Motor Control Chapter 8 Flashcards
Skeletal muscle is composed of two fiber types:
Extrafusal, Intrafusal
This type of skeletal muscle is innervated by alpha-motor neurons from the spinal
cord: exert force
extrafusal
This type of skeletal muscle is innervated by gamma-motor neurons
Intrafusal:
This type of muscle fiber reports the length of intrafusal: when stretched, the fibers
stimulate the alpha-neuron that innervates the muscle fiber: maintains
muscle tone
- Afferent fibers:
This type of muscle fiber deals with contraction adjusts sensitivity of afferent fibers.
- Efferent fibers:
Each muscle fiber consists of a bundle of
myofibrils
Each myofibril is made up of overlapping strands of ____
actin and myosin
The ____ is the synapse formed
between an alpha motor neuron axon and a muscle fiber
The neuromuscular junction is the synapse formed
between an alpha motor neuron axon and a muscle fiber
Each axon forms synapses with several muscle fibers
(forming a motor unit)
____ is the neuromuscular junction neurotransmitter
ACh
Smooth muscle is controlled by the
autonomic nervous system
_____ smooth muscle is normally inactive
* Located in large arteries, around hair follicles (for piloerection) and in
the eye (lens adjustment, pupillary dilation)
* Responds to hormonal stimulation
Multiunit
____ smooth muscle exhibits rhythmic contraction
* Single-unit muscle is found in gastrointestinal tract, uterus, small
blood vessels
Single-unit
____ resemble striated muscle in appearance, but exhibit rhythmic contractions like that of single-unit smooth muscle
Cardiac muscle fibers
Spinal cord is organized into ___ and ____ aspects
dorsal, ventral
Dorsal horn receives incoming
sensory information
Ventral horn issues efferent fibers (alpha-motoneurons) that ____
innervate extrafusal fibers
______ involve a single synapse between a sensory fiber from a muscle and an alpha-motor neuron
– Sensory fiber activation quickly activates the alpha motor
neuron which contracts muscle fibers
* Patellar reflex
Monosynaptic reflexes
____ involve multiple synapses between
sensory axons, interneurons, and motor neurons
– Axons from the afferent intracellular muscle fibers can synapse
onto:
* Alpha motoneuron connected to the agonist muscle
* An inhibitory interneuron connected to the antagonist muscle
– Signals from the intracellular muscle activate the agonist and inhibit the
antagonist muscle
Polysynaptic reflexes
Primary motor cortex is located on the
precentral gyrus
Motor cortex receives input from
- Premotor cortex
- Supplemental motor area
- Primary somatosensory cortex
____ controls where to move, ____ controls what is moving, and _____ plans what to move
parietal, temporal, frontal
Planning of movements involves the _____
and the _____ which influence the primary motor cortex
premotor cortex, supplemental motor area
“ideational apraxia” – verbal domain (a neurological disorder characterized by the inability to conceptualize, plan, and execute complex sequences of motor action)
– Sequencing complex behavior of talking is controlled by what part of the brain?
Left Frontal Lobe
“Ideational apraxia” – spatial domain what part of the brain?
Right frontal Lobe
Motor Pathways
Lateral Group – controls _____
* More “lateralized”
– Ventromedial group – controls _______
* More “medial”
controls independent limb movements
gross or coordinated limb
movements
_____
* Corticospinal tract: hand/finger/foot movements
* Corticobulbar tract: movements of face, neck, tongue, eye (independent)
* Rubrospinal tract: fore- and hind-limb muscles
Lateral group:
_____
* Vestibulospinal tract: control of posture
* Tectospinal tract: coordinated eye and head/trunk movements
* Reticulospinal tract: walking, sneezing, muscle tone (coordinated)
* Ventral corticospinal tract: muscles of upper leg/trunk
Ventromedial group:
rubrospinal track crosses over by ____!
pons
corticospinal track (dark blue; upper legs and trunk) stays ____ and projects ____ ! (part of ventromedial pathways)
ipsilateral, bilaterally
Basal ganglia consists of (3)
– Input to the basal ganglia is from the
caudate nucleus, putamen and the globus pallidus,
substantia nigra
– Output of the basal ganglia goes to
- Primary motor cortex, supplemental motor area, premotor
cortex - Brainstem motor nuclei (cerebellum to descending motor
pathways)
_____ involves muscle rigidity, resting tremor, slow movements, postural
instability
Parkinson’s disease (PD)
Parkinson’s results
from damage to dopamine neurons within the nigrostriatal bundle (projects to caudate and putamen)
What area of the brain do you stimulate for deep brain stimulation for Parkinson?
Subthalamic Nucleus
Huntington’s disease (HD) is:
involves uncontrollable, jerky
movements of the limbs & terrible balance
HD is caused by ____
– HD is a hereditary disorder caused by a
* If one parent has the disorder, each child has a ___ chance of acquiring the
disorder
degeneration of the caudate nucleus and putamen
* Cell loss involves GABA-secreting axons that innervate the external
division of the globus pallidus
50%
_____ refers to an inability to properly execute a learned
skilled movement following brain damage
Apraxia
Sympathetic apraxia causes what?
damage to anterior left hemisphere causes paralysis of right arm and hand
What is Callosal apraxia
person cannot perform movement of left hand to a verbal request (anterior callosum interruption prevents information from reaching right hemisphere)
What is Left parietal apraxia
difficulty in initiating movements to verbal request
What is Constructional apraxia
caused by right parietal lobe damage, Person has difficulty with drawing pictures or assembling objects
What is flexion vs Extension
contraction of a flexor muscle draws in a limb (positive working out)
contraction of extensor muscle “Anti-gravity (negative working out)
