Ascending and descending tracts Flashcards
What are the two types of ascending tract?
Conscious and unconscious
What are the different conscious ascending tracts?
Dorsal column medial leminscal pathway and anterolateral system
What is the 1st order neurone of the DCML from the upper limb?
Sensation of the upper limb travels in the fasciculus cuneatus (lateral part of the dorsal column) and synapse in the nucleus cuneatus of the medulla.
What is the 1st order neurone of the DCML from the lower limb?
Sensation from the lower limb travels in the fasciculus gracilis (medial part of the dorsal column) and synapse in the nucleus gracalis of the medulla
What is the 2nd order neuron of the DCML?
Begins in the nucleus (either gracalis or cuneautus), ad then decusates in the medulla. This then travels in the contralateral medial lemiscus to the thalamus
What is the 3rd order neuron of the DCML?
Begins in the thalamus and then travels through the internal capsule to terminate at the sensory cortex
What sensations are carried in the DCML?
Sensory modalities of fine touch, vibration and proprioception from either the upper or lower limb
What sensations are carried in the anterior spinothalamic tract?
Sensory modalities of crude touch and pressure from both the upper and lower limb
What sensations are carried in the lateral spinothalamic tract?
Sensory modalities of pain and temperature from both the upper and lower limb
What is the first order neuron of the anterolateral system?
Arise from sensory receptors in the periphery of both the upper and lower limb. They enter the spinal cord, ascend 1-2 spinal levels, then synapse at teh tip of the dorsal horn
What is the second order neuron of the anterolateral system?
Begin at the tip of the dorsal horn, then decussate within the spinal cord, forming two seperate tracts which then travel together to the thalamus.
What is the third order neuron of the anterolateral system?
Travels from the thalamus to the ipsilateral primary sensory cortex of the brain through the internal capsule
What information does the posterior spinocerebellar tract carry?
Proprioceptive information from lower limbs to the ipsilateral cerebellum
What information does the cuneocerebellar tract carry?
Proprioceptive information from the upper limbs to the ipsilateral cerebellum
What information does the anterior spinocerebellar tract carry?
Proprioceptive information from the lower limbs, and decussate twice so travel to the ipsilateral cerebellum
What information does the rostral spinocerebellar tract carry?
Proprioceptive information from the upper limbs to the ipsilateral cerebellum
What are the 4 spinocerebellar tracts?
Posterior spinocerebellar tract
Cuneocerebellar tract
Anterior spinocerebellar tract
Rostral spinocerebellar tract
What information does the spinoreticular tract carry?
Deep/chronic pain
What are the two major groups of descending motor pathways?
Pyramidal and extrapyramidal tracts
Where do the pyramidal tracts originate?
Precentral gyrus
What information does the pyramidal tracts carry?
Voluntary control of musculature of the body and face
What are the different pyramidal tracts?
Corticospinal and corticobulbar
What is the UMN of the corticospinal tract?
Originates in the precentral gyrus as corona radiata. These converge and run through the internal capsule, through the crus cerebri, pons and into the medulla. Then divide into the lateral and anterior corticospinal tracts.
What is the route of the lateral corticospinal tract after its division at the medulla?
Decussates at the medulla and then descends into the spinal cords. Terminates on the ventral horn
What is the route of the anterior corticospinal tract after its division at the medulla?
Decussates at the medulla and then remains ipsilateral. Terminates at the ventral horn of the cervical and upper thoracic segments
What percentage of the corticospinal tract is the lateral?
90% (10% is anterior)
What information does the lateral corticospinal tract carry?
Muscular movement to the limbs
What information does the anterior corticospinal tract carry?
Muscular movements to the axial muscles
What information does the corticobulbar tract carry?
Musculature of the head and neck
What is the UMN of the corticobulbar tract?
Travels from the primary motor cortex through the internal capsule then terminates at the brainstem on the nuclei of the cranial nerves
What is the LMN of the corticobulbar tract?
Motor signals from the cranial nerve nuclei to the muscles of the face and neck
Are the extrapyramidal tracts conscious or unconscious?
Unconscious
Where do extrapyramidal tracts originate?
Brainstem
What information do the extrapyramidal tracts carry?
Involuntary and automatic control of all musculature, such as muscle tone, balence, posture and locomotion
What are the 4 extrapyramidal tracts?
Tectospinal, rubrospinal, vestobulospinal, reticulospinal
Where does the tectospinal tract originate?
Superior colliculus
What information does the tectospinal tract carry?
Head turning in response to visual stimuli
Where does the rubrospinal tract originate?
Red nucleus
What information does the rubrospinal tract carry?
Limb flexors, fine hand control
Which extrapyramidal tracts decussate?
Tectospinal and rubrospinal
Where does the vestibulospinal tract originate?
Vestibular nuclei
What information does the vestibulospinal tract carry?
Posture and balence
Where does the reticulospinal tract originate?
Reticular formation
What information does the reticulospinal tract carry?
Spinal reflexes, posture
Will there be wasting (atrophy) in a UMN or a LMN lesion?
LMN
What will happen to muscle tone in an UMN and a LMN lesion?
UMN- Hypertonia
LMN- Hypotonia
What will happen to reflexes in an UMN and a LMN lesion?
UMN- Hyperreflexia
LMN- Hyporeflexia
