Chapter 11: Motor and Somatosensory Flashcards
Compare somatosensory and motor pathways as far as their direction and location in the spinal cord
Somatosensory = sensory, afferent, posterior Motor = efferent, anterior
What are the 4 main dermatomes and what part of the body do they relate to?
Cervical: arms
Thoracic: chest
Lumbar: Legs
Sacral: Bum and legs
What is a motor sequence? What are they the base for argued by Lashley?
movement modules preprogrammed by brain and produced as a unit; the base for complex movement
What 3 parts of the brain take part in initiating a motor sequence? What does each do?
Prefrontal cortex: plans our behavior and specifies a goal
Premotor cortex: organizes movement sequences; produces movement with many body parts
Primary motor cortex (M1): focal skilled movements
What part of the brain is involved in species-typical movement? What are some qualities of these behaviors?
brainstem; they are innate and depend on context as well
What does the motor cortex represent at the basic level?
fundamental movement categories
Where is the supplementary motor cortex?
in the premotor area of the frontal lobe
What is a corticospinal tract? What are the 2 and where do they branch off?
nerve fibres connecting cerebral cortex to the spinal cord; opposite-side lateral tract and same-side anterior tract; the brain stem
What does the opposite side lateral tract inform movement of?
the limbs and digits
What does the same-same anterior tract inform movement of?
the trunk
Where do motor neurons send axons to body muscles?
in the anterior horn
What are the 2 contraposing types of muscles?
extensor (away) and flexor (toward); work in opposition
What is the basal ganglia composed of?
the caudate nucleus, putamen, globus pallidus and subthalamic nucleus
What are the 3 connections involving the basal ganglia?
1) Neocortex + allocortex –> basal ganglia
2) basal ganglia –> thalamus –> motor cortex
3) substantia nigra basal ganglia
What can damage to the putamen result in?
dyskinesias (twitching) or hyperkinetic and hypokinetic symptoms
What acts as volume control in the basal ganglia, how?
globus pallidus; inhibited = movement vs excited = no movement
What does the flocculus do in the cerebellum?
receives information from the middle ear for balance control and controls eye movements
What cell type is in the 2nd layer of the cerebellum? What is it’s function?
purkinje cells; it is the output layer
What does damage to the cerebellum result in?
doesn’t abolish movement but disrupts it’s timing and execution
What is the cerebellum’s main process of integrating information?
comparing information about the intended vs actual movements and deciding what to do next
What is glabrous skin?
skin without hair follicles but with more sensory receptors
What are the 3 types of somatosensory receptors?
1) Nociceptors
2) Hapsis
3) Proprioreceptors
What are some qualities of nociceptors? What kinds of cells are they?
they are involved in irritation and the perception of pain, temperature and itch; free nerve cells
What are some qualities of hapsis receptors? What kind of cells are they?
They respond to pressure and touch and allow us to discriminate objects; a dendrite attached to hair, connective tissue or encased in connective tissue
What are some qualities of proprioceptors? What kind of cells are they?
involved in the perception of movement and body, limb and head position; encapsulated nerves sensitive to stretch
What are the 4 main types of Hapsis receptors?
1) Pacinian
2) Merkel
3) Ruffini
4) Meissner’s
What is a pacinian corpuscle responsible for? Is it rapid or slow?
flutter movements; rapid
What is a Meissner’s corpuscle responsible for? Is it rapid or slow?
touch; rapid
What is a Ruffini corpuscle responsible for? Rapid or slow?
indentation; slow
What is Merkel’s receptor for? Rapid or slow?
stead skin indentation; slow
Are proprioceptors all rapid or slow?
rapid
Are nociceptors rapid or slow?
slow
What are posterior root ganglion neurons?
Single long dendrites just outside the SC that carry somatosensory information to the CNS
What are the 2 types of posterior root ganglion neurons and how do they differ?
1) Proprio & haptic; large and myelinated
2) Nociceptive; small and nonmyelinated
What type of cells are in the posterior spinothalamic tract? Where do they cross over?
Haptic and proprio; in the posterior column nuclei in the brain
What type of cells are in the anterior spinothalamic tract? Where do they synapse and cross over?
nociceptors; on anterior grey matter; cross over right away
Where do both spinothalamic tracts end up synapsing on in the brain?
the ventrolateral thalamus
What areas other than nociceptors are involved in pain perception? What do they do?
Haptic: ID location and identity
Midbrain: arousal
Amygdala: emotional response
Hypothalamus: hormonal and cardio vascular
What is the gate theory of pain?
haptic-proprio can reduce pain perception whereas absence can increase pain perception
How is the PAG involved in pain perception? What can be done with it to reduce pain?
in the midbrain and is related to opioids; stimulating it reduces pain perception
What is another name for organ pain? why?
referred pain; because you feel it elsewhere
What is involved in the vestibular system? What is a disease that can result in vertigo in this system?
the semicircular canals detect 3d location and ID; cilia fire to one direction and inhibited to other; Miniere disease
Where does the primiary somatosensory cortex receive projects from? What Brodmann’s areas is it? What are it’s main functions?
the thalamus; 3-1-2; construct perceptions from somatosensory information
What Brodmann’s areas is S2? What does it do? Where is it?
5 and 7; in parietal behind S1; refines perceptual construtions and sends info to frontal cortex
What are the 4 different somatosensory homunculi?
1) rapid adapting skin receptors
2) deep tissue pressure and joint receptors
3a) muscle receptors
3b) slow respond skin receptors
What do somatosensory homunculi areas of 3a and 3b do?
respond to specific activity of certain body parts; integrate it and send it to area 1
What is apraxia? What is damaged a lot of the time that it results?
inability to make voluntary movements; especially to make proper use of an object; S2
What is astereognosia?
inability to recognize objects by touch
What is asomotagnosia?
inability to recognize body parts
What two more parts are involved in pain perception?
the anterior cingulate cortex; emotional
Raphe nucleus; can monitor and block pain
What is unique about ballistic movements?
they require no sensory feedback
What does the posterior parietal association cortex do?
it integrates information on body position, external objects; it receives information from all senses
What does the dorsolateral prefrontal association cortex do?
it evaluates external stimuli and initiates reactions to them; it is the first to fire in anticipation of motor responses
Where does stimulation of the primary motors cortex produce movement?
the opposite side of the body
What do the 2 dorsolateral and ventromedial tracts have in common? How do they differ?
Both: project from M1 and mediate voluntary movement
Ventro: more diffuse and send information to proximal muscles
Dorso: project to distal muscles
What is isomeric muscle contraction?
joint position and muscle length do not change; do not pull bones in
What is Dynamic muscle contraction?
muscle length and joint position change; bones are pulled in
What reflex is monosynaptic? What isnt?
stretch reflex (petallar) withdrawal (nociceptors)
