Somatomotor Pathways Flashcards
(22 cards)
Upper motor neurons are located in _____ and are referred to as ____ cells.
They synapse with LMN located in ______ or ______ and are considered part if the ____.
Damage to UMN results in _____ because ______.
Primary motor cortex
Pyramidal
Cranial nerve nuclei
Anterior grey horn of spinal cord
CNS
Spastic paralysis
UMN are largely inhibitory to LMN and therefore result in LMN over activity (LMN always excitatory)
Where are LMN cell bodies located
Cranial nerve nuclei
Anterior grey horn
Damage to LMN causes ______
Flaccid paralysis
Amyotrophic lateral sclerosis (ALS) shows both ____ and LMN signs because it targets motor cells in the _____ of the spinal cord and the ______/______ tracts
UMN
Anterior grey horn (LMN)
Corticospinal/ bulbar
Two types of motor neurons =
Alpha motoneurons target—> (LMN ie: extrafusal fibers)
Gamma motoneurons target—> (intrafusal fibers ie: Muscle spindle cells)
The major control region of direct and some indirect motor pathways is
Primary motor area of cerebral cortex
Basal ganglia control
Muscle tone
Starting and stopping movements
Integration of: semi-voluntary, automatic, stereotyped mvmts
Cerebellum provides _______ and fine tunes
Internal feedback
Motor commands
The reticular formation gives rise to ____ which coordinates mvmt of ________
Reticulospinal tracts
The trunk and proximal limbs
The ________ of the pons gives rise to which indirect pathway responsible for balance
Vestibular nucleus (CN VIII) Vestibulospinal tract
The _______ nucleus in the ______ is the origin of the rubrospinal tract which functions to control movements of _______.
Red
Midbrain
Hands and feet (coordination of)
Coordination of the eyes and head in response to stimuli comes from the ______ tract which originates in the _____ of the _____.
Tectospinal
Superior and inferior colliculi (tectum)
Midbrain
Explain the breakdown of fibers in the corticospinal tracts
1/3 primary motor cortex (umn)
1/3 premotor fibers
1/3 post central gyrus (sensory) sensation that accompanies movement pattern (engram?)
Two major differences between anterior and lateral corticospinal tracts:
1- lateral serves feet and hands (skilled mvmt of)
Anterior serves axial skeleton (neck/trunk)
2- lateral decussates in medulla at pyramids
Anterior decussates in spinal cord at level of exit
90% of the fibers in the corticospinal tract are ______ while the other 10% are and are important during _____.
Lateral corticospinal fibers
Anterior corticospinal fibers
Spinal rehabilitation. (Relearning mvmts)
Direct pathways include
Corticobulbar tracts
Anterior corticospinal
Lateral corticospinal
Which cranial nerves are excluded from Corticobulbar tracts
Vestibulocochlear (CNVIII)
Olfactory (CN I)
Optic (CN II)
Corticobulbar tracts innervates structures ______ that is each nerve has two branches (one stays ipsilateral while one ______)
The LMN of these tracts originate in _______ of the ____ and exit the brain without descending the cord.
Bilaterally
Decussates
Cranial nerve nuclei
Brainstem
UMN of indirect pathways originate in the ______ and synapse with ______or _______.
Brain stem
LMN
Association neurons (interneurons)
5 indirect pathways are :
Rubrospinal Medial Reticulospinal Lateral Reticulospinal Tectospinal Vestibulospinal
Superior colliculus of the _______ tract responds to ______ stimuli while the inferior colliculus responds to ______.
UMN of this tract originate in the ______ and control _______&______ mvmt in response to stimuli.
Tectospinal Visual Auditory Midbrain Head and eye
_______ originates in the reticular formation of the _____. The medial tract is excitatory to _______ while the lateral is excitatory to ____(inhibit each other)
This tract maintains __________ and facilitates smooth motions via medial and lateral divisions
Reticulospinal
Medulla
Extensors
Flexors
Upright posture
