Exam 1 Flashcards
alpha motor neuron
- project to extrafusal skeletal muscle
- ALWAYS LMN - from synapse to muscle
- have large cell bodies & large myelinated axons
- release enough ACh that all muscle fibers it innervates contract
gamma motor neuron
- project to intrafusal fibers of muscle spindle
- have medium-sized myelinated axons
muscle spindle
type 1a
GTO
type 1b
presynaptic inhibition
STOPPING A REFLEX: Conscious thought – volition – CNS from brain – Corticospinal tract – presynaptic inhibition to stretch reflex arc by causing hyperpolarization & releases NT GABA (inhibitor) = UMN
Voluntary movement
- Corticospinal tract - UMN
- Initiated in response to something in the environment
- Purposeful, meaningful, and goal directed
- Learned automatic movements like writing or keyboarding
Reflex movement
Rapid and involuntary
Central pattern generation
- Interconnection of neurons that produce rhythmic movements like walking and chewing
- These movements are typical to the individual but may vary across subjects
Coordinated movement
-Coordinated movement requires agonist and antagonist movements for both static and dynamic adjustments
-Examples: sitting posture and reaching
-Sensory Information:
Exteroceptors are the representation of the spatial coordinates or self, objects, and the environment
-In order to coordinate movement a variety of proprioceptive and spatial information is needed depending on the activity being performed
Refine movement
Basal ganglia & cerebellum
afferent to efferent process
Afferent –> thalamus –> parietal (primary somatosensory) –> cortex –> corticospinal (UMN) –> refined by basal ganglia & cerebelum –> spinal cord –> muscle
Feedback
- closed loop model (input, error, instructions, output, feedback)
- Correct via feedback from proprioception, touch, etc. to tighten grip in slippery water bottle
Feedforward
- Open control (input, instructions, output)
- Input from gustatory receptors says I’m thirsty & brain decides to pick up glass
- Feedforward is faster – not relying on any feedback info
Control of Movement
- Top-down (brain to spinal cord to muscle)
- Motor neurons: control skeletal muscles
- LMN: innervate skeletal muscles
- UMN: descending tract
- Control circuits: Basal ganglia and Cerebellum
Upper Motor Neurons
Descending tracts:
- Postural/gross movement tracts
- Fine movement & limb flexion tracts
- Non-specific UMN
ATP
A common form in which energy is stored in living systems; consists of a nucleotide (with ribose sugar) with three phosphate groups. The energy coin of the cell
SMA
- Supplementary Motor Area LOCATION: - Medial portion of Broadman’s area 6 FUNCTION: - Initiation of movement, orientation of eyes & head, planning bimanual & U/L sequential movements CONNECTION: - Thalamic input from ventral anterior nucleus - Send to the primary motor area - Basal Ganglia - Brainstem - Spinal Cord
PMA
- Pre-Motor Area LOCATION: - Broadman's area - Anterior to the primary motor cortex FUNCTION: - Controls trunk & girdle muscles via medial UMN CONNECTION: - Thalamus - Basal ganglia - Brainstem - Spinal cord
M1
– Area 4 or primary motor cortex
LOCATION:
- Precentral gyrus Broadman’s area 4
FUNCTION:
- Responsible for the execution of skilled movements
- Generates individual muscle movements as well as movements that cross joint
- Responsible for directing the amount of force needed by a muscle or for a movement
CONNECTIONS:
- Receives information form the thalamus ventral lateral nucleus
- Sends to ‘higher order motor areas
-Premotor cortex
-Basal ganglia
-Cerebellum
ORGANIZATION:
- Somatotopical organization of the entire body
- Represents 30% of the corticospinal tract
S1
– Primary Sensory Cortex
Dorsolateral Prefrontal Cortex
– front side portion of prefrontal cortex
- executive functioning
Cingulate Motor Area
LOCATION: - Cingulate gyrus - Medial portion of the cerebral cortex - Broadman’s area 24 and 6 FUNCTION: - Mediates emotional movements - Considered part of the limbic system CONNECTIONS: - Receives from the amygdala - Communicates though the basal ganglia to mediate motor movements
Lesions to M1
- Hemiplegia
- Contralateral weakness
- Impaired postural righting and equilibrium reactions
Lesions to PM
Uncoordinated clumsy movement
Lesions to SMA
- Inability to initiate movement
- Overall lack of movement referred to as akinesia
- Apraxia or difficulty with motor planning
Medial UMNs
- medial white columns; postural + girdle
- 4 tracts:
Tectospinal
Medial Reticulospinal
Medial & Lateral Vestibulospinal
Medial Corticospinal - All tracts are more Automatic
Lateral UMNs
- lateral white columns; distal/fine movt.
- 3 tracts:
Lateral Corticopinal
Rubrospinal
Lateral reticulopsinal - Limb flexion
- Fine movements of the limbs
Non-specific UMNs
- throughout ventral columns;
background excitation + local reflex arcs - 2 tracts
Ceruleospinal
Raphespinal - Enhance activity of interneurons and motor neurons in spinal cord
- Emotional motor system
Medial corticospinal
- straight down from motor cortex – runs near midline
- (15% of the pyramidal tract):
- Voluntary movement, primarily of the neck, shoulder & trunk muscles
Lateral vestibulospinal
vestibular nucleus in medulla down to spin – regulates more automatic mvmt
- Vestibulospinal - Positioning and movement of the body and head, muscle tone, maintain center of gravity over base of support
Tectospinal
– tectum of midbrain (4 colliculi = bumps) – superior colliculi, crosses in midbrain, down to spine
- Reflexive response to visual and auditory stimuli
Medial reticulospinal
– reticular activating system of pons to spine
- General positioning (trunk/postural muscles + extensors) and muscle tone
Medial vestibulospinal
– vestibular nucleu, crosses in medulla, down to spine
- Vestibulospinal - Positioning and movement of the body and head, muscle tone, maintain center of gravity over base of support
Lateral Corticospinal
- (85% of the pyramidal tract):
- Voluntary movement, primarily of the extremities,
- Fractionation/individuation of movement (individual finger movement, in hand manipulation)
Rubrospinal
Voluntary movement of trunk and limbs
