spinothalamic
Spinocerebellar
There are two kinds of corticospinal tracts. What are they and what kind of information do they carry
Lateral Corticospinal Tract
Anterior Corticospinal Tract
They conduct motor information
Wheat fascicles are present in Post Column - Medial Lemniscus ( 2 )
Fasciculus Gracilis
Fasciculus Cuneatus
Were do you find the fasciculus gracilis ( in terms of SC )
Present throughout cord length ( Sacral, Lumbar, and lower 6 Thoracic spinal Nerves )
Where do you find fasciculus cuneatus
Present in T6 and cervical cord segments
What are the tracts collectively called in the spinal cord
Posterior Funiculus
What are the tracts within the brainstem called
Medial Lemniscus
Describe the pathway of Posterior Column Medial Lemniscus Pathway
1) Fibers will ascend ipsilaterally
2) They synapse w neurons in the gracile and cuneate nucleus of the medulla
3) Sensory decussation of second order neurons occur in the medulla oblongata.
3) Medial Lemniscus ascends to pons, midbrain and synapse at VPL of thalamus
What is composed of the Spinothalamic Pathway ( 2 )
Where is the anterior and lateral white funiculi of SC located ?
Anterior and Lateral Spinothalamic Tract
Located in the whit funiculi of spinal cord, anteriorly and laterally
What kind of stimuli does the
1) Anterior
2) Lateral
Spinothalamic tracts carry
1) Light / Crude touch and pressure
2) Pain and Temperature
Describe the pathway of spinothalamic pathway
1) Primary neuron synapses w cells of posterior gray matter
2) Secondary neurons decussate in the spinal cord before ascending the brainstem
3) Synapses w third order neurons in VPL nucleus of thalamus
What kind of information does the spinocerebellar pathway conduct ?
Proprioceptive information to the cerebellum as it helps coordinate body movement
Describe the pathway of the spinocerebellar pathway
1) Axons enter the posterior tray column and synapses with the secondary neuron
2) Axons ascend ipsilaterally to the medulla
What do the motor pathways do
It regulates skeletal muscle activity
Where is the upper motor neuron found?
Located in the cerebral cortex or a nucleus within the brainstem
Where is the lower motor neuron found?
Located either within anterior grey matter of spinal cord
Or within brainstem cranial nerve nucleus
Where does the corticospinal tract ( pyramidal pathway ) originate
Originates in the cerebral cortex
Where do the axons descend through ?
Descends through the internal capsule, enters cerebral peduncles forming descending motor tracts and will form thick anterior bulges in medulla oblongata called pyramids
Where does synapse occur in the corticospinal tract
Synapses in the anterior grey matter of the spinal cord
Where does the lateral corticospinal tract decussate and what do the axons of LMN innervate
It decussates within the pyramids of the medulla oblongata
Axons innervate the skeletal muscles that control skilled movements
Where does decussation occur in the anterior corticospinal tracts
Decussates with interneurons or lower motor neurons in the anterior grey matter of SC
What does the LMN of the anterior corticospinal tracts innervate
It innervates the axial skeletal muscle
