Motor system

class 8

Motor planning: Premotor cortex does what?

plans, organizes and coordinates groups of muscles to work together; plans how to move based on sensory feedback; sequencing

Motor planning: Supplementary motor cortex does what?

movement coordination particularly both sides of the body

Primary motor cortex does what? Where is it located?

carries out the complex movements and is located in the posterior region of the frontal lobe within the precentral gyrus

Motor system parts: cerebellum does what?

provides for smooth, coordinated movements by processing info from the motor cortex, proprioception, and other sensory inputs

Motor system parts: Basal Nuclei (a.k.a. basal ganglia) does what?

can influence motor movements made by the primary motor cortex: also, help start, stop, and control intensity of movements; helps influence balance and gait

Descending motor tracts: Postural/gross movement tracts does what?

Controls skeletal muscle activity (unconscious or involuntary)

Descending motor tracts: Fine movement and limb flexion tracts does what

Controls limb and face movements.

Descending motor tracts: Nonspecific UMN tracts:

Facilitates all LMNs

Alpha motor neurons (LMN) characteristics?

have large cell bodies and large myelinated axons. Axons of alpha motor neurons project to extrafusal skeletal muscle.

Gamma Motor Neurons (LMN) characteristics?

have medium-sized myelinated axons. Axons of gamma motor neurons project to intrafusal fibers in the muscle spindle.

UMN’s are classified into three types, what are those called?

Medially, laterally, or through ventral horn.

Tectospinal tract: Origin?

Tectum posterior midbrain

Tectospinal tract: Descending pattern?

Ipsilateral

Tectospinal tract: Region of synapse?

Cervical

Tectospinal tract: Functions?

Stimulates muscles and coordinates head and neck movement. Also turns to visual and auditory stimuli

Medial vestibulospinal tract: Origin?

Medial vestibular nucleus of upper medulla

Medial vestibulospinal tract: descending pattern?

bilateral

Medial vestibulospinal tract: region of synapse

Cervical/lumbar

Medial vestibulospinal tract: functions?

Helps maintain balance while standing or moving

Lateral vestibulospinal tract: Origin?

Lateral vestibulospinal nucleus of upper medulla

Lateral vestibulospinal tract: Descending pattern?

Ipsilateral

Lateral vestibulospinal tract: Region of synapse?

Cervical/lumbar

Lateral vestibulospinal tract: Functions?

Facilitates stimuli to LMN’s from extensors and inhibits LMN’s to flexors

Reticulospinal tract: Origin?

Pontine reticular formation (pons)

Reticulospinal tract: Descending pattern?

ipsilateral

Reticulospinal tract: region of synapse?

Cervical/lumbar

Reticulospinal tract: Functions?

Stimulates postural trunk muscles and limb extensors

Medial corticospinal: Origin?

Cerebral cortex

Medial corticospinal: Descending patterns

Ipsilateral

Medial corticospinal: region of synapse

cervical

Medial corticospinal: Functions?

Voluntary pathway that controls head movement.

What is Paresis?

Partial paralysis or weakness

Paralysis: Hemiplegia is?

loss affecting one side of the body; usually brain injury

Paralysis: Paraplegia is?

oss affects the body below the arms; usually spine below T1

Paralysis: Tetraplegia/Quadriplegia is?

loss affects all four limbs; spinal damage, cervical region

Atrophy is?

Loss of muscle bulk

Disuse atrophy:

Results from lack of muscle use

Neurogenic atrophy:

Results from damage to the LMNs, not by lack of use

Flaccid Paralysis:

Weakness or loss of muscle tone (stiffness or resistance to stretch or limp and cannot contract); caused by infections or inflammations to the cell bodies of the LMNs or immune problem

Babinski’s sign:

Extension of great toe, often accompanied by fanning of the other toes

Clonus:

Involuntary, repeating, rhythmic muscle contractions.